Araz Rezavand Hesari, Anthony Munoz, Maxime Coulaud, S. Houde, Yvan Maciel
For Francis turbines, speed-no-load represents one of the most detrimental operating conditions, marked by significant pressure and strain fluctuations on the runner. Mitigating these fluctuations necessitates a comprehensive understanding and characterization of the flow phenomena responsible for their generation. This paper presents an experimental investigation of the flow at the inlet of a Francis turbine runner model operating in speed-no-load condition using high-speed stereoscopic and endoscopic particle image velocimetry. The measurements are made in a radial-azimuthal plane that covers the vaneless space and a large region in the interblade channel. This study marks the first-time measurement of critical flow phenomena at this operating point, performed in the runner. Instantaneous and average velocity fields are analyzed, along with other statistical data. The results confirm the stochastic nature of the flow at speed-no-load but also highlight the general structure of the flow observed in other studies. The high velocity fluctuations on the suction side are associated with a backflow extending into the vaneless space and a circulation zone occasionally generated by this backflow. Both phenomena are frequently present, but fluctuate stochastically. Additionally, two other circulation zones intermittently form on the pressure side of the blades. The presence of vortices, smaller than the circulation zones, near the blade's leading edge correlates with the backflow intensity.
{"title":"The Measured Flow at the Inlet of a Francis Turbine Runner Operating in Speed No-load Condition","authors":"Araz Rezavand Hesari, Anthony Munoz, Maxime Coulaud, S. Houde, Yvan Maciel","doi":"10.1115/1.4065384","DOIUrl":"https://doi.org/10.1115/1.4065384","url":null,"abstract":"\u0000 For Francis turbines, speed-no-load represents one of the most detrimental operating conditions, marked by significant pressure and strain fluctuations on the runner. Mitigating these fluctuations necessitates a comprehensive understanding and characterization of the flow phenomena responsible for their generation. This paper presents an experimental investigation of the flow at the inlet of a Francis turbine runner model operating in speed-no-load condition using high-speed stereoscopic and endoscopic particle image velocimetry. The measurements are made in a radial-azimuthal plane that covers the vaneless space and a large region in the interblade channel. This study marks the first-time measurement of critical flow phenomena at this operating point, performed in the runner. Instantaneous and average velocity fields are analyzed, along with other statistical data. The results confirm the stochastic nature of the flow at speed-no-load but also highlight the general structure of the flow observed in other studies. The high velocity fluctuations on the suction side are associated with a backflow extending into the vaneless space and a circulation zone occasionally generated by this backflow. Both phenomena are frequently present, but fluctuate stochastically. Additionally, two other circulation zones intermittently form on the pressure side of the blades. The presence of vortices, smaller than the circulation zones, near the blade's leading edge correlates with the backflow intensity.","PeriodicalId":504378,"journal":{"name":"Journal of Fluids Engineering","volume":"32 16","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-04-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140663298","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}
Nathan P. Hagstrom, Matthew L. Gallagher, Thomas R. Chase
Existing analytical flow models for predicting flow rate at microscale seal displacements are limited to two separate domains. The first assumes a small channel length to height aspect ratio at relatively large seal displacements. The second assumes a large channel length to height aspect ratio at relatively small seal displacements. A piecewise analytical model for compressible flow is developed here to enable predicting flow rates in valves with fluid pathways of any aspect ratio. The new model is validated by numerical studies and experiment. The results are applicable to flat valve seals having a cylindrical seal boss feature with fluid passage length to height aspect ratios ranging from 3.3 to 800. The new model is particularly useful for the design of microvalves and macro-scale valves with small actuator displacements.
