International Journal of Thermal Sciences, Vol. 110, pp. 270-284, 2016, DOI: 10.1016/j.ijthermalsci.2016
AbstractThermo-hydrodynamic behaviour of bidirectional dry gas seals with trapezoidal shaped symmetric grooves is studied. A multi-physics model, coupling compressible laminar flow and heat transfer in both the fluid and the solid bodies is used in a multi-physics modelling environment. The multi-physics model also includes slip flow conditions, corresponding to relatively high Knudsen numbers, as well as the effect of asperity interactions on the opposing seal faces. A comparison of the seal performance under isothermal and thermal flow conditions shows the importance of including the thermal effects. The difference in the predicted opening force between isothermal and thermal model can exceed 2.5%, which is equivalent to a force of around 1kN. The importance of designing gas seals to operate at the minimum possible gap to reduce power losses as well as leakage from the contact is highlighted. However, it is shown that there exists a critical minimum gap, below which the power loss in the contact can abruptly increase due to asperity interactions, generating significantly increased operating temperatures. Relative depths at the triangular and middle trunk parts of the grooves ℎ Convection heat transfer coefficient ℎ , , ℎ , Convection heat transfer coefficient from outer rims of rotor and stator Thermal conductivity of the gas Thermal conductivity of seal ring material
Keywords
Gas temperature at the inlet (outer radius), , , Gas temperature near rotor and stator contact face surfaces Temperature of the solid wall in contact with sealing gas