Abstract
The formation mechanism of high thermal load at the blade tip plays an important role in effective cooling design and persistent operation of turbine blades. In this study, experimental investigation was conducted in a blow-down transonic wind tunnel to enable full optical access of a high-pressure turbine blade tip surface. Spatially resolved tip heat transfer coefficient was obtained for a flat tip by infrared transient thermal measurement. Combined with closely coupled unsteady self-adaptive turbulence eddy simulation numerical analysis, this paper first reveals alternating bands of high and low heat transfer coefficients (HTC) of the tip surface. Experimental data and computational fluid dynamics results consistently show this striped distribution of HTC, which indicates variations in the local heat transfer intensity. This phenomenon is linked to the formation of different types of vortices within the blade tip clearance. The clockwise (along flow direction) vortices originated from the detachment of the separation bubble, driven by the pressure gradient cross the clearance. As the clockwise vortices move cross the clearance, they induce low-energy fluid near the wall to form counterclockwise vortices, which alternate with the clockwise vortices in space. This alternating vortex pattern directly causes the high HTC stripes observed on the blade tip.
Published Version
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call