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Opravil, Tomáš. "Příprava a vlastnosti románského cementu." Doctoral thesis, Vysoké učení technické v Brně. Fakulta chemická, 2009. http://www.nusl.cz/ntk/nusl-233293.
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The Ph.D. thesis deals with the preparation of highly hydraulic binders based on roman cement. Roman cement (natural cement) is recently not available on the market due to uneconomic production of such a specific binder. On the other hand there is a big lack of information on this hydraulic binder. These results in failure in meeting the basic principle of modern approaches to restoration of historical buildings or monuments made of such kind of materials, which is such, that the materials used for restoration should be compatible with original material. Recognition of the processes of roman cement preparation based on progressive methods of study can provide substantial information for more efficient raw material selection or even for nontraditional utilization, for example for artworks. This work hence is aimed at studying and selection of traditional natural as well as nontraditional raw materials such as clay. This work also studies the preparation of highly hydraulic binders based on roman cement and the kinetics of burning and hydration processes
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Tranová, Kateřina. "Hydraulická analýza vodovodní sítě městské části Brno - Ivanovice." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2017. http://www.nusl.cz/ntk/nusl-265396.
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This diploma´s thesis aims to model the hydraulic model of the Brno – Ivanovice water supply system. The software MIKE URBAN for model hydraulic model of water supply system was used. It was performed a simulation of the various states of loading. The water supply system was assessment of pressure ratios. The outcome of this work is calibrated hydraulic model of water supply system. The appendix consists also of drawings, which represented pressure ratios, which are situated on water supply system. On the fourth drawing is described transparent situation of Brno-Ivanovice water supply system.
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Forsberg, Johan. "Model-based study of the energy efficiency of two different types of harvester cranes." Thesis, KTH, Maskinkonstruktion (Inst.), 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-156712.
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In today’s forest industry two mechanized methods are used, the Tree Length (TL) method and the Cut To Length (CTL) method. With the Tree Length method, trees are harvested and extracted from the forest as a whole tree to be further processed whereas with the Cut To Length method trees are harvested, branches are removed and the tree is cut to desired length to be extracted by a forwarder. The Cut To Length method is now a day 100 percent mechanized and more and more emphasis is put on efficiency in both harvesting and forwarding the trees. Efficiency can be measured in trees harvested per hour but also in fuel consumption. As an effect, the performance of the machines is in higher demand. Ponsse Plc is a finnish forestry machine company with production in Vieremä where both harvesters and forwarders are manufactured. Cranes and loaders are also made by Ponsse to match their harvesters and forwarders. Ponsse manufactures two designs of harvester cranes; a sliding boom crane and a parallel crane. The different types of cranes have the same reach but with different geometries and weights, which also leads to different momentum of inertia. The purpose of this master thesis is to investigate, from an energy efficiency point of view, the difference in performance between a sliding boom crane, C2, and a parallel crane, C22 by measuring the hydraulic pump’s flow and the rotational energy of the cranes. This has been done by modelling the cranes’ hydraulic circuits and by using 3D-CAD models with mass and inertias in Simulink. More specific, only the crane tips of the cranes have moved along a set trajectory, equal for both crane types. Different range and loads have been simulated. The energy needed for rotating the cranes have been calculated for different crane tip positions and compared. Simulink simulations gave beneficial results for the parallel crane when unloaded and acting at a shorter reach. For longer reach, the sliding boom crane was more efficient. The calculations of the cranes rotational energies showed that the parallel crane C22 yielded higher values than the C2 at shorter distance from the axis of revolution. The C2 crane had however slightly higher values than the C22 crane at longer reach, but it should be noted that differences were small. From this analysis, it is concluded that the C2 crane has an overall lower need of rotational energy and is therefore deemed the better crane. Keywords: Forest machines, hydraulics, efficiencyI världen idag existerar två mekaniserade skördartekniker inom skogsavverkningen, helträdsavverkning och kortvirkesavverkningen. Den första innebär att hela träd skördas och skotas ut till en uppläggningsplats medan man inom korttimmeravverkningen istället fäller träden med en skördare som sedan kvistar och till sist kapar trädet till önskad längd. Denna avverkning är numera 100 procent mekaniserad och effektivare avverkning är ständigt i blickfånget. Effektivare avverkning kan yttra sig i antalet fällda träd per timme men också i bränslekostnader. Dessa krav ställer i slutändan krav på skördarna och skotarnas prestanda. Ponsse Oyj är ett finskt skogsmaskinsföretag med fabrik i Vieremä som tillverkar både skördare och skotare. Till dessa maskiner tillverkar man även egna kranar. För skördare har man två olika designer, dels en bomkran och dels en parallellkran. Dessa båda krantyper har lika räckvidd men olika geometrier och vikt, vilket också innebär att masströgheterna skiljer dem åt. Syftet med detta examensarbete har varit att undersöka en av vardera krantypen, C2 från bomkrantypen och C22 från parallelltypen ur ett energieffektivitetshänseende. Detta har gjorts genom att mäta hydraulpumpflödet och kranarnas rotationsenergi. Mer specifikt har båda kranarna modellerats i Simulink med hydraulik och mekanik för att avgöra vilken av kranarna som är effektivast när kranspetsen har flyttats i en rörelse lika för båda kranarna. Kranspetsrörelsen simulerades med olika laster och för olika rörelser. Denna rörelse har varit i planet och för att jämföra kranarna vid vridning har kranspetsen placerats i olika positioner och masströgheten beräknats för vridning kring rotationsaxeln. För given rotationshastighet beräknades sedan vederbörande rotationsenergi för de olika positionerna. Simuleringarna resulterade i en fördel för parallellkranen vid korta sträckor och obelastad kran. För längre räckvid visade istället bomkranen bättre effektvärden. För rotation av kranarna kring dess rotationsaxel med kranspetsen i olika positioner visar parallellkranen C22 högre energivärden än bomkranen när kranspetsen är placerad fem meter från rotationsaxeln men för positioner längre ut, vid 9,9 respektive 10 meter påvisar C2 kranen kräva högre energi, om än i nivå med parallellkranen. Energieffektivast ur rotationshänseende är således bomkranen då den överlag behöver lägre energi eller i nivå med den andra. Nyckelord: Skogsmaskiner, hydraulik, effektivitet
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Kolenčíková, Jana. "Model teplárenské sítě." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2020. http://www.nusl.cz/ntk/nusl-417740.
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Subject of this thesis is district heating and heating network model design. Firstly, it de-scribes basic principles of heat supply and its elements. Secondly, computational model of heating network is created based on grid map of the network. The model contains proposed pipeline system and calculation of heat and pressure losses. Lastly, price map for heat con-sumption points, in dependence on heat losses, is presented.
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Holma, Evert. "Designkoncept för standard hydraulik modul." Thesis, Umeå universitet, Institutionen för tillämpad fysik och elektronik, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-125093.
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Detta examensarbete har genomförts på Outotec i Skellefteå, det är ett finskt företag som levererar process- och automationslösningar för metall-, mineral-, energi- och vattenindustrin. Hydraulik ingår i många av Outotecs maskiner och processlösningar och där har ett önskemål funnits om att ha en mindre hydraulmodul för att driva enklare funktioner som använder sig av cylindrar. Detta examensarbete har gått ut på att ta fram ett designkoncept för en mindre hydraulmodul för att driva cylindrar som används för att köra enklare funktioner i en smältverksanläggning. Arbetet omfattar ett framtagande av ett hydraulschema för modulen där nödvändiga komponenter skall ingå, ett beräkningsunderlag för att kunna välja komponenter till modulen. Samt ett förslag på vilka större och viktiga komponenter som kan användas för systemet och ett designförslag på hur modulen kan komma att se ut vid ett färdigställande. Som ett resultat av detta har ett beslutsunderlag tagits fram för att kunna färdigställa modulen, beslutsunderlaget baseras på beräkningar som är gjorda på de olika cylindrarna samt komponenter som kommer att behövas i modulen. Ett antal av komponenterna är valda och kan ses som en riktlinje för ett slutgiltigt beslut, så det är möjligt att välja en liknande produkt av ett annat fabrikat eller andra dimensioner. Resultatet innehåller även ett hydraulschema som beskriver funktionen för modulen och vilka komponenter som bör ingå då modulen är färdig. Ett förslag på konstruktion och layout är framtaget för modulen, denna innehåller dock inte alla komponenter men de största komponenterna finns med som tank, motor och ackumulator.This thesis has been conducted at Outotec in Skellefteå, Outotec is a Finnish company that supplies process and automation solutions for metal, mineral, energy and water industries. Hydraulics are included in many of Outotec's equipment’s and process solutions and because of this they have come to the idea of having a smaller hydraulic module for operating simple functions that use hydraulic cylinders. This thesis has been to develop a design concept for this small hydraulic module to operate the cylinders that are used to run simple functions in a metal melting plant. The work includes the development of a hydraulic diagram for the module where the necessary components are included, the calculation basis for selecting components to the module, a proposal on which significant and important components that can be used for the system and a design proposal on how the module might look at a completion. As a result of this, a decision basis was developed in order to complete the module. The decision data are based on calculations made on the components that will be needed in the module and the various functions that the module is supposed to run. The bigger components are selected and can be seen as a guideline for a final decision, so it is possible to choose a similar product but with other dimensions or products from another manufacturer. The result also includes a hydraulic diagram describing the function of the module and which components that should be included when the module is completed. A draft of the design and layout is designed for the module, this does not contain all the components, but the main components are included such as the tank, motor and accumulator.
