Letteratura scientifica selezionata sul tema "Fans, Mechanical"
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Articoli di riviste sul tema "Fans, Mechanical"
1
Langston, Lee S. "Focus on Fans". Mechanical Engineering 132, n. 08 (1 agosto 2010): 51. http://dx.doi.org/10.1115/1.2010-aug-7.
Testo completoAbstract (sommario):
This article discusses ongoing research in the area of turbofans used in jet engines. P&W’s gear facilities in Middletown Connecticut have been developing the fan gearbox over a period of 20 years. The company has a long history of gearbox experience associated with their very popular turboprop gas turbines at Pratt & Whitney Canada. Field tests have shown that the geared turbofan has a much lower level of noise. Currently, some airlines have as much as 35–60% of their operating costs in jet fuel use. If the geared fan engine does indeed significantly reduce fuel use, this improvement in fan performance will be hard for the competition to beat. Another way to improve fan performance is to change the pitch of fan blades, during an aircraft flight cycle. Rotating Composite Technologies, a small firm in Kensington, Conn. has also come up with a unique patented design for the variable pitch fan that promises to overcome the deficiencies of those tested in the 1990s.
2
Brown, Alan S. "From Whales to Fans". Mechanical Engineering 133, n. 05 (1 maggio 2011): 24–29. http://dx.doi.org/10.1115/1.2011-may-1.
Testo completoAbstract (sommario):
This article discusses a story about a man named Fish who noticed something unusual about whale flippers and who, after nearly 30 years, turned it into a technology platform. This technology takes its inspiration from the natural design of the bumps, or tubercles, on humpback whale flippers. The 24-foot-diameter fans, based on tubercle technology, use half the number of blades and move 25% more air and consume 25% less power than fans with conventional blades turning at the same speed. After thousands of years of hiding in plain sight, tubercles are emerging as a real, if limited, technology platform. Research has shown tubercles work only on thick, tapered wings operating in a very narrow laminar-to-turbulent transition regime. Whale-inspired fans are already available, and wind and tidal power blades could be the next.
3
Chen, P., M. Soundra-Nayagam, A. N. Bolton e H. C. Simpson. "Unstable Flow in Centrifugal Fans". Journal of Fluids Engineering 118, n. 1 (1 marzo 1996): 128–33. http://dx.doi.org/10.1115/1.2817490.
Testo completoAbstract (sommario):
Rotating stall and the inlet vortex in centrifugal fans with inlet vane control has been studied. The advances in stall research in aero-engine compressors are discussed. The present study shows that stall in centrifugal fans can be quite different from that in axial compressors, in that stall can occur in a progressive and intermittent fashion. The study also shows that a discontinuity in the fan characteristic is not necessarily accompanied by rotating stall, unlike the axial machines. Experimental results indicate that the positive prewhirl created by inlet vanes tends to delay the occurrence of stall. Also, dorsal fin devices that are used to control the inlet vortex do not seem to affect the stall point unfavorably. The inlet vortex frequency was found to invariably exhibit a linear relation with the flow rate even when dorsal fins were used. This offers a practical method to distinguish between the inlet vortex and rotating stall.
4
Wright, T., e W. E. Simmons. "Blade Sweep for Low-Speed Axial Fans". Journal of Turbomachinery 112, n. 1 (1 gennaio 1990): 151–58. http://dx.doi.org/10.1115/1.2927413.
Testo completoAbstract (sommario):
The available literature on aerodynamic and acoustic properties of axial fans with swept blades is presented and discussed with particular emphasis on noise mechanisms and the influence of high-intensity inlet turbulence on “excess” noise. The acoustic theory of Kerschen and Envia for swept cascades is applied to the problem of axial fan design. These results are compared to available data and a provisional model for specifying sweep angles is presented. The aerodynamic performance theory for swept-bladed rotors of Smith and Yeh is adapted for use in designing low-speed axial fans. Three prototype fans were designed using the resultant computer codes. One is a baseline fan with blade stocking lines radially oriented, and two are fans having swept blades of increasingly greater forward sweep. Aerodynamic testing shows that performance of the fans lies within a band width of about ± 2 percent of volume flow rate and pressure rise predictions in the region of design performance, effectively validating the design procedure for selection of the blading parameters. Noise testing of the fans was carried out and the results show an average noise reduction for the swept-bladed fans of about 7 dBA overall, and a reduction of pure tone noise at blade-pass frequency of about 10 dB compared to the zero-sweep baseline model, in close agreement with the theory of Kerschen and Envia.
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V.S., Dmitriev, Kostyuchenko T.G., Minkov L.L., Derdiyashchenko V.V. e Panfilov D.S. "VIBROACTIVITY OF LOW-NOISE FANS". Vestnik Tomskogo gosudarstvennogo universiteta. Matematika i mekhanika, n. 68 (2020): 61–71. http://dx.doi.org/10.17223/19988621/68/6.
Testo completoAbstract (sommario):
Low-noise fans are widely used in the sphere of human life for sanitary and technological purposes. Creation of low-noise fans is currently an advanced scientific and technical area. In some fields of their application, reduced vibrations and noises are of paramount importance not only in terms of sanitation and health, but also from a scientific point of view. This work presents a comparison of the quality of low-noise fan development depending on the selected resistance type. The efficiency of the damping of mechanical system (a low-noise fan) vibrations according to the type of resistance moment used is confirmed analytically and practically. Nowadays, a number of fan types implemented in hundreds of designs have been developed and are in service. In this work, the whole variety of the produced nomenclature of low-noise fans is reduced to two basic types – axial and radial. The paper reports that to ensure minimum noise in the operating mode of the low-noise fans presented in the work, a wideband vibration damper is needed as a required functional unit, and the walls of the fan housing should be sandwich-like with layers made of sound absorbing, sound insulating, and vibration damping materials.
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Beiler, M. G., e T. H. Carolus. "Computation and Measurement of the Flow in Axial Flow Fans With Skewed Blades". Journal of Turbomachinery 121, n. 1 (1 gennaio 1999): 59–66. http://dx.doi.org/10.1115/1.2841234.
Testo completoAbstract (sommario):
A numerical analysis of the flow in axial flow fans with skewed blades has been conducted to study the three-dimensional flow phenomena pertaining to this type of blade shape. The particular fans have a low pressure rise and are designed without stator. Initial studies focused on blades skewed in the circumferential direction, followed by investigations of blades swept in the direction of the blade chord. A Navier–Stokes code was used to investigate the flow. The simulation results of several fans were validated experimentally. The three-dimensional velocity field was measured in the fixed frame of reference with a triple sensor hot-film probe. Total pressure distribution measurements were performed with a fast response total pressure probe. The results were analyzed, leading to a design method for fans with swept blades. Forward swept fans designed accordingly exhibited good aerodynamic performance. The sound power level, measured on an acoustic fan test facility, improved.
7
Zhao, Wenxuan, Wei Ye, Qianru Zhang e Xu Zhang. "Simulations on arrangements of induced jet-fans as auxiliary ventilation for a mechanical ventilated space with openings". E3S Web of Conferences 111 (2019): 01036. http://dx.doi.org/10.1051/e3sconf/201911101036.
Testo completoAbstract (sommario):
Underground garages, indoor stadiums, or more commonly used seagoing ships, can be used as large multi-purpose spaces, which are suitable for the carriage of a wide range of cargoes, as well as evacuation of people at overseas. The indoor environment in a multi-purpose cabin usually varies, in terms of pollutant emissions, hazardous levels and the corresponding ventilation requirements. A possible solution, in addition to a single regular HVAC system, is to use multiple induced jet fans. However, to pre-determine a universal design of fans, e.g., numbers, locations, directions, angles and flowrates, etc., may not be practical. In this preliminary work, methods to design the auxiliary ventilation system were discussed. The heat sources are located in the four corners on the floor. CFD method is used to further study the effects of six regular and four irregular arrangements of a 2×2 array of fans on local heat dilution with or without natural ventilation (e.g., additional openings in the space). Heat exhaust efficiency is used to evaluate the effects of different arrangements of fans on local heat dilution. The results show that adjustable ventilation using induced fans would be useful to provide various airflow distribution for a large space and the dilution of the heat can be improved and the areas of high temperature inside the space can be reduced. Furthermore, the heat exhaust efficiency would be higher and the induced fans have a more significant effect, especially when additional natural ventilation is available.
