Determination of the Efficiency of a Cooled HP Turbine in a Compression Tube Facility

The efficiency of a cooled transonic turbine stage was measured in a compression tube facility. The formulation takes into account mechanical losses, coolant flows and leakage flows. The proposed methodology allows computing the efficiency independently from the test rig. Owing to the short testing time (∼0.5 s), specific measurement and data reduction techniques are used. The paper details how the power, the overall mass flow, the mass-averaged inlet quantities and the stage pressure ratio are determined. The measurements of mechanical losses and of the thermodynamic properties of coolant and leakage flows are also described. Finally, results are presented and supported by an uncertainty analysis that identifies the random and systematic contributions to the final error.