ASME 1986 INTERNATIONAL GAS TURBINE CONFERENCE TRANSPIRATION COOLING: CONTRIBUTION OF FILM COOLING TO THE OVERALL COOLING EFFECTIVENESS.

Abstract

Future gas turbine combustion chambers and turbine blades require better cooling techniques to cope with the continual rise in operating temperatures with each new engine model. One technique that has been extensively investigated is that of transpiration cooling, for both combustion chambers and turbine blades. The authors are involved in an extensive investigation of full coverage discrete hole film or effusion cooling techniques which are aimed at achieving a performance close to that of transpiration cooling. It has been shown that the hole diameter and hence the effusion cooling pressure loss is of major importance in the overall cooling effectiveness. This effect is entirely due to the influence of the hole diameter on the film cooling performance as the internal wall cooling is reduced as the hole size is increased. A separate optimisation exercise has also been carried out on the impingement cooling geometry.