Performance of Foil Cylindrical Gas Seal under High Thermal Gradient Conditions

The heat transfer between the high-temperature gas and solid components is described using conjugate thermal coupling boundaries to accurately capture the transient heat conduction along the axial direction of the seal. The results show that a large temperature gradient induces pronounced non-uniform thermal deformation in both the rotor and the foil. When combined with the temperature dependent variation of gas properties, this leads to significant changes in the film thickness and pressure distribution at the sealing interface.

The non-uniform expansion at the high-temperature end locally reduces film thickness and increases gas pressure, while smaller deformation near the low-temperature end causes asymmetric flow and pressure fields. As heat transfer time increases, the axial temperature gradient of the rotor and foil gradually decreases, resulting in more uniform deformation, lower leakage rate, and greater gas film force. Within the range of parameters examined, the CFCGS exhibits superior sealing performance under high thermal gradient conditions when the flexibility coefficient ranges from 0.10 to 0.13 and the eccentricity ratio from 0.5 to 0.7.

These findings provide insights into the thermoelastic behavior and design optimization of compliant foil seals used in high-temperature turbomachinery applications.