Unsteady simulation of flow and heat transfer in a transonic turbine stage under non-uniform inlet conditions

Abstract

In modern aero-engines, the temperature non-uniformity (hot-streak) caused by the combustors and secondary flows caused by the rotor blades have a considerable impact on the aerothermal performances of the high pressure (HP) turbine. In this study, two idealized hot-streaks (radial and rounded) from literature and one engine representative hot-streak (distorted) were evaluated within a HP turbine stage using unsteady numerical simulation. The results were analyzed and discussed and they include, the stage performance, unsteady flow visualization, unsteady hot-streak transport, secondary flows/hot-streak interaction and blades thermal loading. It was found that the rotor passage had various complex secondary flows and the boundary layer on its surface undergone several transitions. The hot-streak transport and its contact with vane and rotor blades differed from one case to another. The secondary flows had a remarkable impact on the rotor exit temperature. They induced wavy shapes and corrugations of temperature gradients near the endwalls. All hot-streaks were completely deformed and distorted across the turbine stage. The rotor surfaces suffered from hot temperatures under radial and distorted hot-streaks compared with rounded hot-streak. Very high levels of the heat transfer were generated on the rotor suction side near the endwalls due to the vortices.