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Pospíšil, Radek. "Tlumení energie proudu vodním skokem v prostoru rozšíření koryta." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2020. http://www.nusl.cz/ntk/nusl-409720.
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The diploma thesis is focused on the evaluation of the suppression of supercritical current energy in the area of the river bed extension. The hydraulic model was used to simulate current conditions for different variants of river bed arrangement. Individual variants were then evaluated according to the relevant criteria and compared with each other. Results can be applied in hydrotechnical practice based on model similarity.
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Pařízková, Iva. "Matematický model teplárenské sítě." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2016. http://www.nusl.cz/ntk/nusl-241664.
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This thesis is focused on creating an iterative model for thermal and hydraulic calculation of heating net in Visual Basic of Application. Flowing medium considered is hot water. Although data for heating network in Brno are recorded in this model, its use for any other heating network is possible. This model allows also calculation of minimal temperature of the source and calculation of heat loss of every consumer. This is very useful when considering, if supplying some of the consumers with the heat from a local source would not be more effective. The second part of this text is aimed to evaluation of different ways how to reduce the heat loss in heat network for source Červený mlýn. Both current situation and possibilities for the future are considered.
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Mrázek, Jan. "Posouzení vybrané části vodovodní sítě." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2021. http://www.nusl.cz/ntk/nusl-433394.
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The aim of this thesis is to research the field of water distribution system monitoring and modeling such system. In the next section the thesis describes a part of the water distribution system which is located in Pardubice district, specifically south of town Přelouč. With knowledge from the done research a hydraulic model will be done. This model made in EPANET interface will be calibrated and verified using data, which was acquired by the administrator of the system VAK Pardubice a.s. Afterwards new pipelines will be added to simulate the future situation accordingly to the area plans of the cencerned towns. Furthermore another aim is to simulate the requirements made towards the water distribution system in the future in case all the areas in area plan will be completely used. This will result into creation of forward looking hydraulic model which will show possible weaknesses of the water distribution system. In case of any shortcomings, according measures will be designed for future use.
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Howe, Edmund. "Hydraulic Assessment of Notched River Training Structures on a Portion of the Lower Mississippi River Using the Adaptive Hydraulics Model." Thesis, Mississippi State University, 2017. http://pqdtopen.proquest.com/#viewpdf?dispub=10275634.
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River training structures are widely used to create and maintain navigable waterways, to restore rivers and channels in a more stable condition, to promote environmental benefits, and to protect people and infrastructure from damages or floods. Few historical datasets on the changes and impacts in secondary waterbodies resulting from notched river training structures are available for the Lower Mississippi River. Access to the notched training structures on the Lower Mississippi River remains difficult and inhibits data collection for monitoring efforts. This increases the need for alternative methods such as numerical models for assessing the performance of the notched training structures. A quasi-three-dimensional Adaptive Hydraulics model was assembled and used to provide a hydraulic assessment of seven notched river training structures in the Lower Mississippi River. The hydraulic assessment of the notches included assessing the impacts to navigation, the long-term trends, and the potential for aquatic wildlife habitat diversity.
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Hradilová, Iva. "Modelování hydraulické účinnosti vícekomorových septiků." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2015. http://www.nusl.cz/ntk/nusl-227222.
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The submitted diploma thesis is focused on finding optimal inside arrangement of multi-chamber septic tank using the conductive method. The diploma thesis brings detailed description and measuring results, including the testing of several different arrangements of the standard circular three chamber septic tank in the project TAČR with the working title "Anasep" and newly developed four-chamber septic tank with several innovative features. The results are then categorized according to own terminology for ease application in the practice. The described method may be a suitable alternative for other technically and economically less available methods. The method shows very clearly whether the inner space of the septic tank sufficient use its volume to the velocity field distribution which has a direct impact on the rate of sedimentation of suspended solids and therefore affect the life of the downstream filtration equipment. Measured data processing and graphical outputs were processed in the programme Minitab. Graphical display of all variants of septic tanks was carried out using SketchUp. Visualization of a septic tank in 2D and 3D space plane was solved in COMSOL Multiphysic with the application of CFD module. The conclusion is based on achievements discussed the applicability of the described method and it presented hydraulically efficient multi-chamber septic tank, which is currently copyrighted solution, developed by a team of solvers in the project ANASEP.
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Balas, Jan. "Hydraulické posouzení stokové sítě obce Lipůvka." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2017. http://www.nusl.cz/ntk/nusl-265284.
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Diploma thesis is focused on hydraulic assessment of Lipůvka´s sewer system, done by dynamic rainfall-runoff simulation model. Because of this fact, chapter about mathematical models is included. Commonly used programs to this actions are listed as well. Next part of the thesis describes monitoring campaign, which was done in Lipůvka and results are used to calibrate the simulation model. Hydraulic assessment of sewer system by this calibrated model was done.
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Petrula, Lubomír. "Hodnocení kontaminace podzemních vod v oblasti Letiště Přerov." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2017. http://www.nusl.cz/ntk/nusl-265335.
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The main goal of this work is to assess ground water contamination at the Přerov airport as a consequence to oil products leakage. For this purpose a flow and transport model was created. Another goal is to create and assess several variations of unfavorable scenarios in terms of water quality. The final goal is to create a set of recommendations for the entire area.
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Voldán, Karel. "Studie sanace stokové sítě vybrané části urbanizovaného celku." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2018. http://www.nusl.cz/ntk/nusl-372014.
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The aim of the diploma thesis was the elaboration of a study of the rehabilitation of the sewerage network in the part of the town of Znojmo. The work is conceived in the form of accompanying and technical reports. The accompanying report contains a brief description of the interest site, basic information about the sewerage system operator and land data. The technical report contains a description of the individual segments of the sewer network, supplemented by photo documentation of the selected faults located on the selected sections. In addition, the evaluation of the structural state of the sub-sections is carried out here. The following subchapter draws up two hydraulic models and their modifications after the recovery of the sewer system. Another part of the technical report describes possible options for remediation technologies. The last part deals with the conclusions and recommendations for the sewer network operator including a briefly outlined economic page in the selection of remediation technology.
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Yang, Bo. "Elastohydrodynamic model of reciprocating hydraulic rod seals." Diss., Georgia Institute of Technology, 2010. http://hdl.handle.net/1853/34747.
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Reciprocating rod seals are widely used in hydraulic systems to prevent the hydraulic fluid from leaking into and polluting the environment. In this research an elastohydrodynamic model of a generalized reciprocating hydraulic rod seal, including mixed lubrication and surface roughness, has been successfully developed. This model consists of coupled fluid mechanics, contact mechanics, thermal analysis and deformation analyses.
Such model is capable of predicting the key seal performance characteristics, especially net leakage and friction force. This allows evaluation of potential seal designs and serves as design tools. Also as this model has been developed, the basic physics of seal operation has been clarified, which stimulates the development of innovative seal concepts, such as seals with engineered sealing surfaces.
The results of this study indicate that in general, hydraulic rod seals operate in the mixed lubrication regime, although under certain conditions full film lubrication may occur over a portion of the sealing zone. The roughness of the seal surface and the rod speeds play important roles in determining whether or not a seal will leak. Cavitation during the outstroke and partial full film lubrication during the instroke tend to prevent net leakage. The behavior of a reciprocating hydraulic rod seal with a double lip or two seals in tandem arrangement can be very different from that of a similar seal with a single lip. For the double lip seal, the secondary lip can strongly affect the behavior of the primary lip by producing an elevated pressure in the interlip region. The same seal characteristics that promote effective sealing in a single lip seal and, in addition structural decoupling of multiple lips, are found to promote effective sealing in a multiple lip seal.
The model is validated through comparisons of model predictions with experimental measurements and observations by industry partners. The results have shown the predicted leakage and friction force for various seal and operation conditions are consistent with the measurements.
A seal with micro-pattern on the sealing surface also has been investigated. The results indicate that an elaborately designed pattern can improve the sealing characteristics of the seal, without significantly affecting the friction force.
In the end, the selection of the rod seal for a specific application using this analytical model is demonstrated. The best design can be picked up before a prototype being built.
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Van, Der Merwe Carel Wagener. "A peridynamic model for sleeved hydraulic fracture." Thesis, Stellenbosch : Stellenbosch University, 2014. http://hdl.handle.net/10019.1/95993.
