Local Internal Impingement Heat Transfer Near a 30 and 90 Deg Row of Film Cooling Holes: Part 1 — Effect of Flow Parameters

Abstract

Experimental investigations of local impingement heat transfer characteristics near a row of film cooling holes in a simulated internal midchord region of gas turbine blade have been carried out. The research of heat transfer characteristics is focused on three film cooling hole diameter area located upstream and downstream a row of film holes. There is a line of equally spaced film cooling holes whose angles are 30 or 90 degrees. When there is no impingement, the investigation about the effect of the film cooling bleed has been carried out under different cross flow Reynolds Numbers and film outflow-to-crossflow mass flux ratios based on each film cooling hole/channel section area. The results indicate that the local heat transfer near the film cooling holes is enhanced with the increase of the crossflow Reynolds Numbers and film outflow-to-crossflow mass flux ratios based on each film cooling hole/channel-section area. The local heat transfer characteristic downstream film cooling holes is better than that upstream film cooling holes. The average Nusselt number of one time diameter area downstream the row of film holes is generally 40% more than that upstream the row of film cooling holes. The place closer to the hole will have stronger heat transfer whether upstream film cooling holes or downstream film cooling holes. When there is impingement, the impinging air is provided by a single line of equally spaced jets. The spacing of the jet holes is twice that of the film cooling holes with staggered arrangements. The local heat transfer near the row of film cooling holes has been studied experimentally through changing flow parameters, such as impinging Reynolds Numbers and mass flux ratios of crossflow-to-jet based on each channel/jet hole section area etc. A great number of experimental data has been obtained. Based on this, the effects of the flow parameters on the heat transfer characteristics have been obtained qualitatively and quantitatively. It can be the important reference for accurately designing gas turbine blade.