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Chun, Guo, Wang Mingnian e Tang Zhaozhi. "A Study on Surge and Stall under the Interaction of Parallel Axial flow fan in Tunnel". Noise & Vibration Worldwide 42, n. 11 (dicembre 2011): 9–14. http://dx.doi.org/10.1260/0957-4565.42.11.9.
Testo completoAbstract (sommario):
In the ventilation design for tunnels above 10km, an axial flow fan of great power needs to be set in ventilation shafts. There are few provisions on the setting modes and less discussion of parallel axial flow fan mode in the Specifications for Design of Ventilation and Lighting of Highway Tunnels. All of these bring a lot of difficulties about the axial fan selection, layout and control design. There is no specialized research on axial flow fan for tunnels and no studies on surge and stall under the interaction of parallel axial flow fan in tunnel in spite of the more and more application of parallel axial flow fan. So, this paper conducts a study on surge and stall under the interaction of parallel axial flow fan in tunnels. Through the study on the operating principle and analysis of parallel axial flow fan, we can know that the noise will increase suddenly, which will in turn result in fan vibration and running instability once the stall occurs. When a fan surges, the air volume and pressure, the motor current will fluctuate sharply, which brings significantly increased vibration and noise. At the same time, the rotary blade and the shell are subject to considerable stress effects and the fan will possibly suffer from great damage. The surge will occur in the unstable zone of axial fan performance curve. The strong pulsation and periodic oscillation of the air flow will increase the noise, which is a serious damage to the fan. So an axial fan should avoid this zone in running. With two axial flow fans of the same power parallel, the mutual influence is not very great. Therefore this research will focus on the efficiency in the case of two fans with a high and a low power parallel. Stall will occur if the outside pressure is greater than the outlet pressure. Once the stall happens, the noise will increase suddenly, which will in turn result in fan vibration and running instability. When two fans parallel, i.e. when the power ratio of the parallel fans is over 5.3, the possibility of the small fan's stall is high, otherwise it is small. With regard to the running efficiency of parallel axial flow fans and the starting safety, it is better to parallel two fans, and the fans with adjustable movable vanes or frequency control or the ordinary nonadjustable fans can be used.
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Bamberger, Konrad, e Thomas Carolus. "Efficiency limits of fans". Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy 234, n. 5 (27 settembre 2019): 739–48. http://dx.doi.org/10.1177/0957650919876838.
Testo completoAbstract (sommario):
The purpose of this work is to identify upper efficiency limits of industrial fans such as axial rotor-only fans, axial with guide vanes, centrifugal rotor-only and centrifugal with volute. The efficiency limit is always a function of the class, the design point within the class and the definition of efficiency (total-to-static and total-to-total). The characteristic Reynolds number is another relevant parameter. First, based on analytical and empirical loss models, a theoretical efficiency limit is estimated. A set of idealizing assumptions in the loss models yields efficiencies which are assumed to be an insuperable limit but may be unrealistically high. Second, more realistic efficiency limits are estimated using a computational fluid dynamics-based optimization scheme, seeking for the best designs and hence the maximum achievable efficiencies in all classes. Given the self-imposed constraints in the geometrical parameter space considered, the thus-obtained practical efficiency limits can only be exceeded by admitting more complex geometries of the fans.
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Suzuki, Yasuyoshi. "Replacement of Existing Fans with High-Efficiency Fans for Energy Saving." JAPAN TAPPI JOURNAL 53, n. 11 (1999): 1417–22. http://dx.doi.org/10.2524/jtappij.53.1417.
Testo completoTesi sul tema "Fans, Mechanical"
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Du, Toit Jacques H. (Jacques Hendrik). "An evaluation of a design method for mixed flow fans". Thesis, Stellenbosch : Stellenbosch University, 2002. http://hdl.handle.net/10019.1/52665.
Testo completoAbstract (sommario):
Thesis (MScEng)--University of Stellenbosch, 2002.ENGLISH ABSTRACT: Mixed flow fans find application in an operating region between that of axial flow and centrifugal fans. The candidate investigated the working of these mixed flow fans and formulated a design algorithm. The algorithm was based on work done by previous authors, most of which have tried to modify existing axial flow fan design methods to suit the mixed flow case. A fan was designed, built and tested. Tests showed that the fan did not perform as designed, producing a lower pressure rise at a lower flow rate. A five hole probe was used to measure the exit flow vector and the results showed that most of the work was done by the lower half of the blade. Based on this discrepancy between the designed and actual fan performance, a number of changes to the design procedure were recommended. Amongst other things: the use of numerical blade modelling procedures instead of modified cascade correlations and the disregard of the Coriolis work in the design of the blade shape.
AFRIKAANSE OPSOMMING: Gemengde vloei waaiers bevredig die behoefte aan 'n waaier in 'n spesifieke werksgebied waar aksiaal en sentrifugale waaiers minder effektief is. Die projek ondersoek die werking van gemengde vloei waaiers en formuleer 'n ontwerp-algoritme. Die algoritme is gebaseer op bestaande navorsing, waarvan die meeste 'n poging is om aksiaalvloeiwaaiermetodes aan te pas vir die gemengde vloei geval. 'n Waaier is ontwerp, gebou en getoets. Toetsresultate toon dat die waaier 'n laer drukstyging by 'n laer volume vloei gee as wat die ontwerp voorspel. 'n Vyfgat-anemometer is gebruik om die uitlaatvloei-vektor te meet en die resulate het bewys dat die gedeelte van die rotorlem naaste aan die naaf meeste van die werk doen. Hierdie afwyking van die ontwerptoestand is ondersoek en 'n aantal veranderings aan die ontwerp algoritme is voorgestel, naamlik: die gebruik van numeriese lemprofiel simulasie, instede van die glip- en deviasie- modelle, en die ontwerp van die lemprofiel deur die Coriolis werk te Ignoreer.
2
Augustyn, Ockert Philippus Hermanus. "Experimental and numerical analysis of axial flow fans". Thesis, Stellenbosch : Stellenbosch University, 2013. http://hdl.handle.net/10019.1/85720.
Testo completoAbstract (sommario):
Thesis (MScEng)--Stellenbosch University, 2013.ENGLISH ABSTRACT: The majority of power stations in South Africa are located in coal rich, but arid regions where wet-cooled condenser systems are not feasible from an environmental and economic perspective. Consequently the focus on power generation cooling has shifted towards dry-cooling systems using air-cooled steam condensers (ACSC). The steam passing through the ACSC units is cooled by an air-draught, mechanically induced by large diameter axial flow fans. Consequently the effectiveness of the cooling is impacted by the performance of these fans, which ultimately affects the overall efficiency of the power plant. However, due to the large diameters (> 10 m) of these fans, their performance is predicted based on small scale test results using the fan scaling laws. The objective of this project was to develop a methodology which accurately predicts the fan performance of more than one fan configuration using computational fluid dynamics (CFD) software and validating the results with experimental tests. Four fans were considered in this study of which three were scaled fan models of large air-cooled axial fans. The performance of the scaled fan models (L1-, L2- and N-fan) were measured in a type A, BS 848 standard fan test facility. The geometries of the fans were scanned three-dimensionally to obtain the models for simulation purposes. The other fan considered was an 8- bladed axial fan designed by Bruneau (1994) and referred to as the B-fan. Simulations were carried out for the L2-, N- and B-fan for different computational domains while implementing the multiple reference frames (MRF) and steady RANS approach. Three variations of the k-ε turbulence model were also investigated. Noticeable differences were found between the experimental and numerical results of the B-fan. Good correlations between the numerical and experimental fan static pressure, fan power and fan static efficiency were found for the two scaled model fans over a large operating range. The performance of the full scale fans, however, did not correlate well with the performance of the scaled models. It is concluded that accurate simulations of axial fans are possible although these domains require a large number of mesh elements. It is recommended that further research is carried out to investigate the relationship between full scale and small scale fan models.
