Gas Foil Bearing: Effect of Foil Materials and Stability Analysis Using Different Models for Foil Structure

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Gas foil bearings (GFBs) are compliant surfaces, self-acting hydrodynamic bearings typically constructed from several layers of sheet metal foils. These foils rest on elastic support structure and their performance largely depends on this support structure. A commonly used such foil structure consists of bump strips and the smooth foil rest on top of these strips. The widespread usage of GFBs includes turbomachinery applications such as in turbo-generators, turbines, IC engines, compressors, pumps, light weight business aircraft engines etc. and a comprehensive numerical modelling verified with the available test data enables this usage. This work sets out a structured and formal approach for the steady state analysis and the stability analysis of GFBs by mounting on a rotor bearing system. A literature review is carried out to assess the state of the art regarding both theoretical and experimental studies about GFBs. Based on the review, an attempt has been made to study several aspects of GFBs as mentioned hereunder in brief. The compliant foil structure is modelled using the finite element method. Three different numerical models viz. Onedimensional (1D) beam element model, two-dimensional (2D) Classical Plate Theory (CPT) model and 2D Shear Deformation Theory (SDT) plate model were considered for modelling the compliant structure. The foil deflections calculated from the structural model using finite element analysis is coupled to the hydrodynamic gas film model governed by Reynolds equation to predict various characteristics of GFBs...
Supervisors: S. K. Kakoty and K. Kalita