Pneumatic Catapult Performance Research Based on the True Thermodynamic Process Analysis

Abstract

In the high-pressure pneumatic thermodynamic process, the pressure is much larger than the critical pressure,and the temperature deviates from the Boyle temperature seriously, the thermodynamic parameters are not authenticity under ideal gas assumption, so pneumatic performance of the quality can not be guaranteed. In view of this, the pneumatic equations are estabalised on the basis of modified corresponding state equation and improved virial equation for the high-pressure air catapult launch system, and the real dynamic thermodynamic processes are analyzed. The specific residual thermodynamic parameters of high pressure air are presented, the real thermal physical property parameters are also obtained under the wide variation conditions of temperature and pressure. The residual functions are applied to compensate the uncertainties of thermal physical property parameters, numerical experiments are performed. The comparison of the numerical results show that the value of residual enthalpy is high, the state of working fluid deviates from ideal gas; the compressibility of working fluid is strong, the compression factor reaches 1.101 3; the real gas effect accelerates the pressure and temperature decreasing rates in the hyperbaric pressure chamber, and decelerates the increasing rates in the low pressure chamber; the real work capability of hyperbaric air is lower than that of ideal gas, the overload is steady.