AFRIKAANSE OPSOMMING: Die meerderheid steenkool kragstasies in Suid-Afrika is geleë in droë, maar steenkool ryke streke waar natverkoelde kondensor stelsels uit ʼn omgewings en ekonomiese perspektief nie geskik is nie. Die fokus in kragopwekking verkoeling het dus verskuif na droë-verkoelings stelsels en spesifiek die gebruik van lugverkoelde stoomkondensors (LVSKs). Die stoom in LVSK eenhede word verkoel deur atmosferiese lug wat meganies geïnduseer word deur groot aksiaalvloeiwaaiers. Die effektiwiteit van die verkoelingsproses word gevolglik beïnvloed deur die werksverrigting van hierdie waaiers wat uiteindelik die algehele effektiwiteit van die kragstasie beïnvloed. As gevolg van hierdie waaiers se grootte word hulle werksverrigting egter bepaal op grond van kleinskaal toetsresultate en deur gebruik te maak van die waaierskaleringswette. Die hoofdoelwit van hierdie projek was om ‘n metodiek te ontwikkel wat die werksverrigting van ʼn aksiaalwaaier akkuraat kan voorspel vir ʼn verskeidenheid opstellings, deur gebruik te maak van berekenings vloei meganika (BVM) sagteware en die resultate eksperimenteel te verifieer. Die projek het vier waaiers ondersoek waarvan drie van hierdie waaiers geskaleerde modelle van groot lugverkoelde aksiaalwaaiers was. Die werksverrigting van die geskaleerde waaiers (L1-, L2- en N-waaier) was met ‘n tipe A, BS 848 standaard waaier toetsfasiliteit gemeet. Die geometrie van dié waaiers was ook drie-dimensioneel opgemeet vir simulasie doeleindes. Die B-waaier, ‘n 8 lem aksiaalwaaier, wat ontwerp is deur Bruneau (1994) was slegs numeries ondersoek. Die L2-, N- en Bwaaier was gesimuleer in verskillende berekeningsdomeine deur gebruik te maak van die multi verwysingsraamwerk en gestadigde vloeiberekenings benaderings. Drie k-ε turbulensie modelle was ook ondersoek. Merkbare verskille tussen die eksperimentele en numeriese resultate van die Bwaaier was waargeneem. Goeie korrelasie tussen die eksperimentele en numeriese resultate van die geskaleerde waaiers vir ‘n wye bedryfsbestek was gevind. ‘n Vergelyking tussen die volskaal en kleinskaal waaiers se werksverrigting het egter beduidende afwykings aangetoon. Deur gebruik te maak van ‘n groot aantal selle in die berekeningsdomein was dit moontlik om ʼn verskeidenheid aksiaalvloeiwaaiers akkuraat te simuleer. Verdere navorsing wat die verhouding tussen volskaal en kleinskaal waaiers ondersoek woord aanbeveel.
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Muiyser, Jacques. "Simultaneous measurement of air flow conditions and resultant blade and gearbox loading at large-scale cooling system fans". Thesis, Stellenbosch : Stellenbosch University, 2012. http://hdl.handle.net/10019.1/71805.
Testo completoAbstract (sommario):
Thesis (MScEng)--Stellenbosch University, 2012.ENGLISH ABSTRACT: Axial flow fans used in large-scale air-cooled steam condensers (ACSCs) may operate under distorted inflow conditions. These conditions occur due to the prevailing wind conditions, the presence of buildings, and the location of the fan within the ACSC. Fans located on the periphery of the ACSC are affected the most due to their exposure to strong winds and the inner fans drawing in air past them. Distorted inflow conditions cause varying fan blade and gearbox loading conditions. The purpose of the investigation was to simultaneously measure the inlet air flow and the resultant blade and gearbox loading conditions of a single fan located on the periphery of a large-scale ACSC. Inlet and heat exchanger bundle outlet air flow velocities were measured using a combination of ultrasonic and propeller anemometers while blade loading was measured with strain gauges attached at the neck of the specific blade being monitored. Strain gauges were also attached to the low-speed fan shaft to measure gearbox loading. Measurements were recorded over a period of 8 days where it was found that increased wind resulted in increased air flow in the axial direction of the fan, which then caused a reduction in average blade loading. This was due to a decreased static pressure rise over the fan. The fan blade was found to vibrate at its own natural frequency of 6 Hz when excited by the variable aerodynamic loading. The aerodynamic loading was extracted from the measured data and was found to correlate well with previous experimental work performed by Bredell et al. (2006a). Shaft bending stresses and torque were found to oscillate at the fan’s rotational frequency of 2Hz with a large torque exerted on the shaft during fan start-up.
AFRIKAANSE OPSOMMING: Aksiaalvloeiwaaiers wat by groot lugverkoelde stoomkondensors gebruik word, werk dikwels onder verwronge inlaat lugvloei toestande wat geskied as gevolg van heersende winde, die teenwoordigheid van geboue en die posisie van die waaier in die kondensor. Waaiers wat geleë is op die rand van die kondensor word die meeste beïnvloed as gevolg van blootstelling aan die sterk winde en dwarsvloei wat deur die binneste waaiers geïnduseer word. Verwronge inlaat lugvloei veroorsaak gevolglik variërende waaierlem en ratkas belastingstoestande. Die doel van hierdie ondersoek was om terselfdetyd die inlaat lugvloei asook waaierlem en ratkas belastingstoestande van ’n enkele waaier wat op die rand van ’n grootskaalse lugverkoelde stoomkondensor geleë is, te meet. Waaier inlaat en warmteruiler uitlaat lugvloei snelhede is gemeet met ’n kombinasie van ultrasoniese- en skroefwindsnelheidsmeters terwyl die lem en ratkas belastings gemeet is met rekstrokies. Metings is oor ’n tydperk van 8 dae geneem. Die bevindinge toon dat ’n toename in windsnelheid ’n toename in aksiale lugvloei tempo, deur die waaier veroorsaak. ’n Afname in die gemiddelde lembelasting is waargeneem as gevolg van ’n afname in die waaier statiese druk. Daar is ontdek dat die waaierlem teen ’n natuurlike frekwensie van 6 Hz vibreer wanneer dit opgewek word deur die wisselende aerodinamiese belasting. Die aerodinamiese belasting is verkry uit die gemete data en vergelyk goed met die numeriese werk van Bredell et al. (2006a). Daar is ook bevind dat waaier-as buigspannings en wringkragte ossileer teen die waaier se rotasiefrekwensie van 2Hz met ’n groot wringkrag wat op die as uitgeoefen word wanneer die waaier aangeskakel word. iii
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Venter, Sarel Jacobus, e D. G. Kroger. "The effectiveness of axial flow fans in a-frame plenums". Thesis, Stellenbosch : University of Stellenbosch, 1990. http://hdl.handle.net/10019.1/15625.
Testo completoAbstract (sommario):
Thesis (PhD (Mechanical and Mechatronic Engineering)--University of Stellenbosch, 1990.260 leaves printed single pages, preliminary pages i-xxi and numbered pages Chapter 1/1.1-1.3, Chapter 2/2.1-2.17, Chapter 3/3.1.1-3.10, Chapter 4/4.1-4.18, Chapter 5/5.1-5.3, References pages R.1-R.7, Appendix A pages A.1-A.34, Appendix B pages B.1-B.34, Appendix C pages C.1-C.26, Appendix D pages D.1-D.16, Appendix E pages E.1-E.30, Appendix F pages F.1-F.39. Includes bibliography, list of tables, figures and symbols.
