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Arcot, Ramakant P. "Computer simulation of the Bristol compressor suspension system dynamics." Thesis, This resource online, 1993. http://scholar.lib.vt.edu/theses/available/etd-09052009-040832/.
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Raubenheimer, Gert. "Vibration excitation of axial compressor rotor blades." Thesis, Stellenbosch : Stellenbosch University, 2011. http://hdl.handle.net/10019.1/17987.
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Thesis (MScEng)--Stellenbosch University, 2011.ENGLISH ABSTRACT: Turbomachines are exposed to several environmental factors which may cause failure of components. One of these factors, high cycle fatigue, is often caused by blade utter. This thesis forms part of a project of the European Seventh Framework Programme (FP7), called project Future. Project Future is doing theoretical and experimental investigation into the occurrence of utter in turbomachinery. The objective of this thesis was to evaluate the effectiveness of a gas injection system as a means of exciting vibrations on the rst stage rotor blades of a compressor. Unsteady simulations of the excitation velocity perturbations were performed in the Computational Fluid Dynamics (CFD) software, Numeca FINE/Turbo. Experimental testing on the in-house Rofanco compressor test bench, using one prototype of the 15 injector system, provided data that was used to implement boundary conditions and to verify certain aspects of the unsteady simulation results. The simulation results revealed the following: the injector bypass frequency was so dominant that the excitation frequency was hardly detectable in the majority of cases. Furthermore, several secondary frequencies were consistently present. The injector bypass frequency, as well as the secondary frequencies, occurred as a result of the convolution of Fast Fourier Transforms. While the injector bypass frequencies can theoretically be eliminated, it will not be possible to eliminate the secondary frequencies from the blade response. In conclusion, according to the CFD results, it will not be possible to excite a single excitation frequency by making use of a nite number of gas injector vibration exciters.
AFRIKAANSE OPSOMMING: Turbomasjiene word onderwerp aan verskeie omgewingsfaktore wat falings van komponente kan veroorsaak. Een van hierdie faktore, naamlik hoëfrekwensie vermoeidheid, word onder andere veroorsaak deur lem adder. Hierdie tesis is deel van 'n projek in die Sewende Europese Raamwerk Program (European Seventh Framework Programme - FP7), projek Future. Projek Future doen teoretiese en eksperimentele ondersoek na die voorkoms van lemfl adder in turbomasjienerie. Die doelwit van hierdie tesis was om die effektiwiteit van 'n gasinspuiter vibrasie-opwekkingstelsel te evalueer, deur gebruik te maak van onbestendige simulasie in die berekenings vloei-meganika sagtewarepakket, Numeca FINE/Turbo. Eksperimentele toetswerk op die plaaslike Rofanco kompressortoetsbank, met 'n prototipe van die 15 inspuiter stelsel, het inligting verskaf wat gebruik is om die inlaattoestande te spesi seer en simulasieresultate te korreleer. Die simulasieresultate het getoon dat die frekwensie waarteen 'n lem by die inspuiters verbybeweeg, so prominent is, dat dit in die meerderheid van gevalle baie meer prominent is as die opwekkingsfrekwensie. Verder was daar ook deurgaans 'n aantal sekondêre frekwensies teenwoordig. Die teenwoordigheid van die inspuiter verbybeweeg frekwensie en die sekondêre frekwensies is die resultaat van die konvolusie van Vinnige Fourier Transforme. Alhoewel dit in teorie moontlik sal wees om die inspuiter verbybeweeg frekwensie te elimineer, is dit onmoontlik om die sekondêre frekwensies uit die lem vibrasie te elimineer. Ter opsomming, volgens die berekenings vloei-meganika resultate, is dit nie moontlik om met 'n stelsel van 'n eindige aantal inspuiters, 'n enkele vibrasie frekwensie op te wek nie.
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Holzinger, Felix [Verfasser]. "Coupling of tip leakage flow and blade vibration in transonic compressors : Mechanism and countermeasures / Felix Holzinger." Aachen : Shaker, 2018. http://d-nb.info/1159835063/34.
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Rose, John A. "The experimental characterization of the dynamics of a reciprocating freon compressor system." Thesis, This resource online, 1994. http://scholar.lib.vt.edu/theses/available/etd-12302008-063244/.
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Arzina, Dina. "Vibration analysis of compressor blade tip-rubbing." Thesis, Cranfield University, 2011. http://dspace.lib.cranfield.ac.uk/handle/1826/7109.
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There has been a significant increase in air traffic volume, particularly over the past twenty years. In order to cope with this increase in demand, it has been necessary to increase the efficiency of aircraft engines. Over the years, this has been achieved by reducing the clearance between blade tips and the engine casing. As a consequence of the reduced clearance, tip-rubbing frequently occurs in the engine during operation.
The primary aim of this project is to address the vibrations involved in a tip-rubbing phenomenon when a blade of the Intermediate Pressure (IP) compressor in a Trent 900 engine interacts with the casing. Current trends towards blade optimisation tend to make the blade thinner and thus more flexible; therefore, it is very important to be able to successfully predict and prevent nonlinear response of a blade when tip-rubbing occurs. Current literature on the study of nonlinear vibration of a blade in a tip-rub event is limited; this project is understood to be the first to attempt an understanding of the issue.
In this thesis, analytical models are presented that predict the nonlinear responses of rotor-stator interactions. These are helpful in understanding nonlinear parameters that can have an effect on the system response. Simulations were started by determining the stresses in the blade due to centrifugal rotation. Resonant frequencies of the blade were determined by modal analysis. Finally, the tip-rubbing event was simulated. The results were used to output frequency response curves which were used to identify if the blades were behaving nonlinearly as a result of tip-rubbing.
The primary conclusion from this project is that tip-rubbing can excite nonlinear vibration in the compressor blades. However, the simulation results were affected adversely by hourglassing of the casing segments and should not be considered completely accurate.
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Murphy, William P. "High-speed blade vibration in a transonic compressor." Thesis, Monterey, Calif. : Naval Postgraduate School, 2008. http://handle.dtic.mil/100.2/ADA483477.
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Thesis (M.S. in Engineering Acoustics)--Naval Postgraduate School, June 2008.Thesis Advisor(s):Hobson, Garth V. ; Baker, Steven. "June 2008." Description based on title screen as viewed on August 26, 2008. Includes bibliographical references (p. 33). Also available in print.
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Stasolla, Vincenzo. "Numerical analysis of aerodynamic damping in a transonic compressor." Thesis, KTH, Skolan för industriell teknik och management (ITM), 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-264359.
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Aeromechanics is one of the main limitations for more efficient, lighter, cheaper and reliable turbomachines, such as steam or gas turbines, as well as compressors and fans. In fact, aircraft engines designed in the last few years feature more slender, thinner and more highly loaded blades, but this trend gives rise to increased sensitivity for vibrations induced by the fluid and result in increasing challenges regarding structural integrity of the engine. Forced vibration as well as flutter failures need to be carefully avoided and an important parameter predicting instabilities in both cases is the aerodynamic damping. The aim of the present project is to numerically investigate aerodynamic damping in the first rotor of a transonic compressor (VINK6). The transonic flow field leads to a bow shock at each blade leading edge, which propagates to the suction side of the adjacent blade. This, along with the fact that the rotating blade row vibrates in different mode shapes and this induces unsteady pressure fluctuations, suggests to evaluate unsteady flow field solutions for different cases. In particular, the work focuses on the unsteady aerodynamic damping prediction for the first six mode shapes. The aerodynamic coupling between the blades of this rotor is estimated by employing a transient blade row model set in blade flutter case. The commercial CFD code used for these investigations is ANSYS CFX. Aerodynamic damping is evaluated on the basis of the Energy Method, which allows to calculate the logarithmic decrement employed as a stability parameter in this study. The least logarithmic decrement values for each mode shape are better investigated by finding the unsteady pressure distribution at different span locations, indication of the generalized force of the blade surface and the local work distribution, useful to get insights into the coupling between displacements and consequent generated unsteady pressure. Two different transient methods (Time Integration and Harmonic Balance) are employed showing the same trend of the quantities under consideration with similar computational effort. The first mode is the only one with a flutter risk, while the higher modes feature higher reduced frequencies, out from the critical range found in literature. Unsteady pressure for all the modes is quite comparable at higher span locations, where the largest displacements are prescribed, while at mid-span less comparable values are found due to different amplitude and direction of the mode shape. SST turbulence model is analyzed, which does not influence in significant manner the predictions in this case, with respect to the k-epsilon model employed for the whole work. Unsteady pressure predictions based on the Fourier transformation are validated with MATLAB codes making use of Fast Fourier Transform in order to ensure the goodness of CFX computations. Convergence level and discrepancy in aerodamping values are stated for each result and this allows to estimate the computational effort for every simulation and the permanent presence of numerical propagation errors.Aeromekanik är en av huvudbegränsningarna för mer effektiva, lättare, billigare och mer pålitliga turbomaskiner, som ångturbiner, gasturbiner, samt kompressorer och fläktar. I själva verket har flygplansmotorer som designats under de senaste åren har fått tunnare och mer belastade skovlar, men denna trend ger upphov till ökad känslighet för aeromekaniska vibrationer och resulterar i ökande utmaningar när det gäller motorns strukturella integritet. Aerodynamiskt påtvingade vibrationer såväl som fladder måste predikteras noggrant för att kunna undvikas och en viktig parameter som förutsäger instabilitet i båda fallen är den aerodynamiska dämpningen. Syftet med det aktuella projektet är att numeriskt undersöka aerodynamisk dämpning i den första rotorn hos en transonisk kompressor (VINK6). Det transoniska flödesfältet leder till en bågformad stötvåg vid bladets främre kant, som sprider sig till sugsidan på det intilliggande bladet. I och med detta, tillsammans med det faktum att den roterande bladraden vibrerar i olika modformer och detta inducerar instationära tryckfluktuationer, syftar detta arbete på att utvärdera flödesfältslösningar för olika fal. I synnerhet fokuserar arbetet på prediktering av den instationära aerodynamiska dämpningen för de första sex modformen. Den aerodynamiska kopplingen mellan bladen hos denna rotor uppskattas genom att använda en transient bladradmodell uppsatt för fladderberäkningen. Den kommersiella CFD-koden som används för denna utredning är ANSYS CFX. Aerodynamisk dämpning utvärderas med hjälp av energimetoden, som gör det möjligt att beräkna den logaritmiska minskningen som används som en stabilitetsparameter i denna studie. De minsta logaritmiska dekrementvärdena för varje modform undersöks bättre genom att hitta den ostadiga tryckfördelningen på olika spannpositioner, som är en indikering av den lokala arbetsfördelningen, användbar för att få insikt i kopplingen mellan förskjutningar och därmed genererat ostabilt tryck. Två olika transienta metoder används som visar samma trend för de kvantiteter som beaktas med liknande beräkningsinsatser. Den första modformen är den enda med en fladderrisk, medan de högre modformerna har högre reducerade frekvenser, och ligger utanför det kritiska intervallet som finns i litteraturen. Instationärt tryck för alla moder är ganska jämförbart på de högre spannpositioner, där de största förskjutningarna föreskrivs, medan runt midspannet finns mindre jämförbara värden på grund av olika amplitud och riktning för modformen. SSTturbulensmodellen analyseras, som i detta fall inte påverkar predikteringen på ett betydande sätt. Det predikterade instationära trycket baserad på Fourier-transformationen valideras med MATLAB-koder som använder sig av Fast Fourier Transform för att säkerställa noggrannheten hos CFX-beräkningar. Konvergensnivå och skillnader i aerodämpningsvärden anges för varje resultat och detta gör det möjligt att uppskatta beräkningsinsatsen för varje simulering och uppskatta utbredningen av det numeriska felet.
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Rankle, Hugo Elias Camargo. "Acoustic prediction and noise control of a refrigeration compressor." Thesis, This resource online, 1995. http://scholar.lib.vt.edu/theses/available/etd-09052009-040840/.
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Brandsen, Jacobus Daniel. "Prediction of axial compressor blade vibration by modelling fluid-structure interaction." Thesis, Stellenbosch : Stellenbosch University, 2013. http://hdl.handle.net/10019.1/85616.
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Thesis (MScEng)-- Stellenbosch University, 2013.ENGLISH ABSTRACT: The Council for Scientific and Industrial Research has developed a vibration excitation system. The system is designed to excite the rotor blades of an axial compressor in the specified vibration mode and at the specified frequency. The vibration excitation system was tested on Stellenbosch University’s Rofanco compressor test bench. A two-way staggered fluid-structure interaction (FSI) model was created that was capable of simulating the vibration of the rotor blades excited by the system. The results of the FSI model were verified using available experimental data. It was concluded that the FSI model is able to recreate the vibration excited by the system to within the desired level of accuracy. In addition, the results of the FSI model showed that the vibration excitation system should be able to excite the blades in the selected vibration mode and at the selected frequency provided that the excitation frequency is close the natural frequency of the first bending mode. The results also suggested that a transient computational fluid dynamics model should be sufficient for the prediction of the aerodynamic forces acting on the rotor blades. Furthermore, a one-way staggered FSI model should be adequate for calculating the motions of the blades.
AFRIKAANSE OPSOMMING: Die Wetenskaplike en Nywerheidnavorsingsraad het ’n vibrasie-opwekkingstelsel ontwerp om die rotorlemme van ’n aksiaalvloei kompressor in die gespesifiseerde vibrasiemodus en teen die gespesifiseerde frekwensie op te wek. Die vibrasieopwekkingstelsel is met behulp van die Universiteit Stellenbosch se Rofanco kompressortoetsbank getoets. Daarna is ’n tweerigting vloeistof-struktuur-interaksie model geskep om die vibrasie van die rotorlemme, wat deur die stelsel opgewek is, te simuleer. Beskikbare eksperimentele data is gebruik om die resultate van die vloeistof-struktuur-interaksie model te bevestig. Die gevolgtrekking is gemaak dat die model wél die vibrasie van die lemme met die nodige akkuraatheid kan simuleer. Die resultate van die vloeistof-struktuur-interaksie model toon ook dat die stelsel die lemme in die gekose vibrasiemodus en teen die gekose frekwensie behoort te kan opwek, solank die opwekkingsfrekwensie na aan die natuurlike frekwensie van die eerste buigmodus is. Voorts dui die resultate daarop dat ’n berekeningsvloeimeganika model die aërodinamiese laste van die lemme sal kan voorspel. ’n Eenrigting vloeistof-struktuur-interaksie model behoort voldoende te wees om die beweging van die rotorlemme te bereken.
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Muhammad, Moosa. "Numerical investigation of self-excited vibrations of a compressor cascade /." Stockholm, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-507.
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Lackner, Matthew 1980. "Vibration and crack detection in gas turbine engine compressor blades using Eddy current sensors." Thesis, Massachusetts Institute of Technology, 2003. http://hdl.handle.net/1721.1/28895.
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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, September 2004.Includes bibliographical references (p. 97).
(cont.) in the ECS signal, no definitive method for sensing blade vibration using an ECS has yet been developed.
High cycle fatigue (HCF) cracks generated by compressor blade vibrations are a common source of failure in gas turbine engines. Current methods for crack detection are costly, time consuming, and prone to errors. In-situ blade vibration detection would help operators avoid critical engine speeds, and help infer the presence of cracks via a change in the mode of a blade. Blade vibrations can be detected using non-contacting sensors like optical sensors, or contacting sensors like strain gauges. These methods have drawbacks that make them poorly suited for installation in a gas turbine engine. Eddy Current Sensors (ECS) have numerous advantages over other vibration detection methods. This thesis aims to use ECS's for vibration detection. Testing was performed in a spin pit rig in the Gas Turbine Lab at the Massachusetts Institute of Technology. The rig contained a rotor on which three test blades spun, and strain gauge and ECS data were extracted from the rig. Magnet arrays were used to provide an excitation force to the blades, causing them to vibrate as they were spinning. Force hammer testing was used to determine the resonant frequencies and mode shapes of the test blades, as well as transfer functions from the strain gauges to the blade tip acceleration. These transfer functions allowed for independent knowledge of the blade vibration behavior. The case of a cracked blade was also considered. Estimates were performed to determine the proper location and length of a crack in the test blade. A 10 mm edge crack was created in a test blade. The crack was found to lower the resonant frequency of the first torsion mode of the blade by 0.2%, and to alter the transfer function between strain and tip acceleration. While some evidence of the blade vibration appears
by Matthew Lackner.
S.M.
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Osburn, Nicholas Glen. "Implementation of a two probe tip-timing technique to determine compressor blade vibrations." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2000. http://handle.dtic.mil/100.2/ADA381876.
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Thesis (M.S. in Aeronautical Engineering)--Naval Postgraduate School, June 2000.Thesis advisors: Shreeve, Raymond P. "June 2000." Includes bibliographical references (p. 41). Also available online.
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Milligan, William James. "The design of a control system for the mitigation of vibration in variable speed screw compressor systems." Thesis, Glasgow Caledonian University, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.547435.
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RAMOS, JOSÉ DIVAL PASTOR. "DESENVOLVIMENTO DE UM SISTEMA MULTICANAL PARA ANÁLISE DE PULSAÇÃO DE PRESSÃO EM COMPRESSORES ALTERNATIVOS VISANDO A MANUTENÇÃO PREDITIVA." Escola Politécnica / Instituto de Matemática, 2006. http://repositorio.ufba.br/ri/handle/ri/21587.
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A necessidade de novas metodologias para análise e monitoramento de compressores alternativos motivou o desenvolvimento de um sistema digital multicanal com capacidade de medir diferentes grandezas simultaneamente. Como base para este trabalho escolheu-se medir pressão dinâmica, vibração e deslocamento do pistão. O desenvolvimento deste trabalho dentro de um curso de Mecatrônica produziu um sistema simples e eficiente cujos resultados experimentais, apresentados sob a forma de gráficos e dados de desempenho, confirmaram os defeitos introduzidos artificialmente. Isto permitiu validar o Sistema de Diagnóstico de Compressores Alternativos (SDCA) e demonstrou o quanto este recurso é poderoso para o diagnóstico de defeitos, tanto nos componentes da parte de compressão (fluid end) quanto nos de acionamento (power end). Estas informações, transformadas em recomendações de reparo, serão a base para uma atuação preditiva dos setores de Planejamento de Manutenção.
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Gamal, Eldin Ahmed Mohamed. "Analytical and experimental evaluation of the leakage and stiffness characteristics of high pressure pocket damper seals." Thesis, Texas A&M University, 2003. http://hdl.handle.net/1969.1/16.
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This thesis presents numerical predictions for the leakage and direct stiffness coefficients of pocket damper seals. Modifications made to earlier flow-prediction models are discussed. Leakage and static pressure measurements on straight-through and diverging configurations of eight-bladed and twelve-bladed seals were used for code validation and for calculation of seal discharge coefficients. Higher than expected leakage rates were measured in the case of the twelve-bladed seal, while the leakage rates for the eight-bladed seals were predicted reasonably accurately. Results are presented for shake tests conducted on the seals at pressures of up to 1000 Psi (6.90 MPa). Test variables included pressure drop across the seals and rotor speed. The experimentally obtained stiffness coefficients are compared to results of a rotordynamic damper seal code, which uses the corrected mass flow-rate calculation method. Results show that the code under-predicts the magnitude of the seal's stiffness for most test cases. However, general trends in the frequency dependency of the direct stiffness are more accurately predicted. The expectation of high values of negative stiffness in diverging seals is confirmed by the results, but the frequency at which the sign of the stiffness becomes positive is considerably lower than is predicted. In addition to presenting high-pressure test data, this thesis also attempts to provide some insight into how seal parameters can be modified to obtain desired changes in seal stiffness.
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Bailie, Samuel Todd. "Effects of Inlet Guide Vane Flow Control on Forced Response of a Transonic Fan." Diss., Virginia Tech, 2003. http://hdl.handle.net/10919/11056.
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The main contributor to the high-cycle fatigue of compressor blades is the response to aerodynamic forcing functions generated by an upstream row of stators or inlet guide vanes. Resonant response to engine order excitation at certain rotor speeds is especially damaging. Studies have shown that flow control by trailing edge blowing (TEB) can reduce stator wake strength and the amplitude of the downstream rotor blade vibrations generated by the unsteady stator-rotor interaction. In the present study, the effectiveness of TEB to reduce forced blade vibrations was evaluated in a modern single-stage transonic compressor rig. A row of wake generator (WG) vanes with TEB capability was installed upstream of the fan blisk, the blades of which were instrumented with strain gages. Data was collected for varied TEB conditions over a range of rotor speed which included one fundamental and multiple harmonic resonance crossings. Sensitivity of resonant response amplitude to full-span TEB flowrate, as well as optimal TEB flowrates, are documented for multiple modes. Resonant response sensitivity was generally characterized by a robust region of substantial attenuation, such that less-than-optimal TEB flowrates could prove to be an appropriate design tradeoff. The fundamental crossing amplitude of the first torsion mode was reduced by as much as 85% with full-span TEB at 1.1% of the total rig inlet flow. Similar reductions were achieved for the various harmonic crossings, including as much as 94% reduction of the second leading edge bending mode resonant response using 0.74% of the rig flow for full-span TEB. At least 32% reduction was achieved for all modal crossings over the broad flow range of 0.5 to 0.9% of the rig flow. Thus the results demonstrate the modal- and flowrate-robustness of full-span TEB for reducing forced response in a modern, closely-spaced transonic compressor. Reduced spanwise TEB coverage was generally found to provide less peak reduction. Widely varying sensitivities of the vibration modes to the spanwise TEB distribution were also noted. While the second chordwise mode experienced roughly the same maximum response reduction of 80% for all of the spanwise TEB configurations, some other modes were amplified from the baseline case under part-span TEB conditions. Part-span TEB was thus found to be less modally-robust than full-span TEB.Ph. D.
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Rangel, Sergio de Camargo. "Análise por elementos finitos da junta de vedação e dinâmica de um compressor hermético." Universidade de São Paulo, 2017. http://www.teses.usp.br/teses/disponiveis/18/18149/tde-13082017-230137/.
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Essa tese tem o objetivo modelar um subconjunto de peças de um compressor hermético de refrigeração idealizado utilizando um programa de elementos finitos para estudar a pressão de contato na junta da placa de válvulas com e sem pressão de gás refrigerante. Nessa pesquisa também se faz a modelagem dinâmica da bomba de um compressor acadêmico com vistas a estudar a vibração gerada durante seu funcionamento. No estudo da junta de vedação se faz um modelo geométrico do conjunto cabeçote e juntas com um programa CAD. A partir da geometria do subconjunto um modelo físico é construído no ANSYS®, que leva em consideração as diferentes propriedades dos materiais do conjunto cabeçote e juntas, inclusive a não linearidade do material da junta. São feitas simulações aplicando diferentes valores de força normal nos parafusos do cabeçote. No estudo de vibração do compressor faz-se o modelo de CAD da bomba de onde se obtém seu peso e propriedades de inércia. A matriz de rigidez do sistema de suspensão da bomba é calculada e se faz a análise modal da bomba. Os resultados das análises de pressão de contato foram mostrados através de gráficos da normal closure e da normal pressure da junta. Eles indicam de forma clara as regiões de baixa pressão de contato aplicada pelas peças que estão ou deveriam estar comprimindo a junta de vedação, que seriam regiões de falhas. Na análise dinâmica da bomba do compressor, é calculada a matriz de rigidez total do sistema com as molas de suspensão, levando em consideração a rigidez compressiva, de flexão e cisalhante das molas. Com a solução do modelo dinâmico criado, calcula-se a matriz dinâmica, a matriz modal normalizada, a matriz de frequências características, o deslocamento X → da bomba e também as energias cinética e potencial da bomba devido às forças de agitação. O modelo de elementos finitos da junta da placa de válvulas tem resultados coerentes e o modelo dinâmico da bomba fornece vários resultados para a análise de vibração de compressores.This thesis has as objective to model a subset of parts of an idealized hermetic compressor for refrigeration using a program of finite elements intended to study the contact pressure on the valve plate gasket with and without pressure from the refrigerant gas. In this research a dynamic modelling of an academic compressor pump is also made with the aim of studying the vibration generated during its functioning. In the study of the sealing gasket, a geometric model of the cylinder head and gasket assembly is made by using a CAD program. From the geometric of the subset a physical model is built on the ANSYS®, which takes into account the different properties of the cylinder head and gasket assembly materials, including the non-linearity of the gasket material. Simulations are made by applying different normal force values on the cylinder head screws. In the compressor vibration study, a CAD pump model is made, thus obtaining its weight and inertia properties. The stiffness matrix of the pump suspension system is calculated and a modal analysis of the pump is made. The results from the contact pressure analyses were shown through \"normal closure\" and \"normal pressure\" charts of the gasket. They show in clear form the low contact pressure regions applied by the parts that are or should be compressing the sealing gasket, which would the regions of failures. In the dynamic analysis of the compressor pump, the total stiffness matrix of the system is calculated with the suspension springs, taking into account the compressive, flexural and shearing rigidities of the springs. With the solution of the dynamic model created, the following are calculated: the dynamic matrix, the normalized modal matrix, the characteristics frequency matrix, the X → displacement from the pump, as well as the kinetic and potential energy of the pump due to shaking forces. The finite elements model of the valve plate gasket has coherent results and the dynamic model of the pump provides various results for the analysis of the compressor vibration.
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Lei, Lei. "Étude des matériaux poreux thermo compressés pour la modélisation des écrans acoustiques automobiles." Thesis, Compiègne, 2018. http://www.theses.fr/2018COMP2428/document.
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Ce travail a été réalisé dans le cadre du projet EcOBEx, qui consiste à réduire le bruit du groupe motopropulseur rayonné à l'extérieur par l'ajout d'écrans acoustiques dans le compartiment moteur du véhicule. Les écrans acoustiques sont fabriqués par thermocompression de matériaux poreux uniformes. Les propriétés et l'épaisseur du matériau évoluent en fonction du degré de compression subit par le matériau. L'objectif de ce travail est de proposer des lois pour prédire l'évolution des propriétés des matériaux à partir du taux de compression et de leurs valeurs initiales avant compression. Dans un premier temps, on s'intéresse aux paramètres du modèle de fluide équivalent de Johnson-Champoux-Allard-Lafarge (JCAL) : porosité, résistivité au passage d'air, tortuosité, longueurs caractéristiques visqueuse et thermique, perméabilité thermique statique. Des expressions analytiques sont proposées pour prédire la variation de ces paramètres en fonction de la compression. Elles sont développées à partir d'un modèle de matériaux fibreux à fibres cylindriques où les variations d'orientation des fibres induites par la thermocompression peuvent être prises en compte. Les résultats sont en bon accord avec les mesures effectuées sur deux types de matériaux (mousse à cellules ouvertes et fibreux). Un modèle empirique généralisé est finalement proposé pour la résistivité au passage d'air. Dans un deuxième temps, on s'attache aux paramètres élastiques dont la connaissance est essentielle pour prendre en compte la vibration du squelette. La méthode expérimentale quasistatique est d'abord appliquée pour étudier l'évolution du module de Young par rapport au taux de compression pour les fibres et les mousses. Une loi de puissance est alors proposée pour prédire ces variations. Enfin, une méthode inverse pour estimer les propriétés élastiques d'un matériau poroélastique orthotrope à partir d'une mesure vibratoire d'un écran tricouche thermo comprimé est proposée. Cette méthode permet de caractériser les propriétés élastiques du matériau poreux dans une situation proche de son application réelleThis work was carried out in the framework of the project EcOBEx, whose main objective was to reduce the passby noise by mean of acoustic shields in the engine compartment of the vehicle. The acoustic shields are manufactured by thermocompression of uniform porous materials. The material’s properties and thickness evolve according to the degree of compression experienced by the material. The objective of this work is to propose some laws to predict the evolution of the materials properties from their initial non compressed values and the compression rate. Firstly, we focus on the parameters of the Johnson-Champoux-Allard-Lafarge (JCAL) equivalent fluid model : porosity, air-flow resistivity, tortuosity, viscous characteristic lengths, thermal characteristic length, static thermal permeability. Some analytical expressions are proposed to predict the variation of these parameters as a function of compression. They are derived from a physical model of cylindrical fibres where the fibre orientation variations induced by the thermocompression can be taken into account. The results are in good agreement with the measurements made two types of materials (open cell foam and fibrous). A generalized empirical model is finally proposed for the air-flow resistivity.In a second part, we focus on the elastic parameters, which are necessary to take into account the vibration of the skeleton. The quasi-static experimental method is first applied to study the evolution of the Young’s modulus along the compression rate for fibrous and open cell foams. A power law is then proposed to predict these variations. Finally, an inverse method for estimating the elastic properties of an orthotropic poro-elastic material from a vibratory measurement of a thermocompressed three layer sandwich structure is proposed. This method allows us to characterize the elastic properties of a porous material in a situation close to its actual application
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Burneika, Benas, Živilė Janulytė, and Živilė Janulytė. "Bešvaistiklio stūmoklinio mechanizmo tyrimai." Master's thesis, Lithuanian Academic Libraries Network (LABT), 2011. http://vddb.laba.lt/obj/LT-eLABa-0001:E.02~2011~D_20110610_160521-46223.
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Baigiamajame magistro darbe yra pateikti bešvaistiklio eksperimentinio kompresoriaus triukšmo lygio, vibracinio aktyvumo, elektros energijos sąnaudų, našumo tyrimų rezultatai. Tyrimams atlikti buvo suprojektuotas ir sukonstruotas specialus tyrimų stendas bei sudarytos tyrimų metodikos, parinkta tyrimų įranga. Eksperimentai buvo atliekami, esant skirtingiems kompresoriaus sukimosi greičiams ir keičiant slėgį, suspausto oro sistemoje. Triukšmo tyrimai buvo atlikti keliuose skirtinguose matavimo taškuose, vibracinis aktyvumas matuojamas keliomis skirtingomis koordinačių ašių kryptimis. Darbą sudaro 7 dalys: įvadas, mokslinės literatūros, susijusios su tiriamuoju objektu, apžvalga, tiriamos problemos analizė ir pagrindimas, teorinis pagrindimas, eksperimentiniai tyrimai ir jų rezultatų įvertinimas, lyginamoji analizė, išvados ir pasiūlymai, literatūra. Darbo apimtis – 132 puslapiai teksto be priedų, 139 iliustracijų, 34 lentelės, 37 bibliografiniai šaltiniai. Atskirai pridedami darbo priedai.The data of noise level, vibration activity, used electric power, duty research of crank less mechanism are submitted in the final thesis for the master’s degree. For research making was designed and constructed a special test stand, and scheduled research methodology. Experiments were carried out at different speeds of compressors and compressed air system pressure. Noise tests were carried out at several different points of measurement, vibration activity - a number of different coordinate axes. Structure: introduction, review of scientific literature related to the investigating object, analysis and justification of the investigated problem, theoretical justification, experiments and their evaluation of the results, comparative analysis, conclusions and suggestions, references. Thesis consists of: 132 pages text without appendixes, 139 pictures, 34 tables, 37 bibliographical entries. Appendixes included.
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Yeung, Chung Chuen. "Étude du cycle de compression d'un compresseur à piston." Compiègne, 1985. http://www.theses.fr/1985COMPI204.
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Payer, Florent. "Prédiction et analyse du phénomène de réponse forcée : application à un cas de compresseur haute pression." Phd thesis, Ecole Centrale de Lyon, 2013. http://tel.archives-ouvertes.fr/tel-01063776.
