External Heat Transfer Enhancement to Turbine Blading due to Surface Roughness

Abstract

This paper addresses the influence of surface roughness on the heat transfer to gas turbine blading. A survey of fifty eight industrial and aero-engine blades is reported which indicates the trends in surface roughness with service hours and operating environment. A detailed boundary layer roughness model, incorporating a low Reynolds Number k-ε turbulence model, is then presented. The model is calibrated with respect to the heat transfer measurements of Hosni et al (1989). Predictions are then made of the rough-blade heat transfer measurements of Turner et al (1985), which show that the increased heat load to the blading is reasonably well predicted by the proposed model.