Digitized at 600 dpi grayscale to pdf format (OCR), using a Bizhub 250 Konica Minolta Scanner.
ENGLISH ABSTRACT: The ultimate goal of this project is to ensure a better understanding of the governing mechanisms present when flow distorting components are installed in close proximity of an axial flow fan. The effect of different parameters on the operation of axial flow fans is investigated. These parameters are divided into flow enhancing and flow reduction effects. The performance of an axial flow fan can be enhanced by changing the tip clearance, by adding a solid disc to the hub of the fan or by varying the number of fan blades. Flow reductions are caused by components such as inlet grids, walkways and their supporting structures, heat exchangers and windwalls. The effects of flow enhancing components are measured and compared to the results of other authors. The sensitivity of these effects to parameters such as the type of fan rotor and the specific system in which the rotor is installed is highlighted. The system effect (the interaction between the fan rotor and flow resistances in close proximity of each other) of individual components, as well as the combination of different components, is predicted both theoretically and experimentally. These predictions are compared to measured data relevant to the components in an installation where the system effects are present. The results are correlated to the kinetic energy flux coefficient of the flow at different locations within the installation. Experimental data obtained from a full scale unit (inlet shroud diameter of 9,216 m) are used to compare to scaled data from the model (inlet shroud diameter of 1,542 m). The hub to tip ratio of the axial flow fans investigated is 0,15. The most important conclusions are that the performance of the type of axial flow fan under investigation can be improved by reducing its tip clearance and by installing a solid disc to the downstream side of the rotor. An increase in the number of blades of the fan leads to only marginal improvements in the fan performance. The overall performance of the system can also be improved by removing some of the flow resisting components, or by changing their relative positions. All these conclusions are based on the assumption that the power input to the fan rotor remains constant.
AFRIKAANSE OPSOMMING: Die uiteindelike doel van hierdie projek is om te verseker dat die beherende meganismes wat teenwoordig is wanneer vloeiversteurende komponente in die nabyheid van 'n aksiaalwaaier geinstalleer word, beter verstaan word. Die effek van verskillende parameters op die werkverrigting van aksiaalwaaiers word ondersoek. Hierdie parameters word verdeel in vloeiverbeterings- en vloeiverminderingseffekte. Die werkverrigting van 'n aksiaalwaaier kan verbeter word deur die lempuntspeling te verstel, deur 'n soliede skyf aan die naaf van die waaierrotor te installeer, of deur die aantal lemme te verander. Die vloeiverminderings word veroorsaak deur inlaatsiwwe, loopvlakke en hul ondersteuningsstrukture, warmteruilers en windwande. Die effekte van vloeiverbeteringskomponente word gemeet en vergelyk met die resultate van ander outeurs. Die sensitiwiteit van hierdie effekte op parameters soos die tipe rotor en die spesifieke stelsel waarin die rotor geinstalleer is, word uitgelig. Die stelseleffek (die interaksie tussen die rotor van die waaier en vloei weerstande wat naby mekaar geinstalleer is) van individuele, sowel as 'n kombinasie van verskillende komponente, word teoreties en eksperimenteel voorspel. Hierdie voorspellings word dan vergelyk met eksperimentele data wat van toepassing is op die komponente in 'n installasie waar stelseleffekte voorkom. Die resultate word gekoppel aan die kinetiese energievloedkoeffisient van die vloei by verskillende posisies binne die installasie. Eksperimentele data, verkry vanaf 'n volskaaleenheid (inlaatmondstukdiameter van 9,216 m), word met die geskaleerde data van die model (inlaatmondstukdiameter van 1,542 m) vcrgelyk. Die naaf- tot hulsverhouding van die aksiaalwaaiers wat ondersoek word is 0,15. Die belangrikste gevolgtrekkings is dat die werkverrigting van die tipe aksiaalwaaier wat ondersoek word verbeter kan word deur die lempuntspeling te verminder en deur 'n soliede skyf te installeer by die stroomaf kant van die rotor. 'n Toename in die aantal lemme van die waaier lei slegs tot marginale verbeterings in die werkverrigting van die waaier. Die totale werkverrigting van die stesel kan ook verbeter word deur sommige vloeiweerstandskomponente te verwyder, of deur hulle relatiewe posisies te verander. Al hierdie gevolgtrekkings is gebasseer op die aanname dat die drywingsinset na die waaierrotor konstant bly.
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Doan, Donald Scott. "Using Motor Electrical Signature Analysis to Determine the Mechanical Condition of Vane-Axial Fans". Thesis, University of North Texas, 2002. https://digital.library.unt.edu/ark:/67531/metadc3256/.
Testo completoAbstract (sommario):
The purpose of this research was a proof of concept using a fan motor stator as transducer to monitor motor rotor and attached axial fan for mechanical motion. The proof was to determine whether bearing faults and fan imbalances could be detected in vane-axial fans using Motor Electrical Signature Analysis (MESA). The data was statistically analyzed to determine if the MESA systems could distinguish between baseline conditions and discrete fault frequencies for the three test conditions: bearing inner race defect, bearing outer race defect, and fan imbalance. The statistical conclusions for these proofs of concept were that MESA could identify all three faulted conditions.
6
Meunier, Trevor. "Design and Evaluation of a Compact Vibration Isolator for Use In Retrofit Telecommunications Fan Unit Applications". Thesis, Université d'Ottawa / University of Ottawa, 2016. http://hdl.handle.net/10393/35104.
Testo completoAbstract (sommario):
Fan vibration has become a significant issue in telecommunications environments due to increased performance and heat of internal components requiring greater airflow and higher speed fans. This thesis investigates fan vibration problems in telecommunications equipment and develops solutions to the problem in a retrofit scenario. A target value for vibration levels was determined by measuring vibration levels in an alternate existing product that exhibited no wear issues over a span of several years. Two successful vibration isolator designs were developed and implemented. The retrofit solution required minimal changes to the legacy design and achieved a large vibration reduction. The ultimate solution required extensive changes to the legacy design and achieved significant vibration reductions, with vibration levels below the target value in most scenarios. Both designs are Patent Pending.
7
Van, der Spuy Sybrand Johannes. "The design of a low-noise rotor-only axial flow fan series". Thesis, Stellenbosch : University of Stellenbosch, 1997. http://hdl.handle.net/10019.1/20977.
Testo completoAbstract (sommario):
ENGLISH ABSTRACT: A design routine was derived for designing a series of rotor-only axial flow fans. The routine was
applied by designing two different series of axial flow fans. The first design was for a general
application rotor-only axial flow fan. This fan series was designed, built and tested in co-operation
with Howden Air Industries for both research and commercial purposes. The second design was for
a low-noise fan series, which was designed, built and tested by the University of Stellenbosch for
research purposes only.
The design theory used the principle of blade cropping, meaning that one blade was designed to fit
all the different fan sizes. The fan series was designed for diameters ranging from 3 15 mm to 1000
mm. The fan rotors were designed to conform to a velocity profile of minimum exit kinetic flux. The
general application fan design was concentrated around the popular fan diameter sizes of 500 rnm,
560 mm and 630 mm and a rotor speed of 1440 rpm, using a commercially available fan series as
reference. The low-noise fan design concentrated on one fan size only, namely 630 mm, while also
making use of the principle of forward blade sweep. The remaining fan design principles stayed the
same as for the general application fan design. The F-series airfoils were used as blade sections for
both fan designs.
Both fan series were tested for fan noise and performance in accordance with the BS 848 Standards
part 1 (1980) and 2 (1985). A selection of fan diameter sizes was tested for the general application
fan to verify its perfo!"mance over a range of fan sizes. This indicated a fan series with a wide range
of efficient operation, including excellent noise characteristics. A 630 mm diameter fan was used to
test the low-noise fan series. It showed both high efficiency and low noise characteristics. The
reduction in fan noise achieved with the low-noise fan does not justi1)' the amount of work and costs
involved in the designing process, compared to the general application fan.AFRIKAANSE OPSOMMING: 'n Ontwerpsroetine vir die ontwerp van 'n reeks enkelrotor aksiaalwaaiers is ontwikkel. Die roetine is toegepas deur twee verskillende reekse aksiaalwaaiers te ontwerp. Die eerste ontwerp was vir 'n algemene toepassings enkelrotor aksiaalwaaier. Die waaierreeks is ontwerp, gebou en getoets in samewerking met Howden Air Industries vir beide navorsings - en kommersieIe doeleindes. Die tweede ontwerp was vir 'n lae geraas waaierreeks. Die reeks is ontwerp, gebou en getoets deur die Universiteit van Stellenbosch vir navorsingsdoeleindes. Die onwerpsteorie het gebruik gemaak van die beginsel van lemverkorting, waardeur een lem ontwerp is om op al die groottes waaierdeursnee te pas. Die waaierreekse is ontwerp vir waaierdeursnee tussen 315 mm en 1000 mm. Die rotors is ontwerp om 'n uitlaatsneIheidsprofiel te gee wat 'n minimum verlies in kinetiese energie toelaat. Die algemene toepassings waaierontwerp het gekonsentreer rondom die gewilde waaierdeursnee van 500 mm, 560 en 630 mm. Dit is ontwerp vir 'n rotorspoed van 1440 met 'n kommersieel beskikbare waaierreeks wat as verwysing gebruik is. Die lae geraas waaierreeks het op slegs een waaiergrootte gekonsentreer, naamlik 630 mm. Die lae geraas waaierreeks is ook ontwerp met vorentoe gekurfde lemme. Die res van die ontwerpsbeginsels was dieseIfde as vir die algemene toepassings waaierreeks. Die F-reeks vleuelprofiele is gebruik vir die lemseksies van beide waaierreekse. Beide waaiereekse is getoets vir waaiergeraas en -effektiwiteit deur gebruik te maak van die BS 848 Standaarde deel 1 (] 980) en 2 (] 985). 'n Verskeidenheid van waaierdeursnee van die algemene toepassings waaierreeks is getoets om die waaier se vertoning oor 'n gebied van waaiergroottes te bepaal. Die resuItaat was 'n waaierreeks met 'n wye gebied van effektiewe werking, asook uitstekende geraaseienskappe. 'n 630 mm Deursnee waaier is gebruik om die lae geraas waaier te toets. Die toetse het 'n waaier getoon wat beide hoe effektiwiteit en lae geraaseienskappe het. Die afname in waaiergeraas wat verkry is met die lae geraas waaier, in vergelyking met die algemene toepassings waaier, regverdig egter rue die werk en kostes verbonde aan die ontwerp van die waaierreeks nie.
8
Thiart, G. D. "A numerical procedure for predicting the effects of distorted inflow conditions on the performance of axial flow fans". Thesis, Stellenbosch : University of Stellenbosch, 1991. http://hdl.handle.net/10019.1/5747.
Testo completoAbstract (sommario):
Thesis (PhD (Mechanical Engineering))--University of Stellenbosch, 1990.Leaves printed on single pages, preliminary pages i- viii and numbered pages 1-1-R5. Includes bibliography, list of tables and figures and list of appendices. Digitized at 330 dpi black and white PDF format (OCR),using KODAK i 1220 PLUS scanner.
ENGLISH ABSTRACT: A numerical procedure for predicting the effect of inlet flow distortions on the performance of axial flow fans is proposed. The study is aimed specifically at fans of low solidity and low hub-to-tip ratios, which have attained some importance with the advent of large directly air-cooled power stations in certain arid regions of the world. The numerical model is an extension to cylindrical polar coordinates of the SIMPLEN algorithm that has been developed by the author previously. The algorithm is implemented in a computer code, FLOVAX, which solves the incompressible Navier-Stokes equations, augmented by the k-Ɛ model of turbulence, on a computational domain that is aligned with the cylindrical polar coordinate system. Several relatively simple flow problems are solved to verify the code: laminar stagnation flow, laminar flow near a rotating disk, turbulent flow near a propeller, turbulent flow through an abrupt axisymmetric expansion, and turbulent swirling flow in an annulus. Good agreement is obtained between the numerical solutions and the corresponding analytical, empirical or published experimental and numerical results. Some experimental results are also presented: measurements of shaft power, volume flow rate and static pressure rise were taken in a setup comprising an axial flow fan mounted in the wall of a wind tunnel. The wind tunnel was used to provide flow across the fan intake, thus establishing distorted inflow conditions. Detailed measurements of the velocity and static pressure distributions in the duct downstream of the fan rotor were also performed. It is clear from the results that flow across the intake of the test fan has a detrimental effect on its performance in that an increased amount of power is necessary to deliver the same flow rate as with no crossflow. In the numerical predictions, blade element theory is used to model the thrust and torque exerted by the fan blades on the air. The numerical results generally confirm the results of the experiment, although the increase in power is underestimated: an increase of only approximately half of the measured increase is predicted. Several recommendations for improvement of the numerical procedure are made.
AFRIKAANSE OPSOMMING: 'n Numeriese prosedure vir die voorspelling van die invloed van versteurings in inlaatvloei op die werking van aksiaalwaaiers word daargestel. Die studie is spesifiek gemik op waaiers van lae soliditeit en lae lempunt-tot-naafverhoudings. Waaiers van hierdie tipe het belangrikheid verwerf sedert die onlangse totstandkoming van groot lugverkoelde kragstasies in sekere droe werelddele. Die numeriese model is 'n uitbreiding na silindriese poolkoordinate van die SIMPLEN-algoritme wat voorheen deur die skrywer ontwikkel is. Die algoritme word geimplementeer in 'n rekenaarkode, FLOVAX, wat die onsamedukbare Navier-Stokes-vergelykings, aangevul deur die k-Ɛ-turbulensiemodel, oplos op 'n berekeningsgebied wat saamval met die silindriese poolkoordinaatstelsel. Verskeie relatief eenvoudige vloeiprobleme word opgelos ter verifikasie van die kode: laminere stagnasievloei, laminere vloei op 'n roterende skyf, turbulente vloei deur 'n propeller, turbulente vloei deur 'n aksiaalsimmetriese vernouing, en turbulente roterende vloei in 'n annulus. Goeie ooreenstemming tussen die numeriese oplossings en die ooreenstemmende analitiese, empiriese of gepubliseerde eksperimentele en numeriese resultate is verkry. Eksperimentele resultate word ook aangebied: metings van asdrywing, volumevloei en statiese drukstyging is geneem in 'n opstelling wat bestaan het uit 'n aksiaalwaaier wat in die wand van 'n windtonnel gemonteer is. Die windtonnel is gebruik om versteurde-invloei-toestande te genereer in die vorm van dwarsvloei oor die waaier-inlaat. Snelheids- en statiese drukverdelings in die kanaal stroom-af van die waaierrotor is ook gemeet. Dit blyk duidelik uit die resultate dat die dwarsvloei oor die inlaat van die toetswaaier 'n nadelige uitwerking het op die werking daarvan in die opsig dat meer drywing nodig is om dieselfde vloeitempo te handhaaf as wat die geval is sonder dwarsvloei. Vir die numeriese voorspellings word van lem-element-teorie gebruik gemaak om die stukrag en draaimoment wat deur die waaier op die lug uitgeoefen word, te modelleer. Die numeriese resultate bevestig oor die algemeen die eksperimentele resultate, alhoewel die drywingstoename onderskat word met sowat die helfte van die gemete toename. Verskeie aanbevelings ter verbetering van die numeriese prosedure word gemaak.
9
Visser, J. G. J. "Die invloed van versteurde inlaatvloeipatrone op aksiaalwaaiers". Thesis, Stellenbosch : Stellenbosch University, 1990. http://hdl.handle.net/10019.1/21767.
Testo completoAbstract (sommario):
Stellenbosch University. Faculty of Engineering. Dept. of Mechanical and Mechatronic Engineering.Thesis (MEng)--Stellenbosch University, 1990.
