Volume 3B: Fluid Applications and Systems最新文献

{"title":"Experimental Approach to Predict the Residual Axial Thrust in Centrifugal Pumps","authors":"Giulio Elicio, F. Annese","doi":"10.1115/ajkfluids2019-4883","DOIUrl":"https://doi.org/10.1115/ajkfluids2019-4883","url":null,"abstract":"\u0000 The residual axial thrust of a centrifugal pump is the vector resultant of the hydraulic components of impellers and sleeves, the momentum force and other imbalance forces and is bear by the thrust bearing. Among all the components, the hydraulic is by far the most important because it is typically one order of magnitude bigger than the others and the final residual axial thrust itself; but it is also the most difficult to calculate or estimate. This is mainly due a lot of uncertainties in the definition of the pressure distribution in the sidewall gap, dependent on the rotational speed, the leakages through the annular seals, the inlet swirl to the sidewall, the axial alignment of the impeller with the stator, the geometric tolerances and the pump operation.\u0000 In this paper an experimental approach to validate and calibrate the formulation to predict the hydraulic component of the impellers is presented. The typical formulation to evaluate the parabolic behavior of the pressure distribution is based on a series of coefficients, coming from literature, to consider all the above-mentioned influences. This formulation can be considered satisfying when dealing with pumps with back-to-back arrangement of the impellers on the rotor, since the hydraulic components are almost balanced. But with in-line configuration, all the hydraulic components of the impellers act against one direction and most of their force can be balanced by means of a balance drum, much more reliable than a balance disk. An experimental test campaign on a high energy diffuser pump was performed. The pump was equipped with load cells and temperature probes on the thrust bearing, and a special balancing line with a regulating bleed-off valve whose aim was to partialize the flowrate routed from the back side of the balancing drum to the suction. By throttling the bleed-off valve, it was possible to measure the hydraulic components of the impellers in very different operating conditions of the balancing drum, at different rotational speed and at different flowrates included zero residual axial thrust capability. As results of this campaign, once calibrated the coefficients on the full-scale pump, it is possible to calculate the residual axial thrust based on specific pressure measurements of the model test of a stage hydraulic; this also allows a thorough optimization of the thrust bearing selection.","PeriodicalId":270000,"journal":{"name":"Volume 3B: Fluid Applications and Systems","volume":"30 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-07-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121780225","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Evaluate a New Pump Design Using CFD Simulation","authors":"H. Ding, B. Greenfield","doi":"10.1115/ajkfluids2019-5657","DOIUrl":"https://doi.org/10.1115/ajkfluids2019-5657","url":null,"abstract":"\u0000 This paper describes how CFD simulations were used to help evaluating a centrifugal pump performance. The simulated pump was designed totally from scratch. Many aspects of pump performance characteristics were predicted based on the geometry generated using a pump design software. Especially the effects of the free spin of the 3rd rotor in a 3 stage pump assembly on overall performance were evaluated. Pump models, simulation techniques, and simulation approaches will be presented in detail. Simulation results will be discussed and compared with available test data.","PeriodicalId":270000,"journal":{"name":"Volume 3B: Fluid Applications and Systems","volume":"33 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-07-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114279320","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Capturing S-Shape of Pump-Turbines by CFD Simulations Using an Anisotropic Turbulence Model","authors":"E. Casartelli, L. Mangani, A. D. Rı́o, A. Schmid","doi":"10.1115/ajkfluids2019-5663","DOIUrl":"https://doi.org/10.1115/ajkfluids2019-5663","url":null,"abstract":"\u0000 Pump-turbines cope very well with modern electricity-market demand, having high operational flexibility and storage capabilities. Nevertheless, dynamic operation of these machines can lead to very challenging transient conditions, depending on the shape of the characteristic. Mechanical integrity can be correspondingly affected. Therefore assessment of the characteristic during the design phase, i.e. before model testing, is of crucial importance.