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Thesis (MEng)--Stellenbosch University, 2014.ENGLISH ABSTRACT: Current numerical methods in the eld of hydraulic fracturing are based mainly on continuum methods, such as the Finite Element Method (FEM) and the Boundary Element Method (BEM). These methods are governed by Linear Elastic Fracture Mechanics (LEFM) criteria, which su er from the inherent aw of a non-physical stress representation at the fracture tip. In response to this, a non-local method is proposed, namely the peridynamic theory, to model sleeved hydraulic fracture. A 2D implicit quasi-static ordinary state based peridynamic formulation is implemented on various benchmark problems, to verify the ability to capture constitutive behaviour in a linear elastic solid, as well as, the quanti cation of adverse e ects on the accuracy of the displacement solution, due to the nature of the non-local theory. Benchmark tests consist of a plate in tension, where convergence to the classical displacement solution, non-uniform re nement and varying cell sizes are tested, as well as, a thick walled cylinder with internal pressure, where three di erent loading techniques are tested. The most accurate loading technique is applied to the sleeved fracture model, in order to simulate fracture initiation and propagation. This model is then veri ed and validated by using the Rummel & Winter hydraulic fracturing model and experimental results, respectively. Displacement error minimisation methods are implemented and as a result, the displacement solutions for a plate in tension converges to the analytical solution, while the thick walled cylinder solutions su er from inaccuracies due to an applied load on an irregularly discretized region. The fracture initiation test captures the fracture tip behaviour of the Rummel & Winter model and the fracture propagation test show good correlation with experimental results. This research shows that the peridynamic approach to sleeved hydraulic fracture can yield a realistic representation of fracture initiation and propagation, however, further research is needed in the area of a pressure load application on a solid using the peridynamic approach.
AFRIKAANSE OPSOMMING: Huidige numeriese metodes in die veld van hidrouliese breking is hoofsaaklik gebaseer op kontinuum metodes, soos die Eindige Element Metode (EEM) en die Rand Element Metode (REM). Hierdie metodes word beheer deur Linie^ere Elastiese Breukmeganika (LEB) kriteria, wat ly aan die inherente gebrek van 'n nie- siese voorstelling van die spanning by die fraktuur punt. Om hierdie probleme aan te spreek, word 'n nie-lokale metode voorgestel, naamlik die peridinamiese teorie, om gehulsde hidrouliese breking te modelleer. 'n 2D implisiete kwasi-statiese ordin^ere toestand gebaseerde peridinamika formulering word ge mplimenteer op verskeie norm probleme, om te veri eer of dit oor die vermo e beskik om die konstitutiewe gedrag van 'n linie^ere elastiese soliede materiaal te modeleer, asook die kwanti sering van nadelige e ekte op die verplasings oplossing as gevolg van die natuur van die nie-lokale teorie. Normtoetse bestaan uit 'n plaat in trek spanning, waar konvergensie na die klassieke verplasings oplossing, nie-uniforme verfyning en vari^eerende sel groottes getoets word, asook 'n dikwandige silinder onder interne druk, waar drie verskillende belasting aanwendingstegnieke getoets word. Die mees akkurate belasting aanwendingstegniek word dan gebruik in die gehulsde hidrouliese breking model, om fraktuur aanvangs en uitbreiding na te boots. Die model word dan geveri- eer deur die Rummel & Winter hidrouliese breking model en eksperimentele resultate, onderskeidelik. Fout minimering metodes word toegepas en as 'n resultaat, konvergeer die verplasing oplossing vir die plaat na die analitiese oplossing, terwyl die oplossing van die dikwandige silinder onakuraathede toon as gevolg van 'n toegepaste belasting op 'n onre elmatig gediskretiseerde gebied. Die modellering van die fraktuur inisi ering by die fraktuur punt, stem goed ooreen met die Rummel en Winter voorspelling en die fraktuur uitbreiding stem goed ooreen met eksperimentele resultate. Hierdie navorsing toon dat die peridinamiese benadering tot gehulsde hidrouliese breking wel die fraktuur inisi ering en uitbreiding realisties kan modelleer, maar nog navorsing word wel benodig in die area waar 'n druk belasting op 'n peridinamiese soliede model toegepas word.
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Wahler, Matthias, and Thomas Sendelbach. "Model based engineering for electro-hydraulic solutions." Technische Universität Dresden, 2020. https://tud.qucosa.de/id/qucosa%3A71232.
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This paper will give an overview about the technological change in Industrial Hydraulics and the impact of the Digital Twin on the related new engineering processes and methods in order to overcome the challenges coming out of that technology change. Simulation models will more and more become a decisive factor for the engineering process. The Digital Twin will be a window of opportunity for innovations and a technology push for the engineering process and the products in the Industrial Hydraulics.
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Wood, Melissa. "Improving hydraulic model parameterization using SAR data." Thesis, University of Bristol, 2016. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.715776.
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Albright, Lydia T. "Hydraulic Modeling of Floods in an Open Conduit Cave." Ohio University / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1596647829960682.
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Lin, Lixiang. "Hydraulic Properties of the Table Mountain Group (TMG) Aquifers." Thesis, University of Western Cape, 2008. http://etd.uwc.ac.za/index.php?module=etd&action=viewtitle&id=gen8Srv25Nme4_5115_1262826953.
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Research findings in current study provide a new insight into the fractured rock aquifers in the TMG area. Some of the results will have wide implications on the groundwater management and forms a solid basis the further study of the TMG aquifers.
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Hampson, S. P. "Nonlinear model predictive control of a hydraulic actuator." Thesis, University of Canterbury. Mechanical Engineering, 1995. http://hdl.handle.net/10092/6032.
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The main objective of this thesis is the development and implementation of a nonlinear optimal controller for a hydraulic positioning system. The controller is able to respond rapidly as well as take care of the changing dynamics within the hydraulic system.
The necessary attributes for a hydraulic actuator controller are determined by analysing the problems generally associated with hydraulic drives and reviewing the control methods that have been applied in the past. It is concluded that while significant advancements have been made in disturbance rejection, little effort has been placed on the optimal, or minimum time specifications which are frequently demanded by positioning systems. It is also noted that high perfoffi1ance hydraulic drives are prone to cavitation and a controller must necessarily avoid this.
The design of a hydraulic test rig is discussed and a novel valve drive circuit that allows direct digital control is presented. The ability of the rig to demonstrate typical control problems is established by experimental testing. The purpose of the test rig is to aid in the modelling process and for controller testing.
Power Bond Graphs are used to model the experimental rig and a comparison between a nonlinear model and experimental data shows good correlation. A linear model is also considered and shown to be ineffective at representing the rig dynamics over a range of inputs. By formulating an idealised model, valuable insights into the dynamic characteristics are obtained and the directional dependent gain of single ended rams explained.
The performance capabilities of the hydraulic rig are benchmarked by calculating the minimum time response of the hydraulic system subject to constraints on the actuator pressures, load velocity and position. A number of test cases are examined.
The research objectives of high performance and flexible constraint handling make model predictive control (MPC) an ideal approach. Model predictive controllers have been successfully applied within the chemical process industry but their application to robotics is hindered by the excessive computational requirements of the algorithm. Furthermore they are typically linear and so in their present form unsuitable. By simplifying the optimisation procedure involved in the MPC algorithm an implementable, nonlinear version of the controller has been tested. The controller is able to constrain the values of pressure, velocity and position within prescribed boundaries, thus eliminating the need for extra hydraulic components. Moreover, the speed of response is comparable to the theoretical optimum.
The work reported in this thesis contributes to the field of hydraulic systems control as it presents a novel, nonlinear optimal controller for a hydraulic positioning system. The controller differs from others reported in the literature in that it allows for the plant nonlinearities and forces the system to operate within prescribed boundaries on the state variables. As will be shown this eliminates the need for extra hydraulic components.
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Chen, Jinduan. "Stochastic Demand-hydraulic Model of Water Distribution Systems." University of Cincinnati / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1439301579.
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Tahir, Taha. "Model investigation into the hydraulic performance of mattress protected slopes of low head hydraulic structures." Thesis, University of Southampton, 1993. https://eprints.soton.ac.uk/414081/.
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The aim of this study was to provide some information about the hydraulic performance of mattresses protecting slopes of low head hydraulic structures. The flow resistance as well as stability of slope were investigated. The experimental programme was conducted in the Chilworth Hydraulics Laboratory, Department of Civil Engineering. Two models were constructed and tested. The inpermeable model (first) had a slope of 1:7 (V;H) with mattress dimensions of 320x350mm and a height of 40mm. The permeable model (second) was built with the same slope except that the mattresses were protecting a sand core. The flow resistance of the mattresses was studied which included Manning's roughness coefficient, Chezy's resistance factor and Darcy-Weisbach friction factor. Velocity distribution above the mattresses was evaluated and found well describing the flow. The stability of the mattresses and their ability to resist failure when exposed to higher discharges were also examined and found stable under the discharges tried. Detailed measurement of pressures were conducted in the permeable model in order to study their effects on the stability of the mattresses; such as; pressure distribution above the mattresses, uplift pressures and seepage forces. Shear stresses due to seepage forces were found very small and could be neglected. Comparison with the results of smooth board simulating a reinforced concrete structure, favours the mattresses as a means to control erosion and dissipate energy efficiently. Measures were suggested in terms of installation to reduce the drag and uplift forces. A design procedure for a slope protected by mattresses was set up and followed by a numerical example implementing the results obtained in this study.
