Abstract: Instantaneous state analysis method is used to set up a mathematic model for compressed air engine, and fluid flow software Flowmaster flow software is used for research on the effect of parameters of compressed air system on performances for the engine. Through simulation, approach and method are brought out for increasing compressed air engine power performance and meliorate its economy performance. Research results indicate the following the pressure in the cylinder are increased by shortening up or down stream pipe length before or behind the inlet valve, and expanding upstream pipe diameter; The relation between downstream pipe diameter and charge quality is based on the Mach number in the downstream pipe of inlet valve; Indicative power is increased by expending exhaust valve diameter and adopting appropriate intake advance angle; Enhancing the pressure in the cylinder, improving the efficiency of intake air, increasing the indicative power are beneficial to improve power and economy performances for the compressed air engine.

Key words: Compressed air engine, Flowmaster flow software, Performance