Experimental Study and Simulation of Cavitation Shedding in Diesel Engine Nozzle using Proper Orthogonal Decomposition and Large Eddy Simulation  

作　　者：HE Jiajun AN Qingsong JIN Jiangshan FENG Shuai ZHANG Kemu 

机构地区：[1]Key Laboratory of Medium-Low Temperature Thermal Energy Efficient Utilization of Ministry of Education,School of Mechanical Engineering,Tianjin University,Tianjin,300350,China [2]Shanghai Marine Diesel Engine Research Institute,Shanghai,201108,China

出　　处：《Journal of Thermal Science》2023年第4期1487-1500,共14页热科学学报（英文版）

基　　金：This work was supported by of the National Natural Science Foundation of China(No.50906041).

摘　　要：The unsteady cloud cavitation shedding in fuel nozzles greatly influences the flow characteristics and spray break-up of fuel,thereby causing erosion damage.With the application of high-pressure common rail systems in diesel engines,this phenomenon frequently occurs in the nozzle;however,cloud cavitation shedding frequency and its mechanism have yet to be studied in detail.In this study,a visualization experiment and proper orthogonal decomposition(POD)method were used to study the variations in the cavitation shedding frequency and analyze the cavitation flow structure in a 3 mm square nozzle.In addition,large eddy simulation(LES)was performed to explore the causes of cavitation shedding,and the relationship between cavitation and vortices.With the increase of the inlet and outlet pressure differences,and fuel temperatures,the degree of cavitation intensified and the frequency of cavitation cloud shedding gradually decreased.LES demonstrated the relationship between the vortices,and the development,shedding,and collapse of the cavitation clouds.Further,the re-entrant jet mechanism was found to be the main reason for the shedding of cavitation clouds.Through comparative experiments,the fluctuation of the vapor volume fraction in the nozzle hole accurately predicted the regions with stable cavitation,re-entrant jet,cavitation cloud shedding,and collapse.The frequency of cavitation shedding can then be calculated.This study employed an instantaneous POD method based on instantaneous cavitation images,which can distinguish the evolution process and characteristics of cavitation in the nozzle hole of diesel engines.

关 键 词：diesel engine proper orthogonal decomposition cavitation shedding cavitation collapse large eddy simulation 

分 类 号：TK421[动力工程及工程热物理—动力机械及工程]