ENGLISH ABSTRACT: The causes of disturbances in the flow patterns at the inlets of axial flow fans that are used in mechanical draft cooling towers and the effects of these disturbances on the fans, were investigated. A scale model of a part of a mechanical draft cooling tower used at a power station was built for the purpose of this study. In the cooling tower the axial flow fans are arranged in a matrix configuration. It was noted from the scale model that the boundary fan was subjected to the worst inlet disturbances and this had an adverse effect on the flow it produced. Geometric alterations like the use of guide vanes and rounded inlets improved the flow through the boundary fan considerably. It was found that the performance of the fans is a function of the number of fans used and the elevation of the fans. Several tests to determine the performance of the cooling tower confirmed the results obtained from the experiments on the scale model. It was also found that the speed and direction of the prevailing wind have a significant effect on the cooling tower. Experiments to investigate the effects of cross-flow at the inlet of a fan indicated an increased flow through the fan at low cross-flow velocities and that the flow decreased at high cross-flow velocities.
AFRIKAANSE OPSOMMING: Die invloed en oorsake van versteurde inlaatvloeipatrone op aksiaalwaaiers wat in meganiese-trek koeltorings gebruik word is ondersoek. 'n Skaaimodel van 'n deel van 'n meganiese-trek koeltoring wat by 'n kragstasie gebruik word is gebou vir die doel van die studie. Die aksiaalwaaiers wat in die koeltoring gebruik word is in 'n matrikskonfigurasie gerangskik. Vanaf die skaalmodel is waargeneem dat die randwaaier die ergste versteuring by die inlaat ervaar, en gevolglik minder vloei as die res van die waaiers in die opstelling lewer. Die vloei deur die randwaaier is verbeter deur verskillende geometriese wysigings soos leilemme en inlaatafrondings aan te bring. Daar is gevind dat die werking van die waaiers in die opstelling 'n funksie van die hoeveelheid waaiers asook die grondvryhoogte is. Om die werking van die koeltoring te bepaal is verskillende toetse daarop uitgevoer. Die resultate het die geldigheid van die skaalmodel bevestig. Daar is ook gevind dat die heersende windsterkte en rigting 'n definitiewe invloed op die koeltoring uitoefen. Die invloed van 'n dwarsvloei by die inlaat van 'n enkele waaier is ook eksperimenteel ondersoek. Die resultate toon dat daar 'n vermeerdering in vloei deur die waaier by lae dwarsvloeisnelhede plaasvind. Hoë dwarsvloeisnelhede veroorsaak egter 'n vermindering in vloei.
10
Le, Roux Frederick Nicolaas. "The CFD simulation of an axial flow fan". Thesis, Stellenbosch : University of Stellenbosch, 2010. http://hdl.handle.net/10019.1/4344.
Testo completoAbstract (sommario):
Thesis (MScEng (Mechanical and Mechatronic Engineering))--University of Stellenbosch, 2010.ENGLISH ABSTRACT: The purpose of this project is to investigate the method and accuracy of simulating axial ow fans with three-dimensional axisymmetric CFD models. Two models are evaluated and compared with experimental fan data. Veri cation data is obtained from a prototype fan tested in a facility conforming to the BS 848 standards. The ow eld over the blade surfaces is investigated further with a visualization experiment comprising of a stroboscope and wool tufts. Good correlation is found at medium to high ow rates and recommendations are made for simulation at lower ow rates as well as test guidelines at the fan test facility. The results and knowledge gained will be used to amend currently used actuator disc theory for axial ow fan simulation.
AFRIKAANSE OPSOMMING: Die doel van hierdie projek is om die metode en akkuraatheid om aksiaalvloeiwaaiers met drie-dimensionele BVM modelle te simuleer, te ondersoek. Twee modelle word geëvalueer en met eksperimentele waaiertoetse vergelyk. Veri- kasie data is verkry vanaf 'n prototipe waaier wat in 'n fasiliteit getoets is en wat aan die BS 848 standaarde voldoen. Die vloeiveld oor die lemoppervlaktes word ondersoek met 'n visualisering eksperiment wat uit 'n stroboskoop en wolletjies bestaan. Goeie korrelasie word gevind vir medium tot hoë massavloeie en aanbevelings word gemaak vir die simulasie by laer massavloeie met riglyne vir toetswerk in die toets-fasiliteit. Die resultate en kennis opgedoen sal gebruik word in die verbetering van huidige aksieskyfteorie vir numeriese aksiaalvloeiwaaier simulasies.
Libri sul tema "Fans, Mechanical"
1
Eck, Bruno. Ventilatoren: Entwurf und Betrieb der Radial-, Axial- und Querstromventilatoren. 5a ed. Berlin: Springer-Verlag, 1991.
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2
Eck, Bruno. Ventilatoren: Entwurf und Betrieb der Radial-, Axial- und Querstromventilatoren. 6a ed. Berlin: Springer, 2003.
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3
European Conference on Installation Effects in Fan Systems (1990 London, England). Installation Effects in Fan Systems: European Conference, 14-15 March 1990, The Institution of Mechanical Engineers, Birdcage Walk, London. Suffolk: Published for the Institution of Mechanical Engineers by Mechanical Engineering Publications, 1990.
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4
Institution of Mechanical Engineers (Great Britain) International Conference. Power station pumps and fans: Proceedings of the Institution of Mechanical Engineers International Conference, 12-13 May 1992, Institution of Mechanical Engineers, Birdcage Walk, London. Bury St. Edmunds, Suffolk: published for IMechE by Mechanical Engineering Publications, 1992.
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5
International Conference on Fans (2004 London, England). International Conference on Fans: 9-10 November 2004 IMechE headquarters, London, UK : organized by the Fluid Machinery Group of the Institution of Mechanical Engineers (IMechE). Bury St. Edmunds: Professional Engineering Publishing for the Institution of Mechanical Engineers, 2004.
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6
Quan fang wei cai liao li xue. Taibei Shi: Ding mao tu shu chu ban gu fen you xian gong si, 2001.
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7
Quan fang wei cai liao li xue. Taibei Shi: Ding mao tu shu chu ban gu fen you xian gong si, 2001.
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8
Liu ti li xue beng yu feng ji. 2a ed. Beijing: Zhongguo jian zhu gong ye chu ban she, 1985.
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9
Yan tu gong cheng jie mian shi bie li lun yu fang fa. Beijing: Ke xue chu ban she, 2008.
Cerca il testo completoCapitoli di libri sul tema "Fans, Mechanical"
1
Marchildon, Keith, e David Mody. "Pumps, Fans, Blowers, and Compressors". In Mechanical Engineers' Handbook, 717–52. Hoboken, NJ, USA: John Wiley & Sons, Inc., 2006. http://dx.doi.org/10.1002/0471777471.ch22.
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2
Singh, Vijay Kumar, Rajeev Rathi e Arshia Kaul. "The Value Engineering Way: A Case of Industrial Fans". In Lecture Notes in Mechanical Engineering, 67–79. Singapore: Springer Singapore, 2020. http://dx.doi.org/10.1007/978-981-15-4565-8_6.
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3
Moczko, Przemysław, Jędrzej Więckowski e Piotr Odyjas. "Numerical and Experimental Testing of the WLS Series Axial Fans Used for Local Ventilation of Underground Excavations". In Lecture Notes in Mechanical Engineering, 497–509. Cham: Springer International Publishing, 2019. http://dx.doi.org/10.1007/978-3-030-04975-1_58.
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4
Sultanian, Bijay K. "Centrifugal Pumps and Fans". In Fluid Mechanics and Turbomachinery, 173–92. Boca Raton: CRC Press, 2021. http://dx.doi.org/10.1201/9781003053996-8.
Testo completo
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Sultanian, Bijay K. "Axial-Flow Pumps, Fans, and Compressors". In Fluid Mechanics and Turbomachinery, 225–60. Boca Raton: CRC Press, 2021. http://dx.doi.org/10.1201/9781003053996-10.
