Abstract:Due to the existence of sticky,there is friction between air and wall when air passes through narrow channel in air aerostatic lubrication system.This will cause air pressure dropping down and temperature change,and bring bad effects such as working face deformation,gas film stiffness decrease.In accuracy fields,the effect of temperature change should be taken into account,and when calculating the air temperature variation in the process of throttling,the Joule Thomson coefficient must be calculated firstly.Cubic equation of state and BWRS equation were used to obtain the Joule Thomson coefficient under different air supply temperature and air pressure.The results show that the calculation results of RK and SRK equations are approach; the calculation results of these equations have the same change tendency,that is the Joule Thomson coefficient are decreased with the increase of air temperature and air pressure,whereas the air supply temperature has greater influence than air pressure to Joule Thomson coefficient.