Experiments on Transpiration Cooling: First Paper: Discrete Hole Injection as a Means of Transpiration Cooling; an Experimental Study

Abstract

Mean velocity and injectant concentration profiles are presented for the boundary layer on a flat plate with air injection through rows of discrete holes. An 8/1 pitch/diameter ratio was used. Three hole arrangements were studied in detail. For holes perpendicular to the surface, both in-line and staggered configurations were examined, while, for holes angled 45° downstream, only staggered holes were used. Some results are also presented for Freon injection and it is shown that this higher density injectant always gives higher concentrations at the wall. Angled injection is also shown to give improved cooling effectiveness.