Geometrical transition properties of vortex cavitation and associated flow-choking characteristics in poppet valves  

作　　者：Liang LU Zhongdong LIANG Yuming LIU Zhipeng WANG Shohei RYU 

机构地区：[1]School of Mechanical Engineering,Tongji University,Shanghai 201804,China [2]Frontiers Science Center for Intelligent Autonomous Systems,Tongji University,Shanghai 201210,China [3]Technical Research Laboratory,Hitachi Construction Machinery Co.Ltd.,Tsuchiura 300-0013,Japan

出　　处：《Journal of Zhejiang University-Science A(Applied Physics & Engineering)》2024年第6期455-469,共15页浙江大学学报（英文版）A辑（应用物理与工程）

基　　金：supported by the National Natural Science Foundation of China(Nos.52075387 and 52375060);the Shanghai Natural Science Foundation of China(No.22ZR1464400);the National Key R&D Program of China(No.2019YFB2005102);the Shanghai Municipal Science and Technology Major Project(No.2021SHZDZX0100);the Fundamental Research Funds for the Central Universities(No.2022-1-ZD-04),China.

摘　　要：Poppet valves have become increasingly significant in ensuring precise digital flow rate and pressure control in hydraulic systems,necessitating a more profound understanding of the geometrical properties of cavitation in them,as well as associated flow-choking conditions.Through a comparative analysis with experimentally observed cavity images,we found that large eddy simulation(LES)turbulence modeling effectively replicates the geometrical properties of cavitation in these valves.The analysis demonstrated that cavitation is generated from vortices that result from the interaction between the notch contracta flow and the surrounding fluid structure.Variations in the internal or external vena contracta conditions result in fixed or discrete cavities,and the length-to-diameter ratio serves as a measure of the transition between internal and external vena contracta flow properties.This study establishes a threshold length-to-diameter ratio of approximately 2 for the tested poppet valves.More specifically,in notch structures with a smaller valve opening,longer sealing length,and smaller throttling angle(corresponding to a larger length-to-diameter ratio),the liquid-to-vapor transfer process is more evident than that in the reverse direction.A long-standing vapor cavity becomes fixed inside the notch,leading to a more pronounced flow-choking phenomenon.In contrast,for structures with a smaller length-to-diameter ratio,the cavitation process for discrete vapor cavities is more complete,ensuring fluid flow continuity and significantly reducing the occurrence of the flow-choking phenomenon.

关 键 词：Poppet valves Vena contracta Vortex flow Vapor cavity Flow-choking 

分 类 号：TH134[机械工程—机械制造及自动化]