Analysis On Cage Dynamic Characteristics And Strength Of Angular Contact Ball Bearing In Ultra-low Temperature Environment

In space delivery systems,liquid rocket engines fueled by liquid hydrogen and liquid oxygen occupy an important position in both commercial and military use,and the performance of turbo pump bearings working at ultra-low temperatures,high speeds and large loads will directly Affect the operation of the overall machinery.Turbine pump bearings usually use angular contact ball bearings.When working,the DN value exceeds 2×10~6,The complexity of the cage force is significantly increased.Serious failures such as cage instability or even fracture often occur.Therefore,the dynamic characteristics of the cage under ultra-low temperature Analysis and research on fluid-solid-thermal coupling are of great significance to solve the problems of bearing life extension and reliability under ultra-low temperature conditions.This paper considers the influence of ultra-low temperature and high speed on the cage deformation and radial clearance,establishes the nonlinear dynamic differential equation and dynamic analysis model of the turbo pump angular contact ball bearing,and analyzes the dynamic characteristics of the bearing cage with different structural parameters and operating parameters And the influence of bearing friction power consumption.Finally,considering the flow velocity and pressure of the cooling medium,a fluid-solid-thermal three-phase coupling model is established to analyze the temperature field and strength of the cage under ultra-low temperature environment.The main conclusions are:1.Due to the complex structure of the cage,it is difficult to accurately calculate the deformation of the cage using traditional theoretical formulas.The method of numerical simulation can be used to obtain the deformation of the cage under ultra-low temperature environments,and the numerical analysis method is verified by experiments reliability.2.For angular contact ball bearings,the shape of the cage pocket is elliptical under ultra-low temperature environment.The cage slip rate increases with the increase of bearing speed,radial clearance and pocket axial clearance;with the bearing load,guide clearance and cage circumferential clearance of the pocket increases and decreases.Bearing friction power consumption increases with the increase of bearing speed,axial load,guide clearance,pocket clearance and axial clearance;decreases with the increase of radial load and radial clearance.3.A fluid-solid-thermal three-phase coupled analysis model is established,and the fluid flow rate and fluid pressure at different inlet flow rates are analyzed.Then,considering the fluid temperature and bearing friction power consumption,the temperature field of the bearing cage is analyzed,and the maximum temperature of the cage is at the circumferential position of the pocket,and the temperature decreases with the increase of the fluid inlet flow rate.Finally,considering the impact of the fluid on the bearing and the influence of the temperature field on the cage,the strength of the cage is analyzed,and the maximum stress of the cage is at the axial position of the pocket,and as the inlet flow rate increases,the cage stress increases It is large,so the circumferential and axial size of the pocket should be reasonably designed when designing the cage structure.Due to the limitations of the current ultra-low temperature test conditions,it is difficult to directly conduct bearing bench tests under vacuum liquid hydrogen environment.The dynamic simulation model of the turbopump bearing established in this paper is based on the dynamic model of angular contact bearing at room temperature after considering the effect of ultra-low temperature on the bearing size.The simulation results of the turbo pump bearing indirectly verify the reliabilit y of the dynamic model established in this paper.The research results can provide a theoretical basis for the research and design of angular contact ball bearings for ultra-low temperature turbo pumps.