Experimental and Numerical Investigation of Tip Leakage Flow in a 1 1/2 Stage Turbine Rig Comparing Flat and Cavity-Squealer Tip Geometries

Tip leakage loss is one of the main loss mechanisms in shroudless high-pressure turbines. Efficiency reducing phenomena are the reduction of mass turned by the blade, and the mixing of the tip leakage and passage flow. Applying a cavity squealer tip is a promising technique to reduce the tip leakage loss. The study investigates the influence of a cavity squealer on the flow field of a 3D high-pressure turbine.The 1 1/2 stage turbine test rig is equipped with steady and unsteady measurement techniques, like five-hole probe, 2-component hot wire, oil & dye visualization, unsteady wall pressure probes and particle-image-velocimetry measurements. To improve the flow phenomena interpretation, unsteady numerical simulations were carried out using a commercial solver.Copyright © 2012 by ASME