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Kacálková, Eva. "Numerické modelování hydraulických ztrát v potrubí ve 3D." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2016. http://www.nusl.cz/ntk/nusl-240044.
Full textAbstract:
The bachelor´s thesis deals with numerical modelling of energy losses in pipes in 3D. It shows the process of creation of mathematical model, used mathematical equations and numerical methods of their solution. The theory is applied on the creation of pipe model and their energy losses with using different turbulent models.
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October, Adolf Gerswin. "Development of a conceptual model for ash dump system using hydraulic and tracer test techniques." Thesis, University of the Western Cape, 2011. http://etd.uwc.ac.za/index.php?module=etd&action=viewtitle&id=gen8Srv25Nme4_1072_1367481543.
Full textAbstract:
Coal provides for 77% of South Africa&rsquo
s primary energy needs and is therefore a major resource that supports the socio-economic needs of South African citizens. Power stations are the major consumers of coal in South Africa and produces electricity from burned coal. The burning of coal produces a large volume of ash that is disposed in the form of ash dump systems. The ash
dump system is treated with high salinity process water from the power station for dust suppression. The process water contains salts due to evaporation processes from the recirculation
of
water in the cooling water system. Various studies to evaluate the sustainability of the ash dump system as a sustainable salt sink were therefore conducted. This study aimed to develop a conceptual model for the ash dump system by evaluating the movement of the process water trough the ash dump and the impacts it might have on the underlying weathered dolerite aquifer. This was achieved by evaluating the hydraulic and transport properties of the ash dump system. An initial site conceptual model was first established prior to the application of the hydraulic
and transport methods. The initial conceptual model was based on the literature, previous reports and an initial site walk over. Known and tested hydraulic and transport methods were applied
n bo.th field and laboratory scale for the saturated part of the ash dump system. The laboratory experiments comprised of column and core experiments. These methods assisted in
parameter estimation of hydraulic and transport properties and also assisted in the planning of the field experiments. The field experiments were conducted in the form of slug tests, tracer
dilution and natural gradient divergent tracer test experiments. The combined laboratory and field experiments provided statistically significant values that were then used as inputs into the
conceptual model. Field experiments were also applied to a surrogate aquifer that represented the underlying shallow weathered dolerite aquifer of the ash dump system. The components of
the updated conceptual model identified and investigated include the physical environment, the calculated hydraulic and transport properties.The ash dump can be conceptualized as a 20 to
30 meter high heap of consolidated clay size ash
particles built on top of an underlying shallow weathered dolerite aquifer. The ash dup is directly connected to the underlying weathered
dolerite aquifer. The saline water within the saturated zone has the ability to move through the ash dump system with hydraulic conductivities ranging between 10-1-10- 2 m/day, with flow
velocities of 7-8m/day and effective porosities of 1%-2%. The hydraulic properties of the ash dump are, amongst others, controlled by the ash geology, contact time of the process water with the
sh and show a significant reduction in hydraulic conductivity over time, before reaching a steady state. The transport properties are controlled by advection and spreading in available
pathways. Results for the surrogate underlying fractured rock aquifer show flow velocities of 31m/day and an effective porosity of 1%.This suggests that the underlying weathered dolerite
aquifer is vulnerable to process water contamination from the ash dump system. The study illustrates the importance of a site conceptual model before the application of investigative
methods. Hence having a site conceptual model provides an excellent platform for hydraulic and transport estimation. The development of a site conceptual model enhanced the
understanding of flow and transport movement of the processed
water trough the ash dump, it also assisted as a beneficial tool to enhance ash dump management.
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Skryja, Marek. "Studie obnovy vybrané části vodovodní sítě." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2018. http://www.nusl.cz/ntk/nusl-372291.
Full textAbstract:
This diploma thesis deals with the study of the renewal of a selected part of the water supply network, specifically a section of the steel water supply line near the town of Velké Meziříčí. This study evaluates the current technical condition of the pipeline. Renovation is designed by selected rehabilitation technologies and renewal with the installation of a new pipeline. The thesis also describes the possible substitution of water transport during the shutdown of the part of the water supply network, including the mathematical model. Rehabilitation technologies are compared technically and economically. Also in terms of hydraulic parameters, using the EPANET 2.0 software application.
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Kavli, Christian K. "Simple Model Representation of Underbalanced Drilling Hydraulics and Control." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for teknisk kybernetikk, 2014. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-26104.
Full textAbstract:
Oil reservoirs can be sensitive to unfamiliar fluids such as drilling fluids. In order to prevent fluids to enter the formations surrounding the well, the well pressure can be lowered below the reservoir pressure, called underbalanced drilling. This technique calls for injecting of gas into the mud to lower the pressure, with additional inflow of oil and gas to the well as a result. This thesis evaluates current modelling of two-phase flow related to underbalanced drilling, and possible simplifications. Through investigation of simulation data, the current modelling based on first principles, is considered too complex compared to data of the key dynamics. To simplify the modelling, a black box system identification approach is used. By identifying solely from simulation data, low order models with good fit to validation data are obtained. Through testing, the models' validity are tested, and it is concluded that a number of simple models will be needed to represent the whole system given by the simulator. Models with specific orders are tested at different set points, and one model order produces good accuracy at all the operating points tested. This model is likely to be able to accurately represent the whole system with updated parameters.The accuracy of the simple models identified reveals simple system dynamics, and a PI controller is considered to be sufficient. The models are being used to tune the controller, and the controller perform great on set point changes. In addition, the controller is tested with an emulated connection, with satisfactory performance.
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Gajdušek, Jakub. "Technologický manipulátor udírny." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2010. http://www.nusl.cz/ntk/nusl-229150.
Full textAbstract:
This work designs overall structural design of technological manipulator of smoking- chamber, which serves to move the trolleys with food between smoking and chilling chamber. Chambers are connected in a single device. Trolleys are considered with full and uniformly distributed load. Work includes a 3D model of equipment and production documentation.
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Fólová, Zuzana. "Simulace povodňové vlny po protržení přehrady na Bílé Desné." Master's thesis, Česká zemědělská univerzita v Praze, 2016. http://www.nusl.cz/ntk/nusl-258478.
Full textAbstract:
The thesis deals with a creation of a model that imitates a flood wave and determining the flooded area after the rupture of the earth dam situated on the water flow Bílá Desná in The Liberec Region. It is not only a fictitious demonstration, but the actual application of a real flow wave caused by the destruction of the hydraulic dam from 1916 till the present state of the territory. The used input data were obtained from the ČÚZK and the terrain measurements. These data were processed in several programs, namely: HEC-GeoRAS and HEC-RAS. From the results of the model was determined the flooded area during peak flow and a model that portrays the development of the flood wave on the designed flow section. The results of this study enable to sketch the event which could occur if the rupture of the hydraulic dam did not occur in the 1916, but nowadays.
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Kayani, Omer Khaleeq, and Muhammad Sohaib. "Generic Simulation Model Development of Hydraulic Axial Piston Machines." Thesis, Linköpings universitet, Fluida och mekatroniska system, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-76575.
Full textAbstract:
This master thesis presents a novel methodology for the development of simulation models for hydraulic pumps and motors. In this work, a generic simulation model capable of representing multiple axial piston machines is presented, implemented and validated. Validation of the developed generic simulation model is done by comparing the results from the simulation model with experimental measurements. The development of the generic model is done using AMESim. Today simulation models are an integral part of any development process concerning hydraulic machines. An improved methodology for developing these simulation models will affect both the development cost and time in a positive manner. Traditionally, specific simulation models dedicated to a certain pump or motor are created. This implies that a complete rethinking of the model structure has to be done when modeling a new pump or motor. Therefore when dealing with a large number of pumps and motors, this traditional way of model development could lead to large development time and cost. This thesis work presents a unique way of simulation model development where a single model could represent multiple pumps and motors resulting in lower development time and cost. An automated routine for simulation model creation is developed and implemented. This routine uses the generic simulation model as a template to automatically create simulation models requested by the user. For this purpose a user interface has been created through the use of Visual Basic scripting. This interface communicates with the generic simulation model allowing the user to either change it parametrically or completely transform it into another pump or motor. To determine the level of accuracy offered by the generic simulation model, simulation results are compared with experimental data. Moreover, an optimization routine to automatically fine tune the simulation model is also presented.
