| Air is the refrigerant of air cycle refrigeration system which doesn’t pollute environment.Refrigerating systems has small volume and light weight,but its temperature range of refrigeration is very wide.So in recent years,air cycle refrigeration system has been booming at home and abroad.The turbine expander as the core equipment of air compression refrigeration cycle system,its performance has a decisive impact on entire refrigeration performance.Higher speed of the turbine expander can effectively reduce the volume and weight of chiller and increase the refrigeration capacity of chiller.Gas lubricated bearings with the advantage of low power consumption and high rotating speed just can meet the demand of rotor system of high speed turbine expander,so it has been widely used in the turbine expander.Protuberant foil hydrodynamic journal gas bearing is a new type of foil gas lubricated bearing.Compared with traditional rigid surface gas bearing,protuberant foil hydrodynamic journal gas bearing has higher load capacity,lower energy loss and better stability.Now studies on protuberant foil hydrodynamic journal gas bearing mainly concentrate on the aspect of experiment.Compared with experimental studies the theory studies are less,which lead to the condition that theoretical studies lag behind experimental studies.In order to better understand its lubricated mechanism,design and develop better performance of protuberant foil gas bearing,it’s necessary to conduct in-depth theoretical study.This paper first analyzes the theory of gas dynamic pressure,derive the Reynolds equation of gas film pressure distribution of gas journal bearing,and carries on the dimensionless for Reynolds equation.Used finite difference method discrete dimensionless Reynolds equation,finite difference equation of gas film pressure distribution is obtained.For the protuberant foil that a new type of support structure,the model of protuberant foil is established using finite element software named ANSYS Workbench.It is analyzed that how the protuberance height, protuberance radius and protuberant foil thickness affect the deformation of protuberance through forcing it.The couple method between pressure distribution and film distribution and SOR iterative method is used,the Reynolds equation and film thickness equation are solved by using MATLAB.The pressure distribution and thickness distribution of gas film and the load capacity of bearing are analyzed.By comparing with the experimental data, the method of this paper is reasonable and precise. The effect of shaft speed and eccentricity ratio on the static performance of bearing is analyzed.The support structure of protuberant foil has been optimized.The research results of this paper provide a theoretical guide for the promotion and application of protuberant foil hydrodynamic journal gas bearing,and lay the foundation for further research. |
PDF Full Text Request