Simulation Of Oil Splashing Lubrication Flow Field Of Overrunning Clutch And Optimization Of Key Lubrication Parameters

As an auxiliary transmission system component commonly used in aerospace and military industries,the overrunning clutch is characterized by complex structure,harsh working environment and high operating speed.In actual operation,using method of oil splashing lubrication,the clutch is sometimes in a state of lack of oil,which inevitably affects the stability and reliability of the wedges.In order to reveal the lubrication and wear characteristics of the overrunning clutch,slow down the wear rate of the key position and improve the service life,it is important to study the lubrication performance of the overrunning clutch in the oil splashing lubrication process.This paper takes a type of centrifugal release type overrunning clutch as the research object,establishes the numerical simulation model of overrunning clutch oil splashing lubrication process,explores the overrunning clutch oil splashing lubrication effect under different working conditions,and explores the influence of different input lubrication parameters on the overrunning clutch oil splashing lubrication effect and its sensitivity analysis,in order to provide a reference basis for extending the service life of key parts of the overrunning clutch and troubleshooting analysis.The main research contents and conclusions are as follows:(1)Introducing the types of overrunning clutches and the working principle of centrifugal disengagement type overrunning clutches;summarizing the current status of research on the dynamic characteristics and lubrication analysis of overrunning clutches in China and abroad and the existing problems.(2)Based on turbulent RNG k-ε model,gas-liquid two-phase flow VOF model and multiple reference system model for the characteristics of overrunning clutch,establishing the numerical simulation model of overrunning clutch oil splashing lubrication process.The original model of the overrunning clutch is simplified,meshed,the wall speed is set and the boundary conditions are pre-processed.It is the basis for the subsequent analysis and parameter optimization of the simulated oil splashing lubrication process.(3)Studying the overrunning clutch in the start-up,normal operation,windmill speed,air start condition splashing oil lubrication flow field and temperature field distribution law.The study shows that in the APU startup condition,the overrunning clutch oil quantity is relatively low,the lubricant flow rate is about 0.0529 kg/s,the wedges are not fully wrapped by the lubricant,and there is poor lubrication;In the normal operating condition of APU,the overrunning clutch oil volume is higher,the lubricant flow rate is about 0.0859 kg/s,the oil film on the wedges surface is obviously thickened,and the lubrication is good.In the windmill speed condition,the lubricant volume fraction increases with the increase of the outer ring speed;In the air start condition,the lubricant volume fraction decreases with the increase of the outer ring speed.(4)Studying the effect of lubricating oil circuit structure and lubricating oil parameters on the lubrication of overrunning clutch oil splashing.The volume fraction is used to quantitatively evaluate the effect of lubrication,and the study shows that: when the initial temperature of lubricating oil varies in the range of 40-120 ℃,the effect on the volume fraction of lubricating oil in the clutch is positively correlated.When the speed of each clutch component varies in the range of 2000-30,000 rpm,the effect on the volume fraction of lubricating oil is positively correlated.When the supply pressure is about 0.30 MPa,the volume fraction of lubricating oil is the largest.The volume fraction of lubricating oil is maximum when the oil supply pressure is about 0.30 MPa,and the trend of slightly decreasing will appear when the oil supply pressure continues to increase.The sensitivity of different oil splashing lubrication input parameters is compared,and it is found that the inner ring speed has the most sensitive effect on the oil splashing lubrication effect of the overrunning clutch,and finally an optimal combination of parameters is obtained.(5)Building an overrunning clutch oil splashing lubrication experimental platform.The temperature rise data was obtained by measuring the oil temperature before and after the lubricating oil,and compared with the theoretical local heat generation method and temperature field simulation distribution clouds to verify the validity of the simulation method and conclusions.This study can provide theoretical guidance for the lubrication design and manufacture of overrunning clutches,and also has some significance for the parameter optimization of overrunning clutch oil splashing lubrication.