Studies of Wake-Affected Heat Transfer arounda Leading Edge of Turbine Rotors. lst Report, Heat Transfer Augmentation by Incident Wakes.

Abstract

Detailed measurements are performed on time-averaged pressure and heat transfer distributions around a blunt body which is affected by periodically incoming wakes from the upstream moving bars. The blunt body is a test model of a front portion of a turbine blade in gas turbines and consists of a semicircular cylindrical leading edge and a flat plate afterbody. A wide range of steady and unsteady flow conditions, such as Reynolds numbers based on the diameter of the leading edge and the bar-passing Strouhal numbers, are investigated. The measurement of the surface pressure distribution, in conjunction with the corresponding numerical analysis by BEM (Boundary Element Method), reveals the existence of the separation bubble around the junction between the semicircular cylinder and the flat plate, which is emphasized especially in higher Reynolds number cases. The wake-affected heat transfer distributions indicated that the wake passing over the leading edge caused significant increase in heat transfer in that area, and such phenomena become more pronounced in the higher Strouhal number cases.