{"title":"Compressible Flow Through Flat Valve Seals at Microscale Displacements","authors":"Nathan P. Hagstrom, Matthew L. Gallagher, Thomas R. Chase","doi":"10.1115/1.4065383","DOIUrl":"https://doi.org/10.1115/1.4065383","url":null,"abstract":"\u0000 Existing analytical flow models for predicting flow rate at microscale seal displacements are limited to two separate domains. The first assumes a small channel length to height aspect ratio at relatively large seal displacements. The second assumes a large channel length to height aspect ratio at relatively small seal displacements. A piecewise analytical model for compressible flow is developed here to enable predicting flow rates in valves with fluid pathways of any aspect ratio. The new model is validated by numerical studies and experiment. The results are applicable to flat valve seals having a cylindrical seal boss feature with fluid passage length to height aspect ratios ranging from 3.3 to 800. The new model is particularly useful for the design of microvalves and macro-scale valves with small actuator displacements.","PeriodicalId":504378,"journal":{"name":"Journal of Fluids Engineering","volume":"60 7","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-04-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140662455","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":"Passively Enhanced Vortex-Induced Vibration Response of Side-by-Side Cylinders in Turbulent Flow","authors":"Y. H. Irawan, Syed Ahmad Raza, M. Chern","doi":"10.1115/1.4065302","DOIUrl":"https://doi.org/10.1115/1.4065302","url":null,"abstract":"","PeriodicalId":504378,"journal":{"name":"Journal of Fluids Engineering","volume":"23 2","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-04-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140697451","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}
Jingzu Yee, Daichi Igarashi, Shun Miyatake, A. Yamanaka, Yoshiyuki Tagawa
{"title":"Morphological Features of a Splashing Drop Extracted Using Explainable AI","authors":"Jingzu Yee, Daichi Igarashi, Shun Miyatake, A. Yamanaka, Yoshiyuki Tagawa","doi":"10.1115/1.4065304","DOIUrl":"https://doi.org/10.1115/1.4065304","url":null,"abstract":"","PeriodicalId":504378,"journal":{"name":"Journal of Fluids Engineering","volume":"26 16","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-04-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140696814","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":"LES/Lagrangian-Particle-Simulation of a Supersonic Reactive Turbulent Planar Jet","authors":"Jiabao Xing, Tomoaki Watanabe, K. Nagata","doi":"10.1115/1.4065301","DOIUrl":"https://doi.org/10.1115/1.4065301","url":null,"abstract":"","PeriodicalId":504378,"journal":{"name":"Journal of Fluids Engineering","volume":"24 3‐4","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-04-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140695090","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":"Direct Numerical Simulation On Millimeter-Sized Air Bubbles in Turbulent Channel Flow","authors":"Sangwon Kim, Nobuyuki Oshima, H. Park, Y. Murai","doi":"10.1115/1.4065300","DOIUrl":"https://doi.org/10.1115/1.4065300","url":null,"abstract":"","PeriodicalId":504378,"journal":{"name":"Journal of Fluids Engineering","volume":"16 17","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-04-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140696603","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}
The design and optimization of propellers for unmanned aerial vehicles (UAVs) are essential for optimal performance and high efficiency. This study presents a numerical investigation of the aerodynamic performance of coaxial octocopters using openfoam as flow solver. While the aerodynamic performance is affected by many parameters, the current study focuses on four main parameters: the propeller type, the horizontal and vertical separation distances between the propellers, and the ratio between the rotational speeds of the upper propeller and the lower one. To find the minimum number of simulations to be performed within defined limits, and reduce the number of computational fluid dynamics (CFD) simulations that cause high computational cost, Taguchi method was employed. In this study, average thrusts were calculated for the preliminary design of the octocopter by examining an isolated single propeller and dual- and quad propellers taking their rotation directions into account. The Taguchi design matrix revealed that for all cases investigated, the propeller type is the most dominant design parameter followed by the velocity ratio of the upper propeller to the lower one (nU/nL) and vertical (z/D) and horizontal (ℓ/D) orientation of coaxial propellers. However, it was shown that ℓ/D and z/D may play a significant role in vortex formation and pressure fluctuations which should be considered as design criteria for coaxial octocopters associated with flow attributes. The results showed that the aerodynamic performance parameters are not dependent on all the selected parameters, and demonstrated that the selected propeller designs improved aerodynamic performance.
