Heat transfer characteristics in an internal coolant passage with crossflow-induced swirl, impingement and film cooling holes

The effects of Reynolds number and bleeding ratio on heat transfer of impingement target surface, bleeding-hole surface and impingement channel side surface were investigated in large-scaled test models for the cooling passages in gas turbine blade. A transient liquid crystal technique was used to measure the local heat transfer coefficients of inner surfaces of impingement channel. The results show that, on impingement channel inner surfaces, the main causation of high heat transfer coefficient is caused by the first, second and third impingement, respectively. The average heat transfer coefficient of impingement target surface is the highest on the same Reynolds number by the direct impingement. The average heat transfer coefficient of bleeding-hole surface is higher than channel side surface. The impingement and swirl play a primary role on the Nusselt number of the researched surfaces. The heat transfer was augmented distinctly with increase of Reynolds number. The bleeding ratio also affects the value and distributions of heat transfer coefficients of all inner surfaces.