Flow Transition Phenomena and Heat Transfer Over the Pressure Surfaces of Gas Turbine Blades

Abstract

Detailed examination of flow measurements over concave pressure surfaces suggests that interaction of Taylor-Goertler vorticity with mainstream turbulence exerts only limited influence in enhancing laminar boundary-layer heat transfer. While transition is primarily controlled by the Launder laminarisation criterion, the Goertler number at which it subsequently occurs is not solely determined by turbulence intensity. Adoption of K≥2.5.10 – 6 as a design criterion for the pressure surfaces of turbine blades would appear to have significant advantages in terms of reduced heat transfer, increased lift, and lower aerodynamic drag.