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

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.

Automated summary

This study evaluated the impact of different forms of hot-streaks on the aerothermal performance of high pressure turbines using numerical simulations. The results showed that the interaction between secondary flows and hot-streaks significantly affected the rotor exit temperature, while the rotor surfaces were influenced by various complex secondary flows.