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L'enjeu de cette thèse est d'améliorer la compréhension et la prédiction du phénomène de réponse forcée des aubages de turbomachines en situation de résonance. L'étude a été menée au moyen de simulations numériques U-RANS 3D et en s'appuyant sur le compresseur d'essai ERECA, dédié au phénomène de réponse forcée. Pour prédire les amplitudes de vibration des aubages excités aérodynamiquement, la méthode de prédiction la plus répandue consiste à effectuer séparément un calcul d'excitation et un calcul d'amortissement aérodynamique ; on parle alors de calcul découplé. C'est cette méthode qui a été mise en œuvre dans un premier temps. Les calculs d'excitation et d'amortissement aérodynamiques ont été comparés individuellement aux résultats d'essais. Pour cela une méthode de traitement du signal fréquence/amplitude a été développée dans le but d'extraire l'amortissement et l'excitation des résultats d'essais. Les analyses des simulations ont permis de mieux comprendre les mécanismes d'excitation et d'amortissement aérodynamique. On a ainsi pu montrer que le phénomène d'interaction rotor/stator s'apparente par son caractère discontinu à une percussion périodique. Quant au phénomène d'amortissement, il se caractérise par le bilan des contributions de chaque zone d'échange d'énergie sur la paroi de l'aubage. En outre, les amplitudes vibratoires calculées à partir de cette méthode sont très proches des valeurs d'essais. Toutefois, cette procédure de calcul requiert la mise en œuvre de 2 calculs instationnaires différents et ne permet pas à l'heure actuelle d'être utilisée dans un cycle de conception. Dans le but de simplifier et d'améliorer la qualité de prédiction des analyses de réponse forcée, la méthode du couplage dynamique a été mise en œuvre et évaluée. Avec cette méthode, l'aubage répond librement aux sollicitations engendrées par le fluide. Une fois le régime transitoire évacué, l'aubage oscille en régime permanent. Cette méthode permet donc de prédire une amplitude vibratoire à partir d'un seul calcul instationnaire. En revanche, le calcul s'avère bien plus onéreux que la méthode découplée de par l'existence du régime transitoire. Dans le but de rendre accessible cette méthode à un niveau industriel, deux méthodes d'accélération du calcul ont été mises en place. Les résultats obtenus sont très encourageants et devraient permettre de réduire drastiquement les temps de restitution des analyses de réponse forcée. A la connaissance de l'auteur, cette thèse constitue une étude inédite de comparaison entre méthode découplée et couplage dynamique, qui par ailleurs s'appuie sur des résultats d'essais dédiés exclusivement au phénomène de réponse forcée.
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Defoy, Benjamin. "Investigation on the control of supercritical centrifugal compressors supported by active magnetic bearings : Toward a new control strategy?" Thesis, Lyon, INSA, 2012. http://www.theses.fr/2012ISAL0140/document.
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Le comportement dynamique des turbomachines industrielles doit respecter des critères émis par les normes internationales et les utilisateurs. Les rotors flexibles sont sensibles à la distribution de balourd, et sont soumis aux excitations aérodynamiques de leur environnement. Usuellement, les contrôleurs utilisés peinent à délivrer le niveau d’exigence demandé, par conséquent les propriétés mécaniques des paliers magnétiques sont fortement dépendantes de celles des rotors. L’objectif de ce mémoire est d’analyser le comportement dynamique des compresseurs centrifuges afin de proposer une stratégie de contrôle innovante. D’abord, chaque palier est considéré comme une entité a part entière en couplant ses deux axes d’action. Le comportement dynamique du rotor est exprimé dans le repère polaire. Par ailleurs, la logique floue, qui utilise un modèle de pensée proche du raisonnement humain, applique des actions correctives en fonction du comportement dynamique global du rotor. Ainsi, l’utilisation couplée de ces deux approches créé une synergie permettant d’agir sur le système de manière ciblée. Le contrôleur dissipe l’énergie cinétique du rotor lors du franchissement de vitesses critiques afin d’atténuer la réponse au balourd, ou augmente la raideur du palier lors de vibrations transitoires ou asynchrones afin de réduire la trajectoire du rotor. Le faible amortissement structurel du rotor le rend sensible au phénomène de « spillover » (l’énergie de contrôle affecte les modes de fréquence élevée). Or, la logique floue ne peut pas gérer ce phénomène. Ainsi, un contrôleur PID sous-jacent est utilisé pour maîtriser la stabilité des modes hautes fréquences. Au final, le contrôleur flou polaire permet d’obtenir des marges de performances entre les capacités de cet asservissement et le cahier des charges. Ces marges sont utilisées pour trois objectifs : le respect des spécifications, l’amélioration du comportement subsynchrone, et enfin la simplification et la standardisation du contrôleur sous-jacent nommé ici SPID. Ce contrôleur est tel que ses caractéristiques, dans la plage de fréquence utile, sont indépendantes du rotor pour une application donnée. Enfin, la stratégie développée est évaluée avec des simulations numériques et des essais expérimentaux. D’abord, le modèle numérique est validé, puis le contrôleur est appliqué à un banc d’essais académique. Le comportement est stable et robuste. Il présente des performances supérieures au PID augmenté fourni avec le banc, que ce soit pour la réponse au balourd, ou pour la réponse à des excitations subsynchrones. Finalement, la démarche est appliquée à un compresseur industriel. Les simulations montrent que le comportement est proche de celui exigé pour des machines sur paliers classiques. L’optimisation de l’approche et l’automatisation de la conception pourraient conduire à la standardisation des paliers magnétiques actifsThe dynamic behaviour of large turbomachinery should satisfy stringent requirements dictated by international standards and final users. Their flexible rotor is sensitive to the unbalance distribution and subjected to particular excitations coming from the industrial process. Usually, the performance margins between the requirements and the classical controller capabilities are small. Consequently, the magnetic bearing characteristics depend on the rotor geometry. Designing such controllers is difficult and time consuming. The objective of this thesis is to investigate the dynamic behaviour of supercritical centrifugal compressors in order to propose a new control strategy. First, each bearing is considered as one entity by coupling its two axes of action. The introduction of polar quantities permits a better observation of the rotor dynamic behaviour. In addition, by using logic close to human being reasoning, the fuzzy logic modulates the action forces as a function of the global dynamic behaviour. The coupling of the two approaches is an efficient way to apply targeted corrective actions. This controller attenuates the unbalance vibration when crossing critical speeds by applying damping forces, or increases the stiffness during transient or asynchronous excitations in order to limit the maximum displacement reached. As their structural damping is low, flexible rotors are very sensitive to spillover effect, which cannot be managed by fuzzy controllers. Consequently, an underlying PID is necessary. This hand-synthesized controller has high frequency characteristics tuned in order to ensure stability and robustness for each rotor. Compared to a classical approach, the polar fuzzy controller enables to increase the performance margins. These margins are used to fulfil three objectives: the achievement of standards requirements, the improvement of the subsynchronous behaviour, and the simplification and the standardization of the PID controller that we called SPID. This SPID is designed for a given application, such that the bearing characteristics on the operating frequency range are always the same. The control strategy is assessed numerically and experimentally. First, the numerical model is validated with experimental tests. Then, the controller developed is applied to an academic test rig. The controller is stable and robust. It exhibits performance superior to the augmented PID supplied with the test rig for both unbalance response and response to subsynchronous excitations. Finally, the control of an industrial compressor is assessed numerically. The results obtained are close to the standards requirements used for classical bearings. The optimization of the approach and the utilization of an automatic tuning algorithm for high frequency characteristics could lead to the standardization of Active Magnetic Bearings
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Khouz, Boujemaa. "Etude de la réduction de l'usure dans un lubrifiant contaminé par des particules." Ecully, Ecole centrale de Lyon, 1987. http://www.theses.fr/1987ECDL0004.
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Courtois, Sébastien. "Etude numérique et expérimentale du comportement vibroacoustique des clapets de compresseur frigorifique." Compiègne, 2003. http://www.theses.fr/2003COMP1447.
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Le compresseur à' piston, malgré sa conception ancienne, reste encore l'une des technologies de compresseur les plus utilisées. Il est présent entre autre dans les machines frigorifiques domestiques. Au cœur de la boucle frigorifique, il est la seule partie mécaniquement active du système et est donc à l'origine des principales nuisances sonores et vibratoires. D'admission ou de refoulement, le clapet est une pièce maîtresse. En effet, sa présence et son action conditionnent le comportement global du compresseur. Ce travail de thèse se propose d'étudier la dynamique de ces pièces pendant le cycle de compression en tenant compte des principaux phénomènes physiques présents dans leur environnement proche. L'objectif, in fine, est la conception d'un outil de prédimensionnement intégrant les besoins industriels. Aussi, un modèle numérique s'appuyant sur plusieurs domaines de la physique a été développé: thermodynamique, mécanique mais aussi tribologie. Une fois mis en place sur le plan informatique, plusieurs paramètres du modèle sont recalés par le biais de montages s' appu yant notamment sur la vélocimétrie laser et la profilométrie. Dans le but de diminuer le temps de calcul, plusieurs artifices sont utilisés, entre autre une décomposition et une troncature modales. L'utilisation d'une telle méthode dans un cadre non linéaire (contact) est justifiée pour cette application. Les résultats numériques sont par la suite confrontés à des mesures effectuées sur un compresseur instrumenté en fonctionnement réel.
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Beauvais, Romain. "Effets non linéaires acoustiques et couplages fluide-structure dans les guides d’ondes : application à des conduites de compresseurs alternatifs." Thesis, Le Mans, 2019. http://www.theses.fr/2019LEMA1015.