\u0000 In the past years different attempts to accurately compute the characteristic under steady (i.e. fix point) and transient conditions have been undertaken using RANS CFD. While the SST turbulence model has become the reference for machine design, it often fails for conditions close to or around instabilities. Its strength to accurately predict separation close to sound conditions (i.e. mild part- and over-load) is no more helpful. Under unstable conditions, which are characterized by continuous unsteady vortex formation, turbulence isotropy as assumed by linear two equation models is no more the right choice.\u0000 Accordingly a turbulence model able to capture anisotropy, EARSM (Explicit Algebraic Reynolds Stress Model), has been implemented in an in-house code and used for the computation of the characteristic of various machines, stable and unstable, in order to assess the model performance.\u0000 In this paper computations of three different machines in turbine mode are presented. Results using steady boundary conditions (BC) in the unstable region as well as transient BC like load-rejection and runaway are computed with EARSM, showing its superiority compared to linear two equation models.","PeriodicalId":270000,"journal":{"name":"Volume 3B: Fluid Applications and Systems","volume":"23 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-07-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124513456","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"An Experimental Study of Influence of Slits in Throat Position on Suppression of Cavitation Instabilities in Liquid Propellant Rocket Inducer","authors":"Moena Kanamaru, Y. Kamikura, S. Kawasaki, T. Shimura, Igarashi Yuka","doi":"10.1115/ajkfluids2019-4838","DOIUrl":"https://doi.org/10.1115/ajkfluids2019-4838","url":null,"abstract":"\u0000 Experiments of an inducer with symmetric slits were conducted. The purpose of the study is to explore the suppression effect on cavitation instabilities by slits. The slits are located in a throat position in each blade and it means symmetric slits. The experiments are done through measuring pressure fluctuation in the flow field and shaft displacement and visualization using high speed camera. In this study, the head performance, the suction performance, the cavity length and the occurrence range and the strength of the cavitation instabilities are compared with the results of inducer without slit. As a result, the slit in throat position does not give bad effect on head performance, improves suction performance, and has a relation to suppression of oscillation of cavitation instabilities because of the suppression effect of cavity length, although the occurrence range of super-synchronous rotating cavitation unfortunately increases because the cavity develops slowly.","PeriodicalId":270000,"journal":{"name":"Volume 3B: Fluid Applications and Systems","volume":"62 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-07-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126098905","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Analysis of a Centrifugal Pump Equipped With an Axial Rotor With Variable Speed","authors":"A. Bosioc, D. Mos, S. Muntean, L. Anton","doi":"10.1115/ajkfluids2019-5617","DOIUrl":"https://doi.org/10.1115/ajkfluids2019-5617","url":null,"abstract":"\u0000 In the last two decades the energy market policy was focused on development of renewable energy. The renewable energy (solar and wind power) induces a fluctuating component of the electrical grid. The solution to compensate fluctuating energy is provided by the hydraulic turbines in order to produce energy in a short time and the pumps units in order to use the energy excess.\u0000 In order to ensure higher flow rate for the storage pumps, the units have constructive differences besides regular. Consequently, the complex shape of the suction-elbow with symmetrical geometry generates unsteady flows which are ingested by the impeller. These phenomena induce stronger unsteady flow conditions, such as stall, wakes, turbulence and pressure fluctuations, which affect the overall behavior of the pump providing vibration, noise and radial and axial forces on the rotor.\u0000 Alternatively, an axial rotor can be installed in front of the impeller. In this case, the flow non-uniformity will be decreased and the static pressure will be increased at the pump impeller inlet. Consequently, the efficiency behavior practically remains unchanged while the cavitational behavior is improved. Recently, a new concept was explored in order to assess the cavitational behavior on a wide range operation of the pump. The new concept proposes variable speed for the axial rotor, while the speed of the pump impeller remains constant. Accordingly, this new concept is experimentally and numerically investigated in the paper. First, the paper presents the 3D numerical investigation of the pump impeller combined with an axial rotor. The axial rotor is investigated at variable speed (between 2000 and 3000 rpm) while the pump impeller has constant speed of 2500 rpm. The minimum static pressure and the static pressure coefficient are analyzed in order to assess the new method. Second the mechanical design of the solution, for testing on the laboratory is presented. The solution contains an innovative clutch for controlling the variable speed of the axial rotor using magneto-rheological (MR) fluids. Thirdly, the experimental results concentrates on MR clutch operating regimes and the pump efficiency analysis. The MR clutch was installed between the driven electrical motor and the pump, three regimes were investigated: runaway speed for the axial rotor, clutch with MR fluid inside with and without magnetic field applied on it. The conclusions are drawn in the last section.","PeriodicalId":270000,"journal":{"name":"Volume 3B: Fluid Applications and Systems","volume":"4 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-07-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129532038","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Optimizing Pump Selection for Energy Efficiency Across Multiple Operating Conditions Using True Weighted Efficiency (TWE)","authors":"T. Dahl","doi":"10.1115/ajkfluids2019-4777","DOIUrl":"https://doi.org/10.1115/ajkfluids2019-4777","url":null,"abstract":"\u0000 Energy efficiency is emphasized more actively across the pump industry. Legislation in the European Union and in the United States utilize new energy efficiency ranking metrics, but neither of these methods are conveniently applied to customer specified load conditions. True Weighted Efficiency, or TWE, is introduced as a general-purpose, universal pump efficiency metric for pumps operating under multiple operating conditions.\u0000 The TWE is derived accurately from first principles, using generalized load profiles that include control curves, multiple discrete operating points based on those control curves, and the time of operation at each operating point.\u0000 A pump selection/optimization program is used to numerically demonstrate the TWE method. Various examples are presented, contrasting candidate pumps based on three different optimization strategies. The study reveals that the pump with the best design point efficiency may not be the best choice from a TWE or an evaluated cost perspective.\u0000 This method is applicable to rotodynamic or positive displacement pumps operating at fixed or variable speed, on/off operation, throttle control, or by-pass control. and other turbomachinery as well. The TWE methodology, when combined with a pump selection/optimization program, will help practitioners design systems that reduce energy consumption for new or reconfigured pump applications.","PeriodicalId":270000,"journal":{"name":"Volume 3B: Fluid Applications and Systems","volume":"225 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-07-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115946996","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Visualization of Oil Droplets Distribution in a Rotary Compressor","authors":"Puyuan Wu, Jun Chen, P. Sojka","doi":"10.1115/ajkfluids2019-5207","DOIUrl":"https://doi.org/10.1115/ajkfluids2019-5207","url":null,"abstract":"\u0000 A rotary compressor relies on an eccentric rolling piston, which rotates at high speed, to compress gas in the compression chamber. The oil in the rotary compressor is used for lubricating the bearing and sealing the clearance of sliding parts. However, the oil can exhaust from the rotary compressor by the refrigerant flow and reduce the reliability of the compressor as a result. Thus, studying the behavior of oil droplets distribution in a rotary compressor is a major challenge for manufacturers who rely on CFD tools to predict the multiphase flow. By modifying a rotary compressor, the oil behavior inside the cylinder is observed and recorded by a high-speed imaging system. In the current phase, multiple targeted locations, including the space between the bearing housing and the stator, and the space above the stator are measured in different conditions. The number, size, velocity, and morphology of oil droplets are analyzed based on multiple snapshots. The result can assist designers in improving the CFD analysis of compressors and ultimately reducing the oil discharge rate (ODR).","PeriodicalId":270000,"journal":{"name":"Volume 3B: Fluid Applications and Systems","volume":"22 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-07-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121046740","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Assessment of Noise Signature for a Cavitating Centrifugal Pump","authors":"Christopher Stephen, Kumaraswamy Sivasailam","doi":"10.1115/ajkfluids2019-5132","DOIUrl":"https://doi.org/10.1115/ajkfluids2019-5132","url":null,"abstract":"\u0000 In recent days, sophisticated instruments have emerged to obtain an online measurement of performance parameters from centrifugal pump of different kinds and the signals can be directed to the hands of pump user through mobile application. With this in mind, a centrifugal pump of low specific speed was chosen for cavitation studies from 80% to 120% of flow rate and for three different speeds. An assessment was carried out for cavitation noise signature from those operating condition of pumps. The result of cavitation noise based on peak magnitude as well as average of noise revealed a nature and it depends on the flow rate with respect to nominal flow rate. The noise envelope for the flow rate at best efficiency and above was having similar trend whereas at flows less than duty point it was totally different. So the criteria for finding the deviation in noise cannot be uniform for all flow rates. In this paper, the method adapted was to impose a trend line to the measured cavitation noise information to find out the deviation with respect to normal operating condition. It was concluded that detection of abnormality in pumps due to cavitation effects requires the operating condition to be diagnosed first and the proper criteria for deviation in noise has to be imposed.","PeriodicalId":270000,"journal":{"name":"Volume 3B: Fluid Applications and Systems","volume":"48 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-07-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116465129","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Redesign and Performance Analysis of Medium Flow Coefficient Centrifugal Compressor","authors":"K. Yousef, A. Engeda, A. Hegazy","doi":"10.1115/ajkfluids2019-4903","DOIUrl":"https://doi.org/10.1115/ajkfluids2019-4903","url":null,"abstract":"\u0000 In-house design/analysis program is used in this study to redesign and predict the entire performance of an existing centrifugal compressor. The centrifugal compressor experimental data from a cooperative company is validated first with the 3D CFD simulation for a single passage flow. The validation shows an acceptable performance discrepancy between experimental data and CFD for the existing impeller. Then, a redesign procedure by the in-house program is carried out to get more efficient impeller based on the experimental data. This redesigned impeller is re-implemented in the CFD simulation to be compared with in-house program analysis data. The validation shows a good performance comparison between CFD and in-house program for the redesigned impeller. Moreover, this procedure succeeds to improve the redesigned stage efficiency and work coefficient with 6.79%, and 10.55% compared to the experimental impeller, respectively.","PeriodicalId":270000,"journal":{"name":"Volume 3B: Fluid Applications and Systems","volume":"62 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-07-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116908207","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Aerodynamic Design and Assessment of a Compact, Single Stage Axial Fan for Low Noise Emission","authors":"D. Kessler, D. Giesecke, J. Friedrichs, Jörg Leuschner","doi":"10.1115/ajkfluids2019-5070","DOIUrl":"https://doi.org/10.1115/ajkfluids2019-5070","url":null,"abstract":"\u0000 Axial fans used in automotive and especially in locomotive cooling systems have to follow several, partially contrary specifications. In addition to geometrical and aerodynamic specifications, acoustic limits must be taken into account for new fan stage designs. Legislation will tweak axial fan requirements in the future further and further to lower their noise emission and maximize their efficiency.\u0000 The main focus of this paper is to design and test a single stage axial fan for locomotive cooling systems with high aerodynamic efficiency and low noise emissions. The fan stage is designed to be installed in a so-called tower construction. The available construction space is limited. Therefore, special attention is paid to reduce the axial length. Extensive blade sweep and dihedral are implemented in the design process. The fan stage design is validated by experimental tests including aerodynamic and acoustic studies.\u0000 During the aerodynamic studies, it was found that an often used approximation about the static pressure downstream the fan cannot be applied. Downstream the fan stage no further components are installed. Therefore, the static pressure at this position must be approximated. An alternative approach is developed using the results of additional studies including a downstream pipe and scaling factors. The results of the approach are plausible.\u0000 The acoustic tests were carried out at a fan test facility at TU Braunschweig. To evaluate the impact of the halls acoustic repercussion on the test results, different tests were done. Additionally, another axial fan was tested which has been investigated a few years ago in an acoustic test chamber.\u0000 The studies show the positive effect of the design methodology on aerodynamic and acoustic of the fan stage. All requirements were achieved as well as a reduction of the axial length of the fan stage.","PeriodicalId":270000,"journal":{"name":"Volume 3B: Fluid Applications and Systems","volume":"275 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-07-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134619129","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}