Large-Eddy Simulations of Inclined Jets in Crossflow with Different Holes

摘要

Film cooling is a key technology to improve the thermal performance of high-pressure turbines. The mixing of thecooling air and the main flow is inherently unsteady,but the unsteady flow physics of different cooling holes areseldom investigated. In the current study,the large-eddy simulation method is used to investigate inclined jets incrossflow via a cylindrical hole and a fan-shaped hole. The angle between the hole and the main flow is 35 deg,and theblowing ratio is 0.5,which are representative for film cooling. First,the results are analyzed in a traditional way usingcounter-rotational vortices based on the time-averaged results. Then,the instantaneous flowfield is presented. Themixing of the injected flow with the main flow is highly related to the unsteady coherent vortices. The results showedthat the instantaneous flowfield can provide a better explanation of the distribution of film-cooling effectiveness thanthe time-averaged flowfield. The effects of instantaneous vortices on the temperature distribution for different coolinghole geometry are discussed in detail.