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Dans les industries de production pétrolière, chimique et gazière, les procédés de fabrication induisent l'utilisation de tuyauteries soumises à des gaz à hautes pression et température. Le transport du gaz est assuré par des compresseurs alternatifs raccordés à ces tuyauteries, dont le fonctionnement normal engendre la propagation d'ondes acoustiques menant à des vibrations de structures par couplage entre la colonne de gaz et la tuyauterie. Comprendre l'établissement et maîtriser le niveau de ces vibrations est un enjeu dimensionnant en raison de leur impact sur la sécurité des installations. Or, l'augmentation des vitesses de rotation des gammes de compresseurs, a accentué la génération de phénomènes acoustiques non linéaires. Ces phénomènes peuvent apparaître de manière générale au cours de la propagation pour des tuyauteries de grandes longueurs ou de manière locale au niveau des changements de section. Une modélisation numérique monodimensionnelle de la propagation non linéaire dans un réseau de tuyauterie est développée dans le domaine temporel et s'appuie sur le choix d'un modèle numérique par méthode FDTD. Parallèlement, une étude est menée concernant le couplage vibroacoustique entre le fluide et une tuyauterie coudée. La propagation d'ondes acoustiques engendre l'apparition de forces localisées au niveau des coudes. Le non-équilibrage de ces forces engendre des vibrations. La mesure des caractéristiques modales (déformées, fréquences et amortissement) est réalisée au moyen de tests vibratoires en des points stratégiques. Une méthode inverse est ensuite proposée afin de connaît le champ de pression interne à partir de mesures non intrusives d'accélérationIn the oil, chemical and gas industries, the manufacturing processes induce the use of pipelines subjected to gases at high pressure and temperature. The gas is transported by reciprocating compressors connected to these pipelines, whose normal operation generates the propagation of acoustic waves causing structural vibrations by coupling between the gas column and the piping system. Understanding the behavior and controlling the level of these vibrations is a major challenge because of their impact on the safety of the installations. However, the increase in the rotational speeds of new compressors has accentuated the generation of non-linear acoustic phenomena that can occur locally at section discontinuities (orifice, expansiona areas) or along the propagation in long pipes. A one-dimensional numerical model of non-linear propagation in a pipe network with cross-section discontinuities is developed in the time domain. This model is based on the choice of a FDTD (Finite Difference Time Domain) scheme adapted to weakly non-linear propagation with viscothermic losses in wave guides.In the meantime, a study is carried out on the vibroacoustic coupling between the fluid and a bent pipe. The propagation of plane acoustical waves generates the appearance of localized forces at the bends of a pipe. Vibrations are then induced by the unbalancing of these forces. The measurement of modal parameters (mode shapes, frequency and damping) is carried out by means of vibration tests at strategic points on the pipe. Then an inverse method is proposed in order to estimate the internal pressure field, based on non-intrusive acceleration measurements
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Baïz, Sarah. "Etude expérimentale du contact aube/abradable : contribution à la caractérisation mécanique des matériaux abradables et de leur interaction dynamique sur banc rotatif avec une aube." Phd thesis, Ecole Centrale de Lille, 2011. http://tel.archives-ouvertes.fr/tel-00605091.
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L'utilisation de revêtements abradables pour assurer l'étanchéité dynamique des turboréacteurs est une solution répandue qui permet d'augmenter la fiabilité et le rendement aérodynamique des turboréacteurs. En fonctionnement, des touches inévitables entre le revêtement et le bout d'aubes de rotor peuvent être à l'origine d'une usure excessive du revêtement abradable et/ou de la rupture d'aube. La simulation numérique de tels incidents butte sur un manque de connaissance des interactions aube/carter et des forces mises en jeu au contact, forces qui résultent notamment de couplages entre le frottement, l'usure du revêtement et des phénomènes vibratoires.Cette thèse a pour objectif de mieux appréhender les mécanismes d'interaction entre l'aube et le revêtement abradable. Elle résulte d'une collaboration entre l'ONERA de Lille et le Laboratoire de Mécanique de Lille et concerne le revêtement de type Al-Si/hbN (Metco 320NS), couramment utilisé dans les compresseurs à basse pression.Les propriétés physico-chimiques et le comportement mécanique - notamment en dynamique - du revêtement abradable sont étudiés. Compte-tenu d'une asymétrie du comportement en traction et en compression, l'exploitation en corrélation d'images numériques d'un essai original inspiré de l'essai Brésilien permet de rendre compte des mécanismes de dégradation. Le comportement tribologique est étudié sur tribomètre dans différentes configurations de contact. L'interaction entre l'aube et le revêtement ainsi que les couplages avec les vibrations d'aube sont investigués et caractérisés dans une configuration simplifiée et fortement instrumentée, sur un banc rotatif spécifique développé à l'ONERA de Lille
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Trkal, Tomáš. "Softwarový multiefekt pro postprodukci populární hudby." Master's thesis, Vysoké učení technické v Brně. Fakulta informačních technologií, 2017. http://www.nusl.cz/ntk/nusl-363784.
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This diploma thesis deals with design and implementation of complex software system for post-production of popular music. The system was implemented as a plug-in module in C++ language using JUCE application framework. The emphasis was on creating a well arranged and intuitive graphic user interface. The plug-in provides a set of audio effects and processors that can be connected into the desired graph structure. For less experienced users, there is a database of preset configurations usable for a variety of input signals.
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Wu, Jui-Te, and 吳瑞德. "Vibration Analysis for the Crankshaft in Scroll Compressors." Thesis, 1997. http://ndltd.ncl.edu.tw/handle/61599207240620371466.
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碩士國立交通大學
機械工程研究所
85
The scroll compressor is promising in the compressor industry due to its high efficiency, low vibration, low noise, few numbers of components, and high reliability. This work aims to investigate dynamics of the crankshaft that drives the scroll in a scroll compressor. Theoretical derivation and computer simulation are undertaken to provide a design basis for the design of scroll compressors, such as geometric design and strength analysis. The dynamic stiffness method is used to analyze the dynamic behavior of crankshafts. First, according to the governing equation of the beam, shape functions and dynamic stiffness matrices are obtained. The dynamic stiffness matrices for elements are combined to form the dynamic stiffness matrix of the entire system. The modal analysis method and the bisection method is employed to solve natural frequencies and mode shapes. The mode-superposition method and the Runge-Kutta method is in turn used to solve the dynamic response of the crankshaft. Finally, Experiments are conducted to measure shaking moments and forces of the crankshaft, which is driven by an AC servo motor.
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Wu, Hsien-Chang, and 吳憲璋. "Vibration Monitoring and Fault Diagnosis for Valves of Reciprocating Compressors." Thesis, 2002. http://ndltd.ncl.edu.tw/handle/58432556436940044743.
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碩士國立海洋大學
機械與輪機工程學系
90
To avoid unexpected down time or fault of equipment and to improve the quality of working environment, it is necessary to establish a fault detection and diagnosis system. Valve damage is a common fault in reciprocating compressors. An on line fault detection and diagnosis system will be developed in this study for valves of a reciprocating compressor which is in service. The traditional Fourier transform can not provide sufficient information for decision making due to the time-varying and non-stationary characteristics of the valve vibration signals of the reciprocating compressors. Time-frequency analysis technique is then crucial for successful treatment. The short time Fourier transform belongs to the class of linear time-frequency analysis and is subject to the constraint of uncertainty principle. Therefore, its time-frequency analysis resolution is quite limited. On the other hand, when applying the quadratic time-frequency distribution function for analysis of vibration signals, it is necessary to consider the effects of disturbances. The selection of an appropriate kernel to serve as a filter is crucial for removing the disturbances. This study applies the reassigned smooth pseudo Wigner-Ville distribution function as an analysis tool. The probabilistic neural network is applied to classify and signal class, which completes the establishment of the fault detection and diagnosis system.
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Lin, Feng-Hao, and 林豊皓. "Vibration Reduction of Reciprocating Compressors byUsing Taguchi’s Parameter Design Methods." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/37329984175134539111.
