Time Resolved HWA Measurements of the OTL Flow Field From a Shrouded Turbine HP Rotor Blade

Abstract

Detailed time resolved Hot Wire Anemometry (HWA) measurement have been made of the over tip leakage (OTL) flow field, from a shrouded HP rotor blade. The objective of this study being to investigate the sensitivity of the flow conditions presented to the IP Nozzle Guide Vane (IPNGV), resulting from changes to the HP blade tip gap clearance and shroud geometry. An extensive experimental data set has been produced in the outer 25% of the annulus height. Post-processing of this data has allowed both the absolute & rotor relative velocity and whirl angle to be calculated, which has been presented in both a graphical and semi-animated form. A detailed analysis of the flow field has been undertaken, which has been compared with the exit flow field predicted by a comprehensive CFD simulation of the HP blade and shroud. Good agreement between the measured and the predicted flow field has been obtