Transport Mechanism of Hot Streaks and Wakes in a Turbine Cascade

摘要

This paper aims to understand the combined effects of upstream hot streaks and wakes on the blade-to-blade flowfields in a turbine cascade. The computational-fluid-dynamics method was first validated with the unsteady experimental results of the low-speed T106 cascade and then used to study more cases. To simulate the incoming hot streak, a parabolic temperature distribution was applied at the inlet of the computational domain. The incoming wake was simulated using a bar. Four cases with different relative phases between the hot streak and wake were investigated. In different cases, the hot streak and the wake interacted differently, which resulted in a different flowfield hi the downstream blade passage. The distributions of the perturbation velocity magnitude and the perturbation velocity vectors were used to explain different convection of the hot streak and the wake. The effects of the transport mechanism on the aerothermal performance of the cascade were discussed. It was found that the time-averaged blade surface pressure distribution and heat flux are similar for the cases studied. However, the fluctuation of the blade surface pressure distribution and heat flux differs significantly as a result of the different transport mechanisms.