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Lopez, Sabater Carlos Joaquin. "An empirical model of hydraulic roughness for overland flow." Diss., The University of Arizona, 2001. http://hdl.handle.net/10150/280353.
Full textAbstract:
This research has developed a method for estimating hydraulic roughness coefficients for overland flow models in a dynamic approach, to more effectively simulate runoff on natural, agricultural and urban slopes. The hydraulic roughness coefficients are then generated with a series of neural networks. First, a laboratory experiment was designed to explore the effects of soil microtopography, slope and Reynolds number on the magnitude of Darcy-Weisbach, Manning and Chezy roughness coefficients. It was found that three parameters were necessary to describe the soil surface microtopography. Neural networks developed in a preliminary phase were able to reproduce the roughness coefficients obtained in the laboratory experiment by using five predictor variables: bed slope, Reynolds number, and the three parameters used to describe the microtopography. However, these networks failed to generate roughness coefficients for different input variables (generalization). Second, more complex algorithms were developed as combinations of neural networks in parallel. The algorithm output, the sought hydraulic roughness estimate, was estimated with the arithmetic average of the individual network outputs. Results presented in this study demonstrate that combining multiple neural networks reduced the prediction error and improved on the generalization ability of the neural networks. It was also observed that the estimate accuracy was influenced by the characteristics of the dataset, and especially by the relationship between the roughness coefficient and Reynolds numbers. Finally, a field experiment was performed to explore the applicability of the algorithms. A numerical model based on the 1-D diffusion approximation to the Saint Venant equations was constructed, and two surface irrigations were performed to collect data to test the model estimates. The model was used under two scenarios: (1) with constant hydraulic roughness coefficients, and (2) using variable hydraulic roughness predicted with the algorithm. Discharge at the end of the plot and irrigation front advance estimated using both models matched the observations well. However, when using a variable hydraulic roughness, the front was initially delayed until there was a sufficient surface storage to push it forward. The methodology described in this research should be useful for 2-D overland flow models applied to natural slopes with unsteady rainfall.
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Howarth, D. A. "The hydraulic performance of scale model storm sewer junctions." Thesis, University of Manchester, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.355907.
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Almeida, Fernando Gomes de. "Model reference adaptive control of two axes hydraulic manipulator." Thesis, University of Bath, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.334573.
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Svatoš, Petr. "Technické a vodohospodářské řešení rekonstrukce hráze VD Ivanské jezero na Javornickém potoce." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2019. http://www.nusl.cz/ntk/nusl-392255.
Full textAbstract:
Water structure Ivanské jezero was built on the Javorník Creek back between 1905-1907. The main purpose of the dam was accumulation of high volumes of water and protection of the territory downstream. After the adjustment for higher flows on the river Kněžna in Rychnov nad Kněžnou, which was completed in 1937, the water structure lost the protective function. On the basis of an assessment made by Povodí Labe in 1993 - due to the low volume of the reservoir there is no flood wave transformation and already while flow rates greater than Q50 pass through dam, it results in overflowing the dam. To this date water structure Ivanské jezero is in very poor condition due to degradation of the binding material in the dam. The goal of the thesis is to propose a procedure for removal of the existing structure and the subsequent construction of the design and construction of a new – gravity, concrete dam. This work will contain technological removal process of current dam and possible usage options for the dam material. In the next step a new structure will be designed in the place of existing dam. After new design is completed there will be hydraulic assessment of the functional objects, hydrology and stability on the dam.
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Kapusta, Juraj. "Diagnostika stroje založena na modelech." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2021. http://www.nusl.cz/ntk/nusl-442841.
Full textAbstract:
The main idea is focused on the diagnostics of a specific hydraulic system, i.e. sensing the physical quantities of the hydraulic circuit with a tank and a centrifugal pump driven by an asynchronous motor. It is a system of pipes connected to the pump, where due to its work it creates a water flow and a pressure increase. In practice, this issue is also addressed in the energy and nuclear industries. Primary circuits in some cases cannot be designed or modified to be able measure locally the pressure value. It is necessary to measure this quantity indirectly - from the motor currents. The main idea of the work is to diagnose the system by an indirect method - specifically to detect the state of the hydraulic circuit (pressure, flow) from the values that we are able to measure and detect damage in advance. In the second part of the thesis is the application of the parts of a specific hydraulic system in the simulation environment MATLAB Simulink. The model of the hydraulic circuit contains mathematical-physical relations that simulate the course of the mentioned experiment. The results of the simulation are compared with the results of the experiment. The model also investigates the simulation of a fault condition, when we supply pressure pulsations to the hydraulic circuit. It is these changes in the hydraulic part that affect the characteristics of the pump and the asynchronous motor, so we are able to diagnose this system.
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Stříž, Jaroslav. "Hydraulické posouzení rázových jevů v jezové zdrži Střekov." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2019. http://www.nusl.cz/ntk/nusl-391918.
Full textAbstract:
The main aim of the thesis is to assess the origin of surge phenomena, primarily surge waves at the weir pool Střekov, using the selected methodology. The paper is divided into several parts. There is a brief introduction to the problematics and research of possible solution methods, followed by a verification of these methods on a physical model and finally an application of a numerical method for an assessment of the chosen locality.
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Berka, Ondřej. "Hydraulické posouzení vlivu revitalizace vodního toku na retenční kapacitu údolní nivy." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2015. http://www.nusl.cz/ntk/nusl-227525.
Full textAbstract:
Diploma thesis “Hydraulic Assessment of a Stream Revitalization Effect on a Floodplain Retention Capacity“ assess availability of revitalized stream and its floodplain to transform floods and compare determined values with transformed floods from model of technically modified stream, both by using coupling 1D/2D BASEMENT computational model. In the first part is overall introduction to research issue. In the second part the territory of interest is described and the hypothesis are set. In the third part are described input data, used tools, computational model, its making and computational versions. In the fourth part the hypothesis are evaluated. It was determined, that for in this thesis used terrain and hydrographs are floods smaller than Q20 transformed much more by revitalized stream and that technically modified stream can speed up the flood, floods Q50 and Q100 are more transformed by technically modified stream. For generalization of the results would be appropriate to make research on bigger ammount of case studies based on combination of 1D/2D and rainfall-runoff model.
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Lopez, Egea Marta. "Experimental and Numerical Modelling of Submerged Hydraulic Jumps at Low-Head Dams." Thesis, Université d'Ottawa / University of Ottawa, 2015. http://hdl.handle.net/10393/32345.
Full textAbstract:
This study, which includes both experimental and numerical-modelling components, investigates the potentially dangerous conditions that can often occur when low-head dams (or weirs) are overtopped and ‘submerged’-type hydraulic jumps subsequently form downstream of them. The combination of high local turbulence levels, air entrainment, and strong surface currents associated with submerged jumps pose a significant risk to safety of boaters and swimmers. In this study, a wide range of flow regimes and different experimental conditions (i.e. crest length and downstream apron elevation) were considered. The experimental phase involved physical model testing to determine: (i) the hydraulic conditions that govern submerged jump formation, and (ii) the hydrodynamic characteristics of the submerged vortex. The numerical model, developed using OpenFOAM, was validated with the obtained experimental data. This research seeks to help develop improved guidelines for the design and safe operation of low-head dams. The experimental phase of the study involved physical model testing to
determine: (i) the hydraulic conditions that govern submerged jump formation, and (ii) the hydrodynamic characteristics of the submerged vortex. The numerical modelling work involved using interFoam (OpenFOAM toolbox) for simulating the experimental results. InterFoam is an Eulerian 3-D solver for multiphase incompressible fluids that employs the Volume of Fluid approach (VOF) to capture the water-air interface. The developed numerical model was subsequently validated using the experimental data collected and processed by the author of this study.
The range of tailwater depths associated with submerged hydraulic jump
formation is dramatically reduced when a broad-crested weir is coupled with an elevated downstream apron, especially under high flow rate conditions. However sharp-crested weirs induced vortices which displayed reduced velocities and decreased spatial development, which were judged to be safer than broad crest lengths under the same discharge conditions. The classical formulation for the degree of submergence was not explicative when used to evaluate “how submerged the vortex was”. Consequently, a new normalized formulation which compares the local tailwater depth to the lower and upper tailwater limits for the submerged hydraulic jump is proposed. The numerical model developed for this study demonstrated the existence of residual turbulent kinetic energy at downstream sections located within the vortex’s extension, at instants coinciding with the presence of a fully formed roller. This turbulent energy is arguably responsible for the stationary nature of the vortex under constant flow conditions. Residual vertical and horizontal velocities at points located within the vortex’s domain are indicative of the existence of the free surface current.
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Matiaško, Dušan. "Modely a simulace pochodů bezemisního mini-exkavátoru s elektrickým pohonem." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2021. http://www.nusl.cz/ntk/nusl-442805.
