Transient heat transfer and deformation characteristics of a bidirectional compressor cylinder block-piston assembly under multi-field coupling

Abstract

This paper established a multi-field coupling model for the air-cooled cylinder-piston assembly of a bidirectional compressor, proposed a transient calculation method, studied the temperature and deformation characteristics of each component in a single working cycle, constructed five evaluation indexes, analyzed the internal temperature and deformation characteristics of the cylinder block-piston assembly, explored the effect of different loads on the deformation, and verified the reasonableness of the method through tests. The results show that the research method of this paper is relatively accurate, and the calculation error is within 7 %; during a single working cycle, the temperature of each component shows a “W”-type change, and the maximum deformation shows a “folding” type change; the average temperature and maximum deformation of each component are highest at crank angles of 184° and lowest at crank angles of 101°; under extreme working conditions, the temperature and deformation of all parts are distributed in a “tilted” manner, with the percentage of the hot zones in the cylinder block as high as 54.6 %, and the thermal load plays a dominant role in the deformation of the cylinder-piston assembly; the average abnormal deformation at the position of support ring 1 reached 0.039 mm, which is very likely to cause wear and air leakage.