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 (1–5) and turbine blades (6–9). However, most porous metal materials used in transpiration cooling are not adequate for gas turbine long life operation. Consequently, there is a requirement for simple, stronger and more reliable cooling techniques. Two similar materials developed for engineering reliability and transpiration characteristics are Lamilloy developed by Detroit Diesel Allison (10,11) and Transply developed by Rolls Royce (12). These materials both have full coverage discrete inlet and outlet holes but with internal passages within the wall connecting the two holes. Special manufacturing facilities exist to produce the complex geometries with metal thickness similar to current aero engine practice. However, these materials are not commercially available, are made in a limited range of designs and have large temperature gradients which may affect their life (10,11).