Numerical analysis of the bifurcation point sensibility to the temperature field in the Taylor-Couette flow

Abstract

The flow between concentric cylinders, called Taylor-Couette flow, has been extensively studied during last century in works describing its governing parameters and presenting the various flow regimes for each configuration. This kind of flow is present in the air gap of electrical machines and its characteristics affect the heat transfer and the torque generated on the outer cylinder due viscous forces. The intensity of these effects depends on the flow state, which is governed by geometric characteristics and Reynolds number. Our objective is to analyze the effect of heat transfer on the surging wavy vortex and on the torque generated at outer cylinder. The numerical simulations are done using the software OpenFOAM v9 with K-Omega SST as the main turbulence model. All the simulations were in the transient regime. The pisoFoam solver was employed for the isothermal problem and for the buoyantPimpleFoam solver for the thermal problem. A mesh independence study was done based on Grid Convergence Index (GCI) method, where we found satisfactory values. For the thermal cases, we analyzed the behavior of the flow as we increase the Reynolds number and the temperature at the walls, comparing its results with the isothermal. It is notable the delay in the formation of the wavy vortices comparing with the rotational speed and the decrease of the torque on the external wall.