Thermo-Hydrodynamic Analysis of Low-Temperature Supercritical Helium Spiral-Grooved Face Seals: Large Ambient Temperature Gradient

Abstract

Hhighly efficient and reliable sealing technology is essential to improve the efficiency of precooled aeroengines. To explore the effects of large ambient temperature gradients on the sealing performance, the thermo-hydrodynamic characteristics of a supercritical helium spiral-grooved face seal were studied numerically, under low-temperature conditions. Considering the real gas effect of helium, the thermal deformations of the seal were analyzed numerically, under different temperature gradients. Additionally, the distributions of the pressure, temperature, and film thickness of the gas film were calculated, and the sealing performances of the seal under a wide range of working conditions were evaluated simultaneously. Results showed that a turning point occurred at the sealing pressure of 1.6 MPa in both the dynamic pressure effect and temperature rise of the gas film under the ambient-temperature gradient, leading to the transformation of the sealing gap, from convergent to divergent. The temperature gradient contributed to decreasing the thermal deformation and improving the sealing performance of the face seal. As the temperature gradient increased, although a mutational phenomenon existed near the sealing temperature of 250 K with both the dynamic pressure effect and the temperature rise, the variation of the opening force was within 120 N and the leakage was more than halved, indicating the broad application prospects of gas face seals in precooled aeroengine systems.