{"title":"Experimental Investigations of a Comb-Like Film Cooling Scheme","authors":"Hao-Ming Li, W. Ghaly, I. Hassan","doi":"10.1115/ajkfluids2019-4695","DOIUrl":"https://doi.org/10.1115/ajkfluids2019-4695","url":null,"abstract":"\u0000 The performance of a simple slot is perfect, but it does not have structural integrity. A new advanced cooling scheme with perfect performance and practical structural integrity is presented. Based on the crucial effect of the counter-rotating vortex pair (CRVP) on the film cooling effectiveness (η), the new scheme is composed of a comb-like structure and a blind slot, in which the comb structure maintains the mechanical strength, and the blind slot is intended to eliminate the CRVP and produce a smooth coolant film. The new scheme is investigated experimentally with the transient thermochromic liquid crystal (TLC) technique. Two classic geometries, the cylindrical hole and the simple slot, were also measured. The agreement of their results with the published data validated the present experimental facilities. The experimental results of the Comb scheme demonstrated that, with practical structural integrity, the new scheme has perfect performance, which bears comparison with the simple slot. Consequently, the success of the Comb scheme proved the crucial CRVP effect on η.","PeriodicalId":270000,"journal":{"name":"Volume 3B: Fluid Applications and Systems","volume":"13 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":"126542877","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}
Shun Xu, B. Ji, X. Long, Z. Qian, Gui-bin Li, Jia-jian Zhou
{"title":"Numerical Investigation of Tip Leakage Vortex Cavitation in Axial Waterjet Pump With Different Tip Gap Sizes","authors":"Shun Xu, B. Ji, X. Long, Z. Qian, Gui-bin Li, Jia-jian Zhou","doi":"10.1115/ajkfluids2019-4990","DOIUrl":"https://doi.org/10.1115/ajkfluids2019-4990","url":null,"abstract":"\u0000 The flow field in the tip region of the axial-flow waterjet pump is very complex. Although it has been studied for many years, many relevant phenomena have still been a puzzle. In present paper, many detailed data on instantaneous inner structures of the tip leakage flow and evolution of the tip leakage vortex cavitation with different tip gap sizes are offered. The numerical simulation has been conducted by using SAS turbulence model and ZGB cavitation model to understand the cavitation-vortex interaction mechanism. The predicted cavitation performance exhibits a reasonable agreement with the experimental results. Based on the illustration, with the impeller tip gap size decreasing, the cavitation area in rotating region gradually decreases. The cavitation development enhances vorticity production in an axial-flow waterjet pump. Vortices are mainly located at the impeller tip leakage region. The analysis of the relative vorticity transport equation indicates that the baroclinic torque term and the vortex dilation term have significant effects on cavitation, the main contributor to vortex generation is the vortex dilation term. In addition, in the impeller tip region, the effect of viscous diffusion term cannot be ignored, and the cavitation area has a larger amplitude of pressure pulsation.","PeriodicalId":270000,"journal":{"name":"Volume 3B: Fluid Applications and Systems","volume":"135 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":"122427063","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}
G. Chaudhari, S. Channiwala, Samip P. Shah, D. Kulshreshtha
{"title":"Flow Visualization Study of Jet and Bucket Interactions in Traditional and Hooped Pelton Runner","authors":"G. Chaudhari, S. Channiwala, Samip P. Shah, D. Kulshreshtha","doi":"10.1115/ajkfluids2019-4974","DOIUrl":"https://doi.org/10.1115/ajkfluids2019-4974","url":null,"abstract":"\u0000 This paper aims to study the flow pattern in and around a bucket of a Traditional and a Hooped Pelton runner at single injector operation and illustrates different stages of jet interaction. High speed photography is used to study the flow pattern, keeping the camera in different positions relative to the jet and to the bucket. It is concluded from the results that the flow visualization study, provides exceptional observations with an absolute frame of reference to mark the bucket duty period of a single-jet Pelton runner. The small scale models display erosion damages at the bucket lips, this indicated that the high pressure occur in the early stage of interaction. This fact is substantiated by the present flow visualization studies for the first