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Dafermos, C. M. "Admissible Wave Fans in Nonlinear Hyperbolic Systems". In Mechanics and Thermodynamics of Continua, 127–44. Berlin, Heidelberg: Springer Berlin Heidelberg, 1991. http://dx.doi.org/10.1007/978-3-642-75975-8_7.
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Shepelenko, Ihor, Yuri Tsekhanov, Michael Storchak, Yakiv Nemyrovskyi e Vitalii Cherkun. "Mechanics of Micro-cutting Using FANT". In Lecture Notes in Mechanical Engineering, 619–28. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-68014-5_60.
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8
Hurault, J., S. Kouidri, F. Bakir e R. Rey. "Experimental Investigation of Wall Pressure Fluctuations in Axial Flow Fans with Different Swept". In Fluid Machinery and Fluid Mechanics, 20–26. Berlin, Heidelberg: Springer Berlin Heidelberg, 2009. http://dx.doi.org/10.1007/978-3-540-89749-1_4.
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Mouthereau, F., O. Lacombe, J. Tensi, N. Bellahsen, S. Kargar e K. Amrouch. "Mechanical Constraints on the Development of the Zagros Folded Belt (Fars)". In Thrust Belts and Foreland Basins, 247–66. Berlin, Heidelberg: Springer Berlin Heidelberg, 2007. http://dx.doi.org/10.1007/978-3-540-69426-7_13.
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"Centrifugal Compressors and Fans". In Dekker Mechanical Engineering. CRC Press, 2003. http://dx.doi.org/10.1201/9780203911600.ch4.
Testo completoAtti di convegni sul tema "Fans, Mechanical"
1
Grimes, Ronan, David Quin, Ed Walsh, Mark Davies e Stefan Kunz. "A Theoretical and Experimental Investigation of the Scaling of Micro Fan Performance". In ASME 2003 International Mechanical Engineering Congress and Exposition. ASMEDC, 2003. http://dx.doi.org/10.1115/imece2003-41432.
Testo completoAbstract (sommario):
Mobile phones and palm top computers are following trends of increased functionality and processor speed. To allow these trends to continue, compact cooling solutions are required. One potential solution is to introduce cooling fans. However, no fan currently exists which is small enough. This paper investigates the feasibility of producing a fan on the micro scale, which could be used. Theoretical analysis predicts a reduction in efficiency as fan size is reduced. A series of geometrically similar fans was produced so that the scaling could be experimentally investigated. These fans varied in size from the macro to the micro scale. The macro scale fan, which was used as a datum, is typical of those used to cool macro scale electronic systems. The authors developed techniques for the fabrication of the smaller scale fans. These included micro electro discharge machining. Methods for testing the performance of each of these fans were also developed. The pressure flow performance of each of the fans is measured, and confirms that as the micro scale is approached fan efficiency decreases. The observed decrease in efficiency is in agreement with theoretical prediction.
2
Epple, Philipp, Matthias Semel, Henrik Smith, Oliver Litfin e Antonio Delgado. "Radial Impeller Design Optimization Matched for High Efficiency Fans". In ASME 2011 International Mechanical Engineering Congress and Exposition. ASMEDC, 2011. http://dx.doi.org/10.1115/imece2011-65450.
Testo completoAbstract (sommario):
Radial fans and blowers are widely used in many different fields, such as heater blowers or fans and blowers for vacuum cleaners. Although the impellers for these fans are already quite well optimized, it is possible to increase the efficiency of the fan matching the impeller properly to it. A very common fan optimization strategy is to increase the efficiency of the radial impeller, keeping its operating point, i.e. the flow rate of maximum efficiency. However, in most of these cases the impeller is not matched to the fan and hence this procedure will not deliver the best fan, even if the efficiency of the impeller is improved. In order to understand how an optimization of the fan has to be done, a theoretical treatment is presented. Detailed theoretical formulas are presented and discussed. In order to validate the theory, a series of well directed impellers and fans was designed, CAD models constructed and using ANSYS CFX finally the corresponding flow simulation was performed. It is shown how the impellers have to be modified in order to shift the flow rate of maximum efficiency without significant decrease in efficiency. Finally a detailed experimental study was performed at the test rig conforming the German engineering norm DIN 24 163 [1]. Here the theoretical achievements were systematically verified at the test rig for vacuum cleaner fans. It is shown how to, based on this theory, from the very beginning design the radial impellers such that they are perfectly matched to the full fan. In such a way it is shown how to increase the efficiency of radial fans and blowers substantially.
3
Kimber, Mark, Suresh Garimella e Arvind Raman. "Experimental Mapping of Local Heat Transfer Coefficients Under Multiple Piezoelectric Fans". In ASME 2006 International Mechanical Engineering Congress and Exposition. ASMEDC, 2006. http://dx.doi.org/10.1115/imece2006-13922.
Testo completoAbstract (sommario):
Piezoelectric fans have been shown to provide large enhancements in heat transfer over natural convection while consuming very little power. These fans consist of a piezoelectric material attached to a flexible cantilever. When driven at resonance, large oscillations at the cantilever tip cause fluid motion, which in turn, results in improved heat transfer rates. In this study, the local heat transfer coefficients are determined experimentally for piezoelectric fans vibrating close to an electrically heated stainless steel foil, and the entire temperature field is observed by means of an infrared camera. Various vibration amplitudes, distances from heater to fan tip (or gap), and fan pitches are considered for both single-fan and two-fan configurations in impinging orientations. Of particular interest is the increase in heat transfer performance with an additional fan present and the dependence of this increase on the variable parameters. Results show nearly uniform cooling within the envelope of vibration for single-fan experiments with small gaps, and the existence of an optimal gap distance which is dependent on vibration amplitude. The benefits of an additional fan include greater coverage area, but the resulting increase in peak convection coefficient is highly dependent on the fan pitch. Conditions exist where constructive interference is observed which causes a roughly 10% increase in peak convection coefficient while significantly increasing the coverage area. Understanding the local performance of piezoelectric fans provides an important tool to help implement these devices in practical cooling systems.
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Bidakhvidi, Mohammad Ahmadi, Rasoul Shirzadeh e Steve Vanlanduit. "Study of the Cooling Performance of Oscillating Piezoelectric Fans". In ASME 2013 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/imece2013-64280.
Testo completoAbstract (sommario):
Piezoelectric vibrating fans operating at resonance are a viable cooling technology due to its easy scalability and low power consumption. This study focuses on the characterization and optimization of the thermal performance of these miniature flapping cooling systems. Different experiments in a miniature windtunnel are conducted to investigate the cooling performance of the oscillating fans. The Strouhal number is a dimensionless parameter describing wing kinematics of flying systems. The aerodynamic propulsive efficiency of these systems is high over a narrow range of Strouhal numbers. Different St numbers were obtained and investigated, by changing the flow velocity of the win-tunnel. In practical applications different St could be obtained by combining conventional axial fans with piezoelectric fans. Both the feasibility of a single fan and array of fans is studied. For a wide range of operating coditions, including distance from heat source, dynamic tip deflection and orientation, the heat transfer performance of the piezoelectric fans is characterized.
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Corona, J. J., A. A. Kwarteng, G. Warwick, K. Kaddoura, O. Mesalhy, Q. H. Leland, L. C. Chow e J. P. Kizito. "Testing of a Cooling Fan for Wing-Bay Electro-Mechanical Actuators". In ASME 2018 5th Joint US-European Fluids Engineering Division Summer Meeting. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/fedsm2018-83480.
