FILM-COOLING OF THE GAS-TURBINE ENDWALL BY DISCRETE-HOLE INJECTION

Film cooling performance for injection through discrete holes in the e ndwall of a turbine blade is investigated. The effectiveness is measur ed at 60 locations in the region covered by injection. Three nominal b lowing rates, two density ratios, and two approaching flow Reynolds nu mbers are examined. Analysis of the data reveals that even 60 location s are insufficient for the determination of the field of film cooling effectiveness with its strong local variations. Visualization of the t races of the coolant jets on the endwall surface, using ammonium-diazo -paper, provides useful qualitative information for the interpretation of the measurements, revealing the paths and interaction of the jets, which change with blowing rate and density ratio.