Full textAbstract:
The diploma thesis dealt with a partial problem of conversion of the mini-excavator E19 by Bobcat with an internal combustion engine to emission-free propulsion. The main task was design and construction of electrical and hydraulic circuits focusing on the drive of a mini-excavator. The simulations verified the properties and behavior of the mini-excavator under different conditions and initial settings. The results were comfirmed by experimental measurements. The output of the simulations recommended adjustments to the values of individual parameters depending on the travel speed but also the efficiency of the entire machine.
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Liu, Jianxin. "A porosity-based model for coupled thermal-hydraulic-mechanical processes." University of Western Australia. Centre for Petroleum, Fuels and Energy, 2010. http://theses.library.uwa.edu.au/adt-WU2010.0113.
Full textAbstract:
[Truncated abstract] Rocks, as the host to natural chains of coupled thermal, hydraulic and mechanical processes, are heterogeneous at a variety of length scales, and in their mechanical properties, as well as in the hydraulic and thermal transport properties. Rock heterogeneity affects the ultimate hydro-carbon recovery or geothermal energy production. This heterogeneity has been considered one important and difficult problem that needs to be taken into account for its effect on the coupled processes. The aim of this thesis is to investigate the effect of rock heterogeneity on multi-physical processes. A fully coupled finite element model, hereinafter referred to as a porosity-based model (PBM) was developed to characterise the thermal-hydraulic-mechanical (THM) coupling processes. The development of the PBM consists of a two-staged workflow. First, based on poromechanics, porosity, one of the inherent rock properties, was derived as a variant function of the thermal, hydraulic and mechanical effects. Then, empirical relations or experimental results, correlating porosity with the mechanical, hydraulic and thermal properties, were incorporated as the coupling effects. In the PBM, the bulk volume of the model is assumed to be changeable. The rate of the volumetric strain was derived as the difference of two parts: the first part is the change in volume per unit of volume and per unit of time (this part was traditionally considered the rate of volumetric strain); and the second is the product of the first part and the volumetric strain. The second part makes the PBM a significant advancement of the models reported in the literature. ... impact of the rock heterogeneity on the hydro-mechanical responses because of the requirement of large memory and long central processing unit (CPU) time for the 3D applications. In the 2D PBM applications, as the thermal boundary condition applied to the rock samples containing some fractures, the pore pressure is generated by the thermal gradient. Some pore pressure islands can be generated as the statistical model and the digital image model are applied to characterise the initial porosity distribution. However, by using the homogeneous model, this phenomenon cannot be produced. In the 3D PBM applications, the existing fractures become the preferential paths for the fluid flowing inside the numerical model. The numerical results show that the PBM is sufficiently reliable to account for the rock mineral distribution in the hydro-mechanical coupling processes. The applications of the statistical method and the digital image processing technique make it possible to visualise the rock heterogeneity effect on the pore pressure distribution and the heat dissipation inside the rock model. Monitoring the fluid flux demonstrates the impact of the rock heterogeneity on the fluid product, which concerns petroleum engineering. The overall fluid flux (OFF) is mostly overestimated when the rock and fluid properties are assumed to be homogeneous. The 3D PBM application is an example. As the rock is heterogeneous, the OFF by the digital core is almost the same as that by the homogeneous model (this is due to that some fractures running through the digital core become the preferential path for the fluid flow), and around 1.5 times of that by the statistical model.
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Trasky, Trevor Ryan. "Hydraulic model calibration for the Girdwood, Alaska water distribution system." Thesis, Montana State University, 2008. http://etd.lib.montana.edu/etd/2008/trasky/TraskyT0508.pdf.
Full textAbstract:
The possible EPA promulgation of regulations requiring flushing programs for water distribution systems to regulate water age is encouraging many utilities to develop a better understanding of their systems. This usually involves the development of a hydraulic model. For the hydraulic model to be of use it must be calibrated using collected field data. Few established guidelines exist for utilities to perform such data collection and calibration. There are many different types of data that can be collected using many different methods. There are also various model calibration methods that can be used. This study sought to develop an optimized sampling plan and calibration method for a small utility that defines the best practice for data type, location, quantity, and collection conditions. A large quantity of many data types were collected at various locations in the system. Different methods were used to calibrate the model with various data sets and the model accuracy was evaluated using a second independent data set. The effect of model input parameter accuracy and pipe grouping during calibration on overall accuracy was also investigated. Data type, location, quantity, and collection conditions had an impact on calibration accuracy. High headloss data from fire flow tests provided better calibrations than low loss data from static pressures. Carefully selected test locations resulted in more efficient calibration than evenly distributed test locations. There was found to be a point of diminishing returns when investigating the amount of data used in calibration versus calibration accuracy. Uncalibrated model input parameters such as elevations and pump characteristics also had a significant impact on model calibration accuracy.
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Hodgson, Paul. "Theoretical model and dynamic simulation of variable fill hydraulic dynamometers." Thesis, University of Canterbury. Department of Mechanical Engineering, 1991. http://hdl.handle.net/10092/4487.
Full textAbstract:
The torque characteristics of variable fill hydraulic dynamometers
are investigated, particularly the phenomenon of self-emptying of
Froude F type machines under open loop control. An integrated one-dimensional
model is adapted from fluid coupling and torque converter
theory to cover the steady-state case, and extended to the non-linear
open loop dynamic cases by incorporating varying fluid fill and the
dynamic governing equations for dynamometers. Two feedback
systems are included to predict the closed loop behaviour of the
machines.
The effect of geometriC variations on the steady-state torque
capacity of dynamometers is given and the cause of the self-emptying
phenomenon determined. It is found that the increase in working
compartment fluid pressure with shaft speed leads to the fluid outflow
rate becoming greater than the supplied inflow rate. Thus the fluid fill
decreases. This phenomenon is further investigated using a dynamic
model, consisting of a system of first order differential equations. The
Adams-Bashforth Predictor Adams-Moulton Corrector numerical
method is used to solve the system of equations. In addition to the self-emptying
characteristic investigation, the differences between steady
state and dynamic model predictions and the system responses to
changes of set point and disturbances of its inputs (driving torque,
outflow valve position, fluid inflow rate) are studied.
To enable closed loop performance prediction, models of two
feedback system are incorporated: a back pressure water outlet valve
driven by a machine-speed oil-pump, and an electrohydraulic butterfly
valve governed by direct digital control. The latter model is used to
Investigate controller tuning around the dynamometer's operating
envelope. It is also subjected to input disturbances and the responses
compared to the open loop behaviour.
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Hodgson, P. G. "Theoretical model and dynamic simulation of variable fill hydraulic dynamometers." Thesis, University of Canterbury. Mechanical Engineering, 1991. http://hdl.handle.net/10092/6035.
Full textAbstract:
The torque characteristics of variable fill hydraulic dynamometers are investigated, particularly the phenomenon of self-emptying of Froude F type machines under open loop control. An integrated one-dimensional model is adapted from fluid coupling and torque converter theory to cover the steady-state case, and extended to the non-linear open loop dynamic cases by incorporating varying fluid fill and the dynamic governing equations for dynamometers. Two feedback systems are included to predict the closed loop behaviour of the machines.
The effect of geometric variations on the steady-state torque capacity of dynamometers is given and the cause of the self-emptying phenomenon determined. It is found that the increase in working compartment fluid pressure with shaft speed leads to the fluid outflow rate becoming greater than the supplied inflow rate. Thus the fluid fill decreases. This phenomenon is further investigated using a dynamic model, consisting of a system of first order differential equations. The Adams-Bashforth Predictor Adams-Moulton Corrector numerical method is used to solve the system of equations. In addition to the self-emptying characteristic investigation, the differences between steady state and dynamic model predictions and the system responses to changes of set point and disturbances of its inputs (driving torque, outflow valve position, fluid inflow rate) are studied.
To enable closed loop performance prediction, models of two feedback system are incorporated: a back pressure water outlet valve driven by a machine-speed oil-pump, and an electrohydraulic butterfly valve governed by direct digital control. The latter model is used to investigate controller tuning around the dynamometer's operating envelope. It is also subjected to input disturbances and the responses compared to the open loop behaviour.
43
Huang, Yuli. "Elastohydrodynamic model of hydraulic rod seals with various rod surfaces." Diss., Georgia Institute of Technology, 2014. http://hdl.handle.net/1853/53061.
Full textAbstract:
The reduction or elimination of leakage of hydraulic fluid from fluid power systems is considered a fundamental prerequisite for the expanded use of fluid power. There is also a need to reduce seal friction to both reduce energy dissipation and eliminate control problems. These seals are developed through empirical means at the present time, since the fundamental physics of seal operation has been unclear.
This research develops numerical models for analyzing reciprocating hydraulic rod seals with various rod surfaces. These models consist of coupled fluid mechanics, contact mechanics and deformation analyses. Both flooded and starved lubrication boundary conditions are applied.