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碩士大同大學
機械工程學系(所)
94
ABSTRACT This article mainly describes the vibration characteristic for the reciprocating compressor and to find out the best parameter to decrease its vibration. In the known parameter of reciprocating compressor geometry size, operating condition, the MATLAB software with the computer value method was adopted to analyze the reciprocating and rotating inertial force on mechanism such as piston and rod in the reciprocating compressor. The affiliation by the MATLAB software may easily change the related parameter of reciprocating compressor to carry on the computation. On the basis of obtained inertial force to estimate balancing mass. After that Taguchi’s parameter design methods was adopted to carry out the control factor analysis, on reciprocating compressor characteristic to optimize the design parameter with the help of computer to speed up the product development and performance improvement.
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Chiu, Chao-ching, and 邱朝慶. "Vibration Analysis of Twin Screw Compressor." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/58333734464610442434.
Full textAbstract:
碩士國立中正大學
機械工程所
96
The thesis focuses on the vibration analysis of twin-screw compressors by using finite element software ANSYS. In the first part, the natural frequency and mode shapes of female and male rotors are investigated individually using ANSYS and the results are validated experimentally by modal testing. The deviations in natural frequency between ANSYS and experiment up to the first six modes all are within 7%. Moreover, results from ANSYS reveal that a torsional mode corresponding to 880 Hz while two rotors is meshing together is much lower than those of the individual modes of female and male rotors, respectively. It implies that this torsional mode plays an important role in the vibration of twin screw compressor. The second part of the thesis studies the vibration response for a twin screw compressor while the varying pressure is taken into consideration in the FEM model. The air pressure is obtained experimentally and then is transferred to the FEM model. Therefore the vibration response of the twin screw compressor is determined semi-empirically. A user-friendly interface is developed to conduct the vibration analysis of twin screw rotor with air pressure included automatically. By simply input the data of rotor profile and the contact line between two rotors, one may utilize this program integrated with ANSYS to determine the mode shapes, bearing forces, and stress distribution of a twin screw rotor.
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黃惟邦. "Vibration Analysis of Twin Screw Compressor." Thesis, 2004. http://ndltd.ncl.edu.tw/handle/85237899129928204640.
Full textAbstract:
碩士國立中正大學
機械系
92
The moving compressed air is one of main sources, which causes the vibration of the twin screw compressors. However the compressed air is also influenced by the mesh between the rotating male and female rotors. In this thesis, the rotors in a twin screw compressor are modeled as two simply supported Timshenko shaft due to the fact that both the male and female rotors are stubby. The displacement responses for both the male and female rotors are represented using assumed mode method and then the equation of motion is derived using the Lagrange method. The dy-namic characteristics that include natural frequencies and the mode shapes are obtained by solving the free vibration of the system. The tran-sient response is also obtained by using the Runge-Kutta method. The displacement responses corresponding to two different tooth profiles are studied. Results show that the tooth file affects the compressed air and thus it influences the associate vibration response of the meshing rotor. The algorithm developed in this thesis provides a tool which predicates the vibration response of the twin screw compressor after the tooth profile of the rotor is determined.
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TSENG, JI-FU, and 曾季甫. "Vibration and Strength Analyses of Heavy Industrial Compressor." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/98ab5e.
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碩士明志科技大學
機械工程系機械與機電工程碩士班
107
This paper focuses on the following analysis of large compressor structures: First, the compressor drives the crankshaft structure via the motor system as a rotating mechanism. Vibration occurs when rotating, and modal analysis is required to know the natural frequency of the structure. And determine whether the structure meets the standards through the guidelines presented in this paper. Through the model of the guidelines presented in this paper, screening will be conducted to find the best structure. For stress analysis. Secondly, stress analysis is used to observe the stress distribution of the structure to judge whether the structure is damaged; and relevant improvement methods are proposed to avoid damage to the structural system of the compressor. Third, the assessment of fatigue life can be measured if the system is lower than the strength of the fall; it means that it is safe, and the system is "not" capable of withstanding long-term operation. Therefore, it is necessary to know whether the working cycle of the system is infinite life. This article also adds to the discussion of the inaccuracy of the heart to initially establish an evaluation method; through the finite element analysis software, the relevant results required above can be obtained. This study is based on CAD/CAE integration and is the basis for entering the analytical field.
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Bing, Su I., and 蘇怡賓. "DIAGNOSIS AND IMPROVEMENT OF VIBRATION AND NOISE ON SCROLL COMPRESSOR." Thesis, 2000. http://ndltd.ncl.edu.tw/handle/49573132704292735148.
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碩士國立交通大學
機械工程系
88
Compressors are critical components of air conditioning systems. In particular, scroll compressors have the advantages of high efficiency, reliability and low vibration and noise level, as compared with conventional compressors. This research is focused on the diagnosis of vibration and noise in scroll compressors. The tools for diagnosis employed in the paper comprise spectral and cepstral analysis, radiation analysis, modal analysis with eigensystem realization algorithm (ERA), and operation deflection shapes (ODS). From the results of diagnosis, it is concluded that the major sources of vibration in the mechanical part are looseness of components, misalignment of rotor, structural resonance, and the weak supports of stator, while the source in flow part is cavitation. To reduce the noise and vibration identified in aforementioned diagnosis, the following solutions are proposed in the thesis. Rib design is proposed to reinforce the structure of compressor surface to restrain the transformation of noise. Silencer design is proposed for the check valve to reduce flow noise.
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余宗慶. "The Research for the Vibration of the Sliding-Vanes Rotary Compressor." Thesis, 2000. http://ndltd.ncl.edu.tw/handle/54920939404178367361.
Full textAbstract:
碩士國立臺灣大學
機械工程學研究所
88
The vibration problems of sliding-vanes rotary compressor mainly have two types : (1) the vibration of impact between the vanes and the bore of the stator, and (2) the vibration of slapping impact between the vanes and the slots of the rotor. In order to improve and reduce the vibration problems, to decrease the induced noises, to increase the life of the compressor and its vanes, and to improve the operational performance and efficiency , this thesis is deeply devoted to research and disscussions for the major vibration problems of the compressor.
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Chan, Po-Hao, and 陳柏儫. "Noise and Vibration Study on Rotary Compressor and Air Conditioner System." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/76700302367869021325.
Full textAbstract:
碩士國立屏東科技大學
機械工程系所
103
The rotary compressor is one of the key components and the major source of noise and vibration in air conditioners. The compressor assembly to the air conditioner may incur unwanted noise and vibration that is of concern for manufacturers. The identification of noise and vibration of the air conditioner system related to the compressor is crucial particularly for compressor manufacturers to improve their compressor design. This thesis first illustrates the working principle of air conditioner system and introduces how to precede noise and vibration measurement as well as the evaluation method. In measurement and evaluation of noise and vibration, two types of tests, including the receiver test (R-Test) and path test (P-Test), are presented. The R-Test is to investigate the noise characteristics of the rotary compressor in different operating conditions, and so forth the correlation study between noise and vibration is also studied. Then, the R-Test for the air conditioner is performed to examine the noise conditions as well as the correlation study between noise and vibration. Finally, the comparison of noise and vibration between the rotary compressor and the air conditioner system is explored. From the P-Test on the compressor with the knowledge of modal properties, the noise diagnosis on the rotary compressor can be carried out, and the noise diagnosis procedure can also be established for practical application. Results show the rotary compressor in operating reveals significant noise bands at 250, 800 and 1250Hz. When the compressor assembled into the air conditioner, the noise level is reduced 13.08dBA, and the noise insulation layer can reduce 2.43dBA. Also, the 250 and 400Hz of 1/3 octave band become the major contribution that should be considered in noise diagnosis and improvement for the compressor. This work aims to investigate the correlation of noise and vibration between the rotary compressor and air conditioner and develop the diagnosis procedure for compressor noise improvement. The experimental approach and diagnosis procedures can be useful for compressor manufacturers to improve the compressor design in particular for noise and vibration concerns.
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Wang, Wen-Chih, and 王文志. "Measurement and Evaluation of Sound and Vibration for Twin Screw Compressor." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/75436079441678909683.
Full textAbstract:
碩士國立屏東科技大學
機械工程系所
101
Noise emission from twin screw compressors is of concern in industry. The establishment of noise and vibration measurement and evaluation procedures is important and beneficial to increase the efficiency of development as well as quality control. To build up a standard operation procedure for measurement and evaluation on noise and vibration is the main theme of this work. This thesis first describes the idea for noise and vibration measurement and develops the receiver test and path test for detail experimental implementation. The receiver test aims to discuss the noise of compressor in different operating conditions as well as the correlation analysis between noise and vibration of compressors. Experimental approaches in the receiver test are accordingly planned. The noise characteristics for different types of twin screw compressors are then presented. The procedure for the path test is also established and conducted to evaluate and diagnosis the possible noise sources. The sound power level of a twin screw compressor is finally determined by referring to ISO standards to build up the measurement and analysis procedures. This work lays out the noise and vibration measurement as well evaluation procedure in particular for the twin screw compressor and leads to provide an objective way to conduct the noise diagnosis for machineries.
