Investigations on the nonlinear deformation behaviour and sealing performance of spring-energised seal ring for a high-pressure oil-free compressor

Purpose This study aims to provide a stress-strain calculation model that considers nonlinear transient thermo-structural deformation to simulate the assembly and operation processes of a spring-energised seal ring. Design/methodology/approach The assembly process and working conditions of the seal ring, along with the transient deformation caused by friction between the sealing surface and the cylinder and the motion of the piston, are investigated. Based on the leakage model of the high-pressure multi-stage seal ring and nonlinear constitutive theory, a comparison between the spring-energised seal ring and a traditional multi-piece piston ring is performed. Findings Results reveal that the sealing performance and service life of the 4.4 mm seal ring are superior to those of the 3.3 mm ring, consistent with experimental findings. Piston motion significantly influences the leakage model, with leakage rates decreasing as the friction coefficient increases. However, as the roughness of the cylinder's inner surface increases, the leakage rate of the seal ring also increases. The spring-energised seal ring offers better sealing performance than the traditional multi-piece piston ring, although with a shorter service life. Originality/value This study proposes a novel approach for stress-strain calculations that accounts for nonlinear transient deformations. The stress-strain distribution and leakage rate of the sealing rings are comprehensively analysed, and the causes of sealing failure are identified.