Testo completoAbstract (sommario):
The scope of the work is to develop a cooling system which uses wing-bay air to cool the Electro-Mechanical Actuators (EMA). The wing-bay is enclosed. The system will operate between 20% and 100% of atmospheric pressure. Using high speed fans as a means of cooling the EMAs it is important to understand the characteristics of the fan. The study also closely observed the results obtained experimentally with that of the fan scaling analysis. The fan laws can be derived from dimensionless analysis of volumetric flow rate, static pressure, and power equations. Considering the current experimental data, the fan scaling laws can be used to verify the proper nature of the fan curves when using a certain measurement at the baseline. In this study, the results have been verified for various rotational speeds and ambient pressure conditions. Consequently, there are two fans that have been tested within the loop. The first fan is a 2 bladed fan whereas the other fan has a 12 bladed propeller. The fan performance curves will determine the cooling capacities of each and provide a means to compare geometrically different fans.
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Dogruoz, M. Baris, e Gokul Shankaran. "Advances in Fan Modeling: Issues and Effects on Thermal Design of Electronics". In ASME 2012 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/imece2012-89857.
Testo completoAbstract (sommario):
Forced convection air-cooled electronic systems consist of fans to provide fluid flow through the enclosure. Typically axial flow fans, radial impellers, and centrifugal blowers fall into this category. In numerical computations of flow fields in electronic enclosures, axial fans have most commonly been abstracted as planar (2-D) rectangular or circular surfaces. In some cases, these abstract or lumped models may be used to mimic impellers and centrifugal blowers as well. All of these models rely on an experimentally derived “pressure head-flow rate” (P-Q) curve (also called “fan curve”). The experiments to obtain the fan curve should conform to the test codes published by ASME and/or AMCA. Convenience and accuracy of abstract fan models are dependent on the specific application/cooling method and the acceptable error margin. The latter for the thermal design of electronics has recently diminished considerably which led to the need of using more accurate and robust fan modeling techniques such as Multiple Reference Frame (MRF) model. The authors validated this method for different types of fans against relevant experimental data previously [1,2]. As a continuation of this earlier effort, an attempt is made to examine the thermal field computed by various fan modeling techniques including MRF for air-cooled enclosures in the present work. The results show that the temperature values obtained from lumped fan model and the MRF technique differ considerably.
7
Fritsche, Manuel, Philipp Epple e Antonio Delgado. "The Impact of the Gas Temperature and of the Relative Humidity on the Performance of Fans Operating in Drying Plants". In ASME 2018 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/imece2018-88674.
Testo completoAbstract (sommario):
In order to investigate the impact of the gas temperature and its relative humidity on the performance of fans, the similarity laws for fans were extended and verified and numerical computations with the commercial CFD solver ANSYS CFX were performed. First the accuracy of the original fan laws was verified for different operating conditions. In a second step the influence of the temperature on the fan characteristics was investigated. Finally, to include the effect of the relative humidity multiphase simulations with air and water vapor were performed. Therefore, the relative humidity was analyzed for different gas temperatures. In such a way the full influence of the temperature and of the relative humidity on the performance characteristics of radial fans operating in drying plants was obtained. These numerical results have been analyzed in detail and compared with the results predicted by the presented extended similarity laws for turbomachines.
8
Benner, Jingru, Eric Shilyuk, Jarrod Coletta, Mehdi Mortazavi, Anthony D. Santamaria, Shun Su e Tony Nguyen. "Experimental Characterization of a Novel Piezoelectric Fan". In ASME 2019 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2019. http://dx.doi.org/10.1115/imece2019-11039.
Testo completoAbstract (sommario):
Abstract Piezoelectric fans have attracted attentions in the past decades because of their low energy consumption, low noise level, light weight and reliability. A novel form of piezoelectric flapping fan is characterized experimentally and numerically. An experimental setup was built to measure the pressure and flow rate of piezoelectric fans with low static pressure at various frequencies. The fan performance curve was established. A high speed camera system was used to analyze the oscillation motion of the fan wings. The displacement of the leading edge and trailing edge of the piezoelectric fan wings are used as inputs to describe the deflection of the fan in the numerical model. The flow field obtained from the model is analyzed. The vortex shedding is observed and discussed. The pressure and flow rate obtained from the 2D numerical model are compared with the experimental results. The results provide a fundamental understanding of a piezoelectric fan with opposing oscillating wings.
9
Epple, Philipp, Matthias Semel, Bettina Willinger e Antonio Delgado. "Compact Test Rig Design for Fans and Blowers". In ASME 2014 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/imece2014-38972.
Testo completoAbstract (sommario):
In order to develop high efficiency fans and blowers the design methods are being improved continuously. The same is valid for the modern CFD (Computational Fluid Dynamics) programs, which are used in the design process in order to validate the designs. However, at the end of the development process measurements at test rigs are needed in order to verify the final design. CFD is substituting to some extend EFD (Experimental Fluid Dynamics), but still EFD is the final way to evaluate a design. Usually the universities and the industry have some test rig where measurements are done. These test rigs in general are unique and built according to a corresponding standard. However, these standards, as for example the German DIN 24 163 [1] or the European DIN EN ISO 5801 [2] prescribe only the main proportions of such test rigs while several important features are not described in detail. In particular the aerodynamic theory behind the standard is very often omitted. For example, the measurement of the pressure characteristic of a fan is performed at a pressure tab at the test chamber wall and not at the fan itself. How to assure that the pressure measured at the wall tab corresponds to the fan pressure? In this work the relevant theory behind the design of test rigs was worked out in detail for the relevant test rig features where the standards do not explain the fluid mechanical aspects. On this basis pressure and suction side test rigs were designed and completely simulated with a commercial CFD program, Ansys CFX. The goal was to develop compact test rigs according to the European DIN EN ISO 5801 [2] standard. It is shown in this work how the size of the test chamber influences the measuring results. Furthermore an in detail CFD study of a series of flow measurement devices, as inlet and Venturi nozzles, was performed. In such a way it was possible to show the influence of the dimensions of these devices on the accuracy of the measurements. Finally two test rigs were built, one for suction side and the other one for pressure side measurements. Compared to other test rigs in this category in use in the industry in Germany it was possible to reduce the size of these test rigs by a factor of about two complying with the measurement uncertainty of the DIN EN ISO 5801 standard.
10
Violette, John A., e Eric S. Loos. "Mechanical Design of a Variable Pitch Fan for Turbofan Engines". In ASME Turbo Expo 2010: Power for Land, Sea, and Air. ASMEDC, 2010. http://dx.doi.org/10.1115/gt2010-22969.
Testo completoAbstract (sommario):
The mechanical design of a new variable pitch fan system for high bypass turbofan engines is presented, offering 10–14% fuel savings for next generation turbofan engines. Comparable in weight to current fans, the new design incorporates a compact pitch change mechanism that fits within a current fan’s center body. The key to compactness is the use of multiple high strength tension/torsion straps, which support blade centrifugal loads with unique structural efficiency and redundancy, while allowing ten to fifteen degrees of blade pitch rotation. The new retention system also offers significant reduction of pitch control forces by balancing blade centrifugal twisting loads with strap restoring moments, achieving a desired pitch setting. The use of a pin root fan blade facilitates on-wing blade replacement. Fan blade incidence angles are decreased at low aircraft speeds to avoid fan stall flutter problems. Therefore, advanced engines no longer need the addition of a variable area nozzle to the exit of the fan duct to prevent flutter, saving additional weight, complexity, and cost. This new fan system offers the best solution for achieving a major improvement in turbofan engine efficiency, at the lowest weight.
Rapporti di organizzazioni sul tema "Fans, Mechanical"
1
Kantner, Colleen, Scott Young, Sally Donovan e Karina Garbesi. Ceiling Fan and Ceiling Fan Light Kit use in the U.S. Results of a Survey on Amazon Mechanical Turk. Office of Scientific and Technical Information (OSTI), luglio 2013. http://dx.doi.org/10.2172/1165855.
Testo completo
2
Courtney, R. C., e D. J. W. Piper. The gravity signature induced by the loading of an old Atlantic type margin by a quaternary submarine fan: evidence for a thick mechanical lithosphere. Natural Resources Canada/ESS/Scientific and Technical Publishing Services, 1992. http://dx.doi.org/10.4095/133486.
Testo completo