Theoretical Study Of Internal Meshing Rotary Positive Displacement Compressor-expander For Closed-loop Air Cooling Cycle

The consumption of the bleed gas sucked from engine and the system compensatory loss can bereduced by the employment of the closed-loop air cooling cycle in aircrafts. But the development of acompression–expansion hybrid machine with high efficiency and reliability is the key problem to thepractical application of the closed-loop air cooling cycle.A positive displacement compressor-expander, which is suitable for the closed-loop air coolingcycle, is constructed based on the internal meshing rotary mechanism with the merits of compactstructure, small vibration, and low noise. Especially, it is very convenient to form a two-stage ormulti-stage compression-expansion structure so as to further improve the performance of the closedair refrigeration cycle system.The objective of the present paper is to set up the relevant essential theories Firstly, themathematical description of rotor profiles and analysis of the meshing relationship between inner andouter rotors; then, the variation of working chambers’ volume related to the rotating angle iscalculated based on the line integral. Secondly, gas forces and torques acted on rotors, the drivingmoments on main shaft are analyzed Finally, a three-dimensional model of rotors is imported into adynamics simulation software, and the relevant constraints and loads are added to simulate thevariation of contact forces between meshing points, and the simulating result is compared with thetheoretical method.The results, can not only promote development of closed air cooling cycle, but also play animportant role to extend the application of the internal meshing rotary mechanism.