time. The uncertainty of the free surface outflow within the Pelton turbine bucket establishes good documentation. The results are helpful to know the interaction between the jet and bucket of Pelton turbine.","PeriodicalId":270000,"journal":{"name":"Volume 3B: Fluid Applications and Systems","volume":"1 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":"129673030","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":"CFD-Based Hydraulic Design and Manufacturing of a Multistage Low Specific-Speed Diffuser Pump","authors":"M. V. D. Schoot, K. Bruurs, Eric van der Zijden","doi":"10.1115/ajkfluids2019-5661","DOIUrl":"https://doi.org/10.1115/ajkfluids2019-5661","url":null,"abstract":"\u0000 A multistage low specific-speed diffuser pump was designed to achieve very good hydraulic performance with a newly designed integrated diffuser, crossover and return guide vane. The diffuser was designed using a continuous crossover design. The design space of this diffuser was limited because of the usage of a mechanical pump design from a similar existing pump. This paper presents the simulation-based design of this new pump and the role that simulation can play in the manufacturing process.\u0000 A new diffuser has been designed to obtain optimum efficiency and to ensure that the pump will operate most of its time very close its best efficiency point. The new diffuser was designed using an approach where the diffuser vane was stretched to completely cover the area starting just behind the impeller trailing edge towards the eye of the next stage impeller. This means that the diffuser vanes should now convert velocity into pressure, guide the fluid to the next stage impeller eye while reducing the swirl and uniformizing the flow. The shape of the diffuser has been optimized using response surfaces that were created using Computation Fluid Dynamics (CFD). This way, a diffuser with a minimum amount of losses was obtained, due to smooth and gradual area changes of the waterway.\u0000 The final design incorporating this diffuser was analyzed using steady-state CFD to create the full performance curve. The design was transferred into a real physical product by manufacturing it. The resulting casting of the diffuser component was scanned using a 3D scanner. The 3D model of the scan was used to make a comparison using CFD between the performance of the designed and the manufactured diffuser. This provided understanding in how deviations due to the manufacturing process influence the performance. Finally, the complete pump underwent a performance test and its results closely matched the performance as calculated using CFD.","PeriodicalId":270000,"journal":{"name":"Volume 3B: Fluid Applications and Systems","volume":"43 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":"121503224","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}
Y. Katayama, Y. Hosoi, Y. Fukuda, S. Watanabe, S. Tsuda, Yoshihide Mori, Kazuyoshi Ito
{"title":"Experimental Investigation on Cavitation Performance of Torque Converter Using Transparent Model","authors":"Y. Katayama, Y. Hosoi, Y. Fukuda, S. Watanabe, S. Tsuda, Yoshihide Mori, Kazuyoshi Ito","doi":"10.1115/ajkfluids2019-4906","DOIUrl":"https://doi.org/10.1115/ajkfluids2019-4906","url":null,"abstract":"\u0000 In this study, we experimentally investigated the influence of the amount of dissolved air in working fluid and the rotation speed ratio of turbine to pump elements on cavitation phenomenon in automotive torque converter. In order to directly observe the cavitation phenomenon, transparent model was used. The applied charge pressure was varied to change the significance of cavitation. The pump and turbine torques were simultaneously measured to clarify the relation between torque performance and cavitation phenomenon. As a result, the cavitation region was found to depend on the speed ratio; cavitation occurred on the suction side of turbine blades at low speed ratios while in the pump region at high speed ratios. The effect of the amount of dissolved air was significant, which enhanced the growth of cavitation bubbles through the deposition of dissolved air. In such cases, with the further decrease of charge pressure, a large number of gaseous cavitation bubbles appeared in the whole flow passage. The torque performance was deteriorated at this stage.","PeriodicalId":270000,"journal":{"name":"Volume 3B: Fluid Applications and Systems","volume":"90 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129676181","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}