For seals with a smooth rod and a plunge-ground rod, the model combines a 1-D finite volume Reynolds equation solver with a 2-D axisymmetric finite element deformation and static contact mechanics analyses, and a Greenwood-Williamson contact mechanics analysis with rod motion. Leakage and friction, along with sealing zone details with the plunge-ground rod are compared with those with the smooth rod. The influence of rod surface finish on seal performance is investigated and explained, under both flooded and starved conditions
For seals with a micro-patterned rod, the model consists of finite volume Reynolds equation solver, finite element deformation and static contact mechanics analyses and a Greenwood-Williamson dynamic contact mechanics analysis. This model is able to handle rod surface pattern with 3-dimensional geometrics. Simulations with different micro-pattern geometries are performed to analyze the fundamental mechanism of surface pattern effects on seal operation. Again, both flooded and starved conditions are applied and the results for both cases are compared and analyzed.
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Gomes, De Almeida Fernando. "Model reference adaptive control of a two axes hydraulic manipulator." Thesis, University of Bath, 1993. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.760644.
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Ydebäck, Niklas. "Grey Box Model of Leakage In Radial Piston Hydraulic Motors." Thesis, Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-84639.
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This report covers the work and results of the thesis project in Mechanical Engineering from Luleå university of technology performed by Niklas Ydebäck. The objective of the thesis project is to research if it is possible, with general principles of fluid flow between components and the corresponding geometric constraints between them and just a few channels of data, to model the leakage of a radial piston hydraulic motor. The model is of the grey box kind which makes use of both numerical and statistical methods together with known physical properties of a system in order to model the system. The unknown parameters of this system that are estimated using the least squares method are the three different gap heights of the system as well as the two different eccentricities in the system. The model contains the physical properties of the system, stated in equations for the leakage in the relevant lubrication interfaces, but no relational properties for the dynamics and affects between the individual lubricating interfaces. The model developed is due to the model generality together with the data quality accessible not able to model the system with reliable quality. The model is however able to capture the general trend of the leakage in the system over the applied time series datasets.Den här rapporten presenterar arbetsgången och resultatet av examensarbetet för en civilingenjörsexamen i Maskinteknik från Luleå tekniska universitet utförd av Niklas Ydebäck. Målet med examensarbetet är att utvärdera och undersöka om det är möjligt, med generella och vedertagna principer av fluidflöde mellan smorda komponenter tillsammans med de geometriska begränsningarna som hör dem till och några få kanaler av data, att modellera läckaget för en radialkolvsmotor. Modellen är en grålådemodell som med hjälp av numeriska och statistiska metoder och kända fysikaliska principer av ett system bildar en modell av systemet. De okända parametrarna av systemet som estimeras med hjälp av minsta kvadrat metoden är de tre olika typerna av spalthöjderna och de två olika eccentricitetstyperna som finns i systemets smorda kontakter. Modellen består av de fysikaliska egenskaperna i systemet, formerade i ekvationer för läckaget i de relevanta smorda kontakterna, men inga relationella egenskaper för dynamiken och effekterna mellan de olika smorda kontakterna. Den utvecklade modellen är på grund av den generella karaktären av modellen tillsammans med kvaliteten på den data som finns tillgänglig inte möjlig att modellera läckaget i systemet med tillräcklig noggrannhet. Modellen är trots detta kapabel att fånga de generella trender som återfinns i den uppmätta datan på läckaget för de applicerade dataseten.
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Attari, Jalal. "Shear layer behaviour in the near wake of a model gate." Thesis, Imperial College London, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.249309.
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Williams, Scott C. "Cavitation noise in a model spool valve." Thesis, Georgia Institute of Technology, 1998. http://hdl.handle.net/1853/20230.
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Armitage, Neil Philip. "A unit stream power model for the prediction of local scour." Thesis, Stellenbosch : Stellenbosch University, 2002. http://hdl.handle.net/10019.1/52716.
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Thesis (PhD)--Stellenbosch University, 2002.ENGLISH ABSTRACT: Local scour is the erosion of a riverbed resulting from the flow of the river around an obstacle. It is a principal cause of failure of bridges and other hydraulic structures. Current design practice relies on the use of empirical formulae that are often extremely inaccurate, or on the use of physical models that are very expensive. Recent advances in the power of microcomputers have however made numerical simulation increasingly attractive. One obstacle to numerical simulation though is that there is no general agreement on the concept of incipient motion, that critical point at which motion - and hence scour - begins. In this dissertation, the unit stream power model developed by Rooseboom (1992) is extended to handle the complex three-dimensional flow conditions that pertain close to the riverbed in the vicinity of an obstacle. The relationship between unit stream power (the dissipation function) and the Movability Number (the ratio of the shear velocity to the terminal settling velocity of the critical sediment particles) is clearly indicated. Since incipient motion is probabilistic in nature, a relationship was established between the Movability Number and the intensity of motion with allowance for bed-slope and relative depth. An extension of this work resulted in a new bed-load transportation equation that could be used to determine the rate of scour development. Physical modelling in a laboratory flume aided the selection of suitable critical conditions for the onset of scour. The usefulness of the above-mentioned relationships was then demonstrated through the construction of a simple mathematical model of scour and deposition around a structure. This model was used in conjunction with commercially available computational fluid dynamics (CFD) software to predict the scour potential around typical engineering structures. Physical model data was obtained for four situations, and the measured scour was compared with that predicted by the numerical model. There was reasonable agreement between the different models and such differences as there were could be readily attributed to constraints on the numerical model, in particular the lack of a free-surface routine and the coarseness of the grid. This dissertation has opened up a new method for the prediction of local scour that could be readily extended to include all types of scour. With the advent of increasingly fast computers, it could become a useful engineering tool that would assist engineers in the design of safe and cost-effective foundations for hydraulic structures.
AFRIKAANSE OPSOMMING: Plaaslike uitskuring is die erosie van 'n rivierbed as gevolg van vloei verby 'n obstruksie. Dit is 'n belangrike oorsaak van die swigting van brfïe en ander hidrouliese strukture. Bestaande ontwerppraktyk berus op empiriese vergelykings wat dikwels hoogs onakkuraat is, of op fisiese modelle, wat baie duur is. Numeriese simulasie het die afgelope tyd 'n al hoe meer aantreklike opsie geword danksy die snelle toename in die kapasiteit van mikro-rekenaars. 'n Struikelblok met numeriese simulasies is die gebrek aan konsensus oor die konsep van begin-van-beweging, daardie kritieke toestand waarby beweging en derhalwe uitskuring begin. In hierdie proefskrif is die eenheidstroomdrywing model, ontwikkel deur Rooseboom (1992), uitgebrei om die komplekse drie-dimensionele vloeitoestande, wat teenaan die rivierbodem verby 'n obstruksie heers,te hanteer. Die verwantskap tussen Eenheid Stroomdrywing (Dissipasiefunksie) en die Beweeglikheidsgetal (verhouding tussen sleursnelheid en die ewewigvalsnelheid van die kritieke sedimentpartikels ) is duidelik uitgewys. Aangesien begin van beweging probabilisties van aard is, is die verwantskap bepaal tussen die Beweeglikheidsgetal en die Intensiteit van Beweging, met voorsiening vir bodernhelling en relatiewe diepte. Verdere uitbreiding het gelei tot 'n nuwe bedvrag vervoervergelyking wat gebruik kan word om die tempo van uitskuring te bepaal. Kritieke toestande, waarby uitskuring begin, is met fisiese modelle in die laboratorium gekwantifiseer. Die bruikbaarheid van bogenoemde verbande is gedemonstreer deur die ontwikkeling van 'n eenvoudige wiskundige model van uitskuring en afsetting rondom 'n struktuur. Hierdie model is saam met bestaande kommersiële sagteware vir vloeidinamika berekenings (CFD) ingespan om uitskuringspotensiaal rondom tipiese ingenieurstrukture te voorspel. Fisiese modelmetings van uitskuring vanaf vier uitlegte is vergelyk met die numeries voorspelde waardes. Bevredigende ooreenkoms is gevind en verskille kon geredelik gewyt word aan beperkings van die numeriese model, veral die gebrek aan' n vryvlakroetine en die growwe maas. Die proefskrif stel 'n nuwe metode vir die voorspelling van uitskuring daar wat geredelik uitgebrei kan word na ander vorms van uitskuring. Met die ontwikkeling van al vinniger rekenaars kan dit 'n nuttige hulpmiddel vir ingenieurs word om veilige en koste-doeltreffende fondamente in waterlope te ontwerp.
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Wang, Cheng. "AN INTEGRATED HYDROLOGY/HYDRAULIC AND WATER QUALITY MODEL FOR WATERSHED-SCALE SIMULATIONS." Doctoral diss., University of Central Florida, 2009. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/2529.
