Film Cooled Small Turbine Blade Research. Volume II. Film Cooling Effectiveness at Simulated Turbine Conditions.

摘要

The overall study concerns an investigation on the cooling and aerodynamic problems associated with a high speed turbine cascade of small blade height for use on small gas turbines. The secondary flow behavior in turbines is presented in Vol. I and cooling aspects are presented in Vol. II. Vol. II reports on the first year efforts on the measurement of effectiveness of a film cooling system for a small turbine by injection through inclined holes. A short duration facility was used to provide isothermal wall data at flow conditions carefully selected to simulate those expected in an advanced turbine. Appropriate heat and mass transfer equations have been developed to illustrate the interpretation and usefulness of data obtained in this as yet relatively unconventional method. The measurements showed: that there are small increases in effectiveness for injection on convex surfaces compared to flat surfaces; a change in flow Reynolds number only slightly changes effectiveness; a lowering of the mainstream Mach number from 0.6 to 0.3 causes a sizable decrease in effectiveness; a pressure gradient, typical of that seen on a turbine also decreases considerably the effectiveness.