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Chung, Chih-Linag, and 鍾志良. "Inverter Application for Temperature Precision and Compressor Vibration Improvement on Machine Tools Cooling System." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/79996251859660952829.
Full textAbstract:
碩士國立勤益科技大學
電機工程系
101
An inverter-based compressor cooling system with high temperature precision and high efficiency for machine tools is presented in this thesis. The cooling capability of inverter compressor is better than conventional ones at different frequencies. The closed-loop auto-tuning system is designed based on detection the temperature of the outlet water, and the temperature accuracy is maintained ±0.1℃ for different conditions—low, medium, and full loads. The vibration of the compressor can be reduced by using speed sensorless vector-controlled skill, and that is superior to V/f one. All the control programs are developed by Infineon micro-processor MCU XE164FM-72F80L.
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Lee, Yang-Ruei, and 李泱叡. "Modeling of Vibration Prediction of a Rotary Compressor with Cyclic Gas-induced Loads Based on Multi-body Dynamics." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/q87ad8.
Full textAbstract:
碩士國立中央大學
機械工程學系
106
With its simplicity and low cost, rotary compressors are widely adopted in household air conditionings. The geometric structure of the compressor is asymmetrical to form an eccentric cam in order to conduct the compression process of the refrigerant. However, eccentric rotation cause huge dynamic unbalance, which is one of the major vibration sources of rotary compressors. Additionally, cyclic gas-induced loads in compression chamber and unstable motor torque input also are vibration sources of rotary compressors. By establishing a multi-body dynamic model considering dynamic balance of rotor system, cyclic gas-induced loads, variation of motor speed, characteristics of rubber grommet, suction tube and discharge tube to predict the vibration response of rotary compressor. Doing experiments to verify multi-body dynamic model, which is reliable then doing a series of simulations and analysis about effects of balancers on vibration reducing. There are two conclusions, the matches of main balancers and top balancers are more effective on vibration reducing than the tolerances of balancer weights. Gas-induced loads also affect the effects of balancers, therefore it is better to consider gas-induced loads when design balancers.
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Hsu, Po-Hua, and 許博華. "Prediction of Dynamic Responses and Vibration Spectrum Characteristics for a Twin-screw Compressor under Different Gas-induced Loads." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/99137697954330647078.
Full textAbstract:
碩士國立中央大學
機械工程學系
104
A Study of the Correlation between Geometric and Dynamic Properties of Twin Screw Compressor Rotors under Circulating Pressure Load. High performance and low noise are characteristics of twin screw compressors, and they are often used in many industries that require energy saving and high efficiency energy systems. Establishing a model that can successfully predict the dynamic responses of twin screw compressors under circulating pressure loads can improve the system’s rotational properties, and easily change various working components such as rotor screws, bearing components, gaining preliminary understanding of changes in rotational speed, rotation frequency, tooth load, and vibration signal in female rotors., substantial design parameters for the industry can then be provided. Therefore, this study proposes a new method to establish a multibody dynamics model for rotor screws and bearing systems. Variations in axial force, radial force and moment of force of circulating pressure on rotor screws within the compressor’s working chamber are investigated, Hertz contact stiffness of varying rotor contact on radius of curvature is also examined. Multibody dynamic responses of rotor screws and bearing systems within the oil-injected twin screw compressor are then examined through theory and examination. This study then uses the established multibody dynamics model to examine the internal working chamber’s nine dynamic properties, including excessive compression, vibration, half load, rotor axial deviation, and heat and pressure effects. These property changes are organized and concluded to inspect the effects on the female rotor’s rotational frequency output, tooth load, vibration signal frequency spectrum. The conclusions are provided as substantial suggestions for manufacturers to preliminarily investigate compressor noise source, and improving the dynamic properties of compressors.
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Subramanya, S. "Prediction of Physical Behavior of Rotating Blades under Tip-Rub Impact using Numerical Modeling." Thesis, 2013. http://hdl.handle.net/2005/3083.
Full textAbstract:
Rotating blades, which are the most critical components of any turbo-machinery, need to be designed to withstand forced vibrations due to accidental tip rub impact against inner surface of casing. These vibrations are typically dependent on operating conditions and geometric parameters. In the current study, a rotor test rig with a maximum tip speed capability of 144 km/hr has been developed for studying the dynamic behavior of representative jet engine compressor blades actuated by the closure of clearance between the tip of a given rotating blade and a sector of the inner lining of the casing. Ten different blade profiles are chosen in the present research. The blades are obtained by lofting NACA GOE123 airfoil cross-section along different stacking axes.
Rotor test rigs which simulate transient dynamic events require high frequency data acquisition systems like slip ring arrangement or telemetric transmission. While slip rings introduce noise into the signal, the telemetric transmission works out to be rather expensive. To circumvent the stated shortcomings of data acquisition systems, a novel rotor-mounted data acquisition system has been implemented here which captures dynamic strains in vibrating blades during operation. The current data acquisition system can store data for duration of five seconds with a sampling rate of 35 kHz. It has been calibrated with four standard tests, and provides a simple and efficient mode of data capturing. Three blades with airfoil sections (a flat beam-type blade of uniform rectangular cross-section, a blade with twisted cross-sections stacked along a straight line, and a blade similar to the latter but with a curved stacking axis) are tested under controlled rub conditions at four different speeds. The maximum test speed is restricted to 800 rpm for reasons of safety although the set-up is designed to operate up to a maximum speed of 2000 rpm. For each of the rotor speeds, a blade is tested for three to four different stagger angles in the range of 0o-30o. By plotting the RMS values of measured dynamic responses with respect to stagger angle for a given rotor speed, it has been observed, perhaps for the first time in published literature, that a stagger angle of around 20o yields the maximum RMS value of strain response.
A major objective of the current study has been to utilize the data generated in the tip rub impact tests for validating a predictive numerical model of the test set-up using explicit finite element analysis. To this end, a finite element model of the rotor rig inclusive of a rotor with two blades and the static frame structure is developed and analyzed using an explicit LS-DYNA solver. This model is calibrated with the test results of the three blade designs described above. In particular, it has been shown that the frequency contents of the measured dynamic strain responses agree quite well with frequencies obtained from the numerically computed responses. It has been found in the experimental responses that a given blade vibrates with two main frequencies: one corresponding to the first natural frequency of the rotor-blade system during the tip-rubbing phase (which lasts until the blade tip is in contact with the rub element which is a sector of the circular casing), and another corresponding to the first natural frequency of the blade when it vibrates freely without its tip being in contact with the rub-liner of the casing. A shortcoming of the current modeling approach is its inability to realistically represent the damping behaviors observed in the tests. For reasons of computational efficiency and consistent with the fact that there was no perceptible damage in the tested blades, an elastic constitutive behavior is specified for the blades, while the sacrificial PVC rub-liner is assumed to behave elasto-plastically. A limited study has also been carried out by assigning an elasto-plastic constitutive model to one of the blades previously represented with elastic properties only, and although incipient yielding is observed in a highly localized region at the tip of a blade (which can also be a numerical artifact), the responses under the two material behavior considerations (i.e. elastic and elasto-plastic) are found to be nearly same.
Finally, this validated modeling approach is applied to the study of blades of ten distinct geometric profiles (including the three configurations already considered) at a speed of 800 rpm and the resonant speed of a given blade. Comparisons are made between the relevant responses (such as time-histories of root strain, shaft torque, blade axial displacement, bearing load and rub force) of nine blades with airfoil cross-sections (leaving aside the results for the first blade of rectangular cross-section which is only of academic interest). Based on this study, of all the blade designs, it has been found that the curve-stacked airfoils exhibit better ‘Rub-tolerant’ behavior. Both experimental and simulation results have predominantly proven the fact that adding curvature to a straight stacked blade through curve-stacked or bow result in reducing the rub induced vibration. While sweep and bow provide some aerodynamic advantages, they are not much helpful in containing the vibrations to a sustainable extent.