Turbine Tip-Leakage Measurements

SPONSOR: Naval Air Warfare Center, Patuxent River, MD

As part of a project to quantify tip-leakage flow which account for 80% of the aerodynamic losses in turbines, LDV measurements have been performed in the endwall region of a new small annular turbine cascade. These measurements have quantified the effects of an aerodynamic window and established the minimum proximity to the endwall for LDV measurements. In addition to the annular cascade study, the Laboratory has obtained a Turbine Test Article for the Space Shuttle Main Engine/High Pressure Turbopump, which has being installed in the Turbine Test Rig. Performance tests have been completed on the first stage, and LDV measurements will be obtained in the endwall region of this turbine.

LCDR. Anderson continued the project by performing numerical predictions of the flowfield through the turbine using the NASA code SWIFT, which is capable of calculating multistage turbomachinery flows. He was also able to obtain a complete set of LDV measurements over the tips of the turbine rotor blades, at three axial station and at three radial depths. These measurements were taken through an aerodynamic window, which vented air from within the turbine to the outside. Failure of the quill shaft, which connected the turbine to the power absorbing dynamometer halted further tests. The quill shaft and dynamometer have been repaired and a follow on student is needed to continue the measurements through a pressurized aerodynamic window.