An experimental study of heat transfer in a simulated turbine blade cooling passage

Abstract

This paper describes an experimental investigation of heat transfer inside a simulated cooling channel for a gas turbine rotor blade. The channel is circular in cross-section and rotates about an axis which is orthogonal to its centre line. The study is aimed at the development of an experimental procedure and method of data processing which permits the determination of full axial and circumferential heat transfer data over the tube's inner surface. This is referred to as full field heat transfer data. In this respect a study of the combined effect of Coriolis and centripetal buoyancy forces on the forced convection mechanism inside the tube is the strategic aim. The experimental technique involved the determination of the inside surface temperature and heat flux distribution using a solution of the channel wall heat conduction equation. A series of wall temperature measurements on the leading and trailing edges of the channel, together with a prescribed electrically generated heat flux on the external surface, were used as boundary conditions with which to solve the channel wall heat conduction equation. The resulting internal heat flux distribution over the full inner surface was subsequently used to determine the local variation of heat transfer coefficient. The method was validated using data available in the technical literature and subsequently used to study the individual effects of Coriolis induced secondary flow and centripetal buoyancy using new data generated for the investigation.