Ultra-high-speed TEHL characteristics of T-groove face seal under supercritical CO2 condition

Abstract

Purpose The purpose of this paper is to acquire sealing properties of supercritical CO2 (S-CO2) T-groove seal under ultra-high-speed conditions by thermo-elastohydrodynamic lubrication (TEHL) analysis. Design/methodology/approach Considering the choked flow effect, the finite difference method is applied to solve the gas state equation, Reynolds equation and energy equation. The temperature, pressure and viscosity distributions of the lubricating film are analyzed, and sealing characteristics is also obtained. Findings The face distortions induced by increasing rotational speed leads to the convergent face seal gap. When the linear velocity of rotation exceeds 400 m/s, the maximum temperature difference of the sealing film is approximately 140 K, and the viscosity of CO2 is altered by 17.80%. Near the critical temperature point of CO2, while the seal temperature increases by 50 K, the opening force of the T-groove non-contact seal enhances by 20% and the leakage rate declines by 80%. Originality/value The TEHL characteristics of the T-groove non-contact seal are numerically analyzed under ultra-high-speed, considering the real gas effect and choked flow effect. In the supercritical conditions, the influence of rotational speed, seal temperature, seal pressure and film thickness on sealing performance and face distortions is analyzed.