Experimental and Numerical Study of Cooling Gas Injection in Laminar Supersonic Flow

摘要

In this study, we investigate film cooling on an inclined flat plate in a laminar supersonic flow. The influence of the most relevant parameters, the Mach and Reynolds numbers of the freestream, the blowing ratio, and the blowing geometry, is examined using numerical simulations and in experiments. Importantly, a correlation factor that describes the effect of the most important parameters for a large range of flow conditions has been developed from a simple heat balance model. Unlike the results for turbulent conditions that are typical for cooling turbine blades, interestingly, we have found that considerably less cooling gas mass flows are needed to cool the surface over a large area. In laminar boundary layers no turbulence appears, so that neither the cooling gas strongly mixes with the main stream nor does the blowing momentum influence the cooling effectiveness, provided that a boundary-layer transition is not induced by the cooling gas injection. Our results, presented here, agree with the results of previous investigations of laminar supersonic flow conditions.