The Use of Porosity to Simulate the Presence of Aerofoils on a Gas Turbine Shaft under Natural Cooling

摘要

After a gas turbine is shut down, internal buoyant convection during the cool down process can result in an asymmetric thermal condition on the compressor shaft. The resultant differential thermal expansion will cause the shaft to bow. In previous studies, the authors have used a combination of 3D conjugate heat transfer (CHT) computational fluid dynamics (CFD) and finite element analysis (FEA) to model the onset, duration, severity, and geometric distribution of the shaft thermal bow using simplified analogue models. This study investigates the use of porosity to simulate the presence of gas turbine compressor aerofoils for the purposes of modelling the onset of shaft thermal bow during the gas turbine static cooling process. The study then outlines a process for appropriate selection of the necessary parameters to describe a porous domain for use in a simplified gas turbine 3D CHT CFD model.