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This dissertation presents the design of an integrated watershed model, WASH123D version 3.0, a first principle, physics-based watershed-scale model of integrated hydrology/hydraulics and water quality transport. This numerical model is comprised of three modules: (1) a one-dimensional (1-D) simulation module that is capable of simulating separated and coupled fluid flow, sediment transport and reaction-based water quality transport in river/stream/canal networks and through control structures; (2) a two-dimensional (2-D) simulation module, capable of simulating separated and coupled fluid flow, sediment transport, and reactive biogeochemical transport and transformation in two-dimensional overland flow systems; and (3) a three-dimensional (3-D) simulation module, capable of simulating separated and coupled fluid flow and reactive geochemical transport and transformation in three-dimensional variably saturated subsurface systems. The Saint Venant equation and its simplified versions, diffusion wave and kinematic wave forms, are employed for surface fluid flow simulations and the modified Richards equation is applied for subsurface flow simulation. The reaction-based advection-dispersion equation is used as the governing equation for water quality transport. Several physically and mathematically based numerical options are provided to solve these governing equations for different application purposes. The surface-subsurface water interactions are considered in the flow module and simulated on the basis of continuity of interface. In the transport simulations, fast/equilibrium reactions are decoupled from slow/kinetic reactions by the decomposition of reaction networks; this enables robust numerical integrations of the governing equation. Kinetic variables are adopted as primary dependent variables rather than biogeochemical species to reduce the number of transport equations and simplify the reaction terms. In each time step, hydrologic/hydraulic variables are solved in the flow module; kinetic variables are then solved in the transport module. This is followed by solving the reactive chemical system node by node to yield concentrations of all species. Application examples are presented to demonstrate the design capability of the model. This model may be of interest to environmental scientists, engineers and decision makers as a comprehensive assessment tool to reliably predict the fluid flow as well as sediment and contaminant transport on watershed scales so as to evaluate the efficacy and impact of alternative watershed management and remediation techniques prior to incurring expense in the field.Ph.D.
Department of Civil and Environmental Engineering
Engineering and Computer Science
Civil Engineering PhD
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Firoozfar, Ali Reza. "Rock scour in hydraulic laboratory analog scour models." Diss., University of Iowa, 2014. https://ir.uiowa.edu/etd/1456.
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Erosional processes of solid materials have been the focus of many researchers around the world. Erosion can commence within a wide range of material strengths depending on the amount of water-driven energy and material properties. Erosion could also occur due to Aeolian effects as well as chemical weathering but these forcings are not of the focus of this research. Instead, the focus here is on rock erosion in waterways and in particular downstream of dams.
Rock erosion mostly takes place at the downstream of dams where the water conveys through the spillbays from upstream to the downstream during an extreme event. This phenomenon threatens both the structural soundness of the dam with implications to the public safety. It usually occurs when the applied hydrodynamic forces (average and fluctuating) exceed the strength of the rock mass formation. Rock scour at the downstream of dams due to high velocity impinging jet is a complex and highly dynamic process. So a deeper understanding of the process is crucial to determine the rock scour rate and extent.
Hydraulic laboratory models have been employed to investigate hydraulic processes and proved to be reliable tools for testing soil/sediment erosion; however, the study of rock scour remains challenging. The prototype rock formation cannot be utilized in the laboratory models because the flowing water in the scaled model contains much less energy and exerts less forcing. On the other hand, the use of granular sediment (non-cohesive), as a standalone approach to mimic the rock formation is not a precise method, since it will most probably lead to inaccurate results.
The idea of using a mixture of granular and cohesive sediment is investigated here to adequately simulate the rock erosion process in the laboratory scaled models. The granular sediment represents the rock blocks while the cohesive additive is a binder to keep the granular sediment together.
The rock scour process can occur through four mechanisms; fracture failure, block removal, fatigue failure and abrasion. In this study, because the focus is on the hydrodynamic forcing effects on rock erosion, we assume that in the completely and intermittently jointed rock, erosion is mostly governed by fracture, block removal and fatigue failure. Abrasion is triggered by collisional effects and is not the focus here. So, we hypothesize that if the rock formation considered being pre-fractured, it can be simulated using a mixture of non-cohesive sediment with cohesive additive.
This method was utilized to assess the rock scour process at the downstream of the Priest Rapids Dam. The Priest Rapids Dam project was part of a series of projects that was conducted at IIHR-Hydroscience & Engineering at The University of Iowa and sponsored by the Public Utility District No. 2 of Grant County, Ephrata, Washington (GCPUD) to investigate juvenile salmonid migration at the Wanapum/Priest Rapids Development. It is a hydroelectric, concrete gravity, and mid-elevation dam owned and operated by Public Utility District No. 2 of Grant County, Washington (the "District").
To aid the District in their evaluation of fish passage, IIHR-Hydroscience & Engineering constructed comprehensive three-dimensional physical models of the forebay and tailrace of Priest Rapids Dam and a third model of spillbays 19-22 and powerhouse Unit 1 (sectional model).
As part of the last phase of the project, it was crucial to assess the effects of the newly designed fish bypass system on the downstream rock foundation scour. To investigate this process, the 1:64 Froude-based scale tailrace model of the dam was utilized. The mixture of gravel, bentonite clay, and water was employed to mimic the rock formation and simulate the bedrock scour process in the model. Series of preliminary experiments were conducted to find the optimum mixture of gravel, bentonite and water to accurately replicate an existing scour hole observed in the prototype tailrace. Two scenarios were considered. First, tests were conducted to estimate the scour potential downstream of the fish bypass, which is currently under construction. Second, the scour potential downstream of the dam was also assessed for the Probable Maximum Flood (PMF) with the fish bypass system running. Based on the model tests results and observations, the simulated bedrock (mixture of gravel and cohesive bentonite) was able to replicate the rock scour mechanisms, i.e. fracture process, block removal and fatigue observed in nature. During the fish bypass scour tests, it was observed that the erosion process occurs in the form of block removal and fatigue failure.
During the PMF scour test, instead, it was observed that the mixture is eroded in chunks of substrate. This process can be representative of fracture failure in rock which occurs when the induced pressure fluctuation exceeds the fracture strength or equivalently toughness of the rock. In the preliminary phase of this work it was recognized that a prerequisite for replicating the processes in the laboratory is the proper preparation of the mixture. There is limited information available in the literature about how much cohesive additive is required to simulate the erosional strength of the prototype rock formation.
For this reason, in this study the effort has been made to develop a method to simulate the rock formation for studying rock scour process in the laboratory analog scaled models. To simulate the bedrock formation, various combination of granular sediment (gravel), cohesive additive, and water were created and tested. Choosing an appropriate cohesive additive concentration is critical and nearly a balancing act. An appropriate cohesive additive concentration should be cohesive enough to bind the material and not too strong to be eroded by the flowing water in the scaled models. Moreover, its properties should not change over time. Various cohesive additives can be mentioned i.e. kaolin clay, bentonite clay, cement, grease, paraffin wax. Among all of them, bentonite clay was chosen as the appropriate cohesive additive due to its swelling characteristic. When bentonite is mixed with granular sediment, it is restricted by the non-cohesive sediment grains. The bentonite expands to fill the voids and forms a tough, leathery mineral mastic through which water cannot readily move.
In order to assess the erodibility of the mixture the Jet Erosion Test (JET) apparatus was used. The JET apparatus is a vertical, submerged, circular, turbulent impinging jet which is widely accepted and utilized to assess cohesive soil erosion through flow impingement. There are devices such as flumes which could be effectively used for bank erosion where the flow shear action is prevalent. In this study, it was sought important that the forcing replicated in the experiments was of the same nature (normal impinging forcing instead of shear forcing) as observed in the downstream end of a dam. For this reason, JET was chosen as it provided a larger range of stresses (ranging between 100-1000 Pa) comparing to the flume device. The apparatus was designed based on the device developed by Hanson and Hunt (2007) and built at the IIHR-Hydroscience & Engineering.
Various replicate samples were made with different combinations of gravel, sodium bentonite clay, and water. To determine the erosional strength of the samples (critical stress) they were tested using the JET apparatus. The critical stress was determined as the stress associated with zero eroded mass. The results revealed that the erosional strength of the simulated bedrock mixtures highly depends on the amount of adhesive component (bentonite clay). The mixtures with the higher percentage of bentonite clay are less susceptible to erosion. The erosion threshold plot - similar to Annandale's plot - for the simulated bedrock mixtures was developed.
Using the erosional strength of the simulated bedrock mixtures, a step-by-step systematic method was developed to determine the optimum combination of weakly cohesive substrate in order to simulate the strength of the prototype bedrock. The method is based on the Annandale's erodibility index method and requires information about the prototype bedrock strength (erodibility index). The method is explained in conjunction with the Priest Rapids Dam project example.
The old trial and error method to establish an optimum weakly cohesive substrate is costly and time consuming especially in the case of large scale laboratory models. Also, the applicability of the method would be questionable when there is not enough information or a past data set that can be used as a baseline (witness) test. The new method eliminates these problems and the optimum mixture can be established using the geological information of the prototype bedrock formation.