{"title":"Aerodynamic Performance Evaluation of a Coaxial Octocopter Based on Taguchi Method","authors":"Evren Geydirici, Kuzey C. Derman, S. Cadirci","doi":"10.1115/1.4065229","DOIUrl":"https://doi.org/10.1115/1.4065229","url":null,"abstract":"\u0000 The design and optimization of propellers for unmanned aerial vehicles (UAVs) are essential for optimal performance and high efficiency. This study presents a numerical investigation of the aerodynamic performance of coaxial octocopters using openfoam as flow solver. While the aerodynamic performance is affected by many parameters, the current study focuses on four main parameters: the propeller type, the horizontal and vertical separation distances between the propellers, and the ratio between the rotational speeds of the upper propeller and the lower one. To find the minimum number of simulations to be performed within defined limits, and reduce the number of computational fluid dynamics (CFD) simulations that cause high computational cost, Taguchi method was employed. In this study, average thrusts were calculated for the preliminary design of the octocopter by examining an isolated single propeller and dual- and quad propellers taking their rotation directions into account. The Taguchi design matrix revealed that for all cases investigated, the propeller type is the most dominant design parameter followed by the velocity ratio of the upper propeller to the lower one (nU/nL) and vertical (z/D) and horizontal (ℓ/D) orientation of coaxial propellers. However, it was shown that ℓ/D and z/D may play a significant role in vortex formation and pressure fluctuations which should be considered as design criteria for coaxial octocopters associated with flow attributes. The results showed that the aerodynamic performance parameters are not dependent on all the selected parameters, and demonstrated that the selected propeller designs improved aerodynamic performance.","PeriodicalId":504378,"journal":{"name":"Journal of Fluids Engineering","volume":"31 4","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-04-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140699445","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}
An-qi Guan, Feng-ping Zhong, Chang Qiu, Zhi-jiang Jin, J. Qian
Cage-typed sleeve control valve (CSCV) is the key basic equipment in direct coal liquefaction project. The working condition of CSCV has the characteristics of high pressure difference, high velocity and high solid content. There is a general problem of liquid-solid two-phase erosion wear in CSCV, which is easy to lead to the failure of internal structure in the valve cage. Therefore, it is necessary to study erosion wear characteristics of internal structure in the valve cage. Based on the actual situation of erosion wear in the valve cage, the simplified T-shaped flow path is designed, and the accuracy of the liquid-solid two-phase flow model and the erosion prediction model are verified; The flow characteristics and erosion wear characteristics of T-shaped flow path under different working conditions are studied; Based on the simulation results of different structural parameters and boundary conditions, the erosion wear of T-shaped flow path is predicted and calculated by response surface method, and the prediction formula of maximum erosion rate is obtained. The formula allows for the rapid determination of optimized flow path structural parameters to reduce damage to the valve from erosion and wear. This work can quickly predict the erosion wear rate of the key areas in the valve cage, which can provide a certain reference value for the life prediction and structural optimization of CSCV, and it can also benefit safety and maintenance of coal liquefaction system.
笼式套筒调节阀（CSCV）是煤直接液化项目的关键基础设备。CSCV 工况具有压差大、流速高、含固量高等特点。CSCV 普遍存在液固两相冲蚀磨损问题，容易导致阀笼内部结构失效。因此，有必要对阀笼内部结构的冲蚀磨损特性进行研究。根据阀笼冲蚀磨损的实际情况，设计了简化的 T 形流道，验证了液固两相流模型和冲蚀预测模型的准确性；研究了 T 形流道在不同工况下的流动特性和冲蚀磨损特性；根据不同结构参数和边界条件的模拟结果，采用响应面法对 T 形流道的冲蚀磨损进行了预测和计算，得到了最大冲蚀率的预测公式。通过该公式可快速确定优化的流道结构参数，以减少侵蚀磨损对阀门造成的损坏。该工作可快速预测阀笼关键部位的冲蚀磨损率，为 CSCV 的寿命预测和结构优化提供一定的参考价值，同时也有利于煤制油系统的安全和维护。
{"title":"Erosion Wear Analysis On Valve Cage of Cage-Typed Sleeve Control Valve for Coal Liquefaction","authors":"An-qi Guan, Feng-ping Zhong, Chang Qiu, Zhi-jiang Jin, J. Qian","doi":"10.1115/1.4065306","DOIUrl":"https://doi.org/10.1115/1.4065306","url":null,"abstract":"\u0000 Cage-typed sleeve control valve (CSCV) is the key basic equipment in direct coal liquefaction project. The working condition of CSCV has the characteristics of high pressure difference, high velocity and high solid content. There is a general problem of liquid-solid two-phase erosion wear in CSCV, which is easy to lead to the failure of internal structure in the valve cage. Therefore, it is necessary to study erosion wear characteristics of internal structure in the valve cage. Based on the actual situation of erosion wear in the valve cage, the simplified T-shaped flow path is designed, and the accuracy of the liquid-solid two-phase flow model and the erosion prediction model are verified; The flow characteristics and erosion wear characteristics of T-shaped flow path under different working conditions are studied; Based on the simulation results of different structural parameters and boundary conditions, the erosion wear of T-shaped flow path is predicted and calculated by response surface method, and the prediction formula of maximum erosion rate is obtained. The formula allows for the rapid determination of optimized flow path structural parameters to reduce damage to the valve from erosion and wear. This work can quickly predict the erosion wear rate of the key areas in the valve cage, which can provide a certain reference value for the life prediction and structural optimization of CSCV, and it can also benefit safety and maintenance of coal liquefaction system.","PeriodicalId":504378,"journal":{"name":"Journal of Fluids Engineering","volume":"7 5","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-04-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140708945","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}
京公网安备 11010802042870号
京ICP备2023020795号-1
扫码关注我们
求助内容：
应助结果提醒方式：