Thermo-fluid simulation of a rotating disc with radial cooling passages

Abstract

Turbine blade cooling via internal cooling channels is a very important aspect in modern-day gas turbine cycles. The need for blade cooling stems from the fact that higher cycle efficiencies requires higher maximum temperatures and therefore also higher turbine inlet temperatures. In order to evaluate the effects of these cooling flows on the cycle as a whole under various load conditions, it is necessary to simulate the compressible flow with heat transfer within the channels. The main objective of this study is to develop a mathematical model to simulate the steady-state compressible flow in the radial cooling channels of a simple rotating disc and to determine a temperature distribution in the disc. The disc's axis of rotation is vertical and it contains six equally spaced cooling channels through which air is dispersed radially outward. The steady-state compressible equations for the fluid flow in a rotating pipe were derived from first principals. The generated heat transfer in the rotating pipe was then coupled incrementally to a system of temperature conduction equations. It was then possible to determine a three dimensional temperature distribution in the rotating disc. The study also included an experimental validation of the flow model under adiabatic conditions. An inlet loss factor was empirically determined from data obtained from the experimental test bench. It was found that the inlet loss factor is a function of the inlet radial velocity component divided by the inlet tangential velocity component. Finally, it was shown that the results obtained from the theoretical model are in good agreement with the data obtained from the experimental test bench.