Numerical investigation of Thermo-aerodynamic characteristics of gas foil thrust bearing

Abstract

• Distribution of flow and temperature field in micro-clearance of GFTB are studied. • Temperature caused by viscosity dissipation accounts for more than 90% of aerodynamic heat. • The film temperature distribution is different when with or without viscous dissipation. • Temperature varies directly with rotate speed and inversely with film thickness. • Increase of wedge factor lowers the temperature and leads to reflux at the inlet. This study aims to reveal the thermo-aerodynamic characteristics of gas foil thrust bearings in the presence or absence of viscosity dissipation. The lubrication models in the cross-section of the gas film have been described, and the term of viscosity dissipation in energy equations is decoupled. The influence of different factors on gas film temperature distribution is discussed and compared. The results show when considering viscosity dissipation, the peak temperature is located near the circumferential outlet and the side of the outer diameter where has more shear stress. However, with the absence of viscosity dissipation, the peak value takes place near the end of the convergence channel where the gas compression is the most severe. Contrary to the case that without viscosity dissipation, gas film temperature decreases with the increase of wedge factor in the presence of viscosity dissipation. As wedge height increases, backflow will occur at the bearing entrance, reducing inlet temperature. When rotational speed increases, the gas film temperature caused by viscous dissipation increases much faster. The increase of film thickness reduces film temperature and bearing performance rapidly, but has no effect on the temperature distribution. This study confirmed that viscosity dissipation plays a significant role in the temperature rise and flow field of gas foil thrust bearings. More specially, temperature rise in the presence of viscosity dissipation accounts for more than 90% of the aerodynamic heat. The results obtained in this study are significant because they provide basic design guidelines for a temperature rise of the gas film.