Abstract:
Accurate modeling of the compliant structure in gas foil thrust bearings is the key issue for predicting their Elastoaerodynamic performance. Hence, at the first part of this paper, a new structural stiffness model for the compliant structure in foil gas bearings is introduced. The model overcomes the shortcomings of previous analytical models and investigates the possibility that the flat segment between bumps, in bump foil strip, may deflect laterally and separate from the rigid bearing surface. Also, the interaction between bumps in the bump foil strip, the friction at bump foil/top foil interface, and the friction at bump foil/ rigid bearing interface are considered. The performance of the introduced analytical model with four different load distributions was analyzed and compared with previous numerical and analytical models so as to check the validity and flexibility of the presented model. In the second part of this paper, the introduced bump foil model is coupled to the compressible Reynolds equation to investigate the Elastoaerodynamic performance of Generation II gas foil thrust bearing. The numerical simulations of the coupled fluid-structure interactions revealed the fact that the foil thrust bearings share many features with their rigid bearings counterpart and it was found that the load carrying capacity of foil thrust bearings increases nonlinearly with the rotation speed. Also, the effect of ramp height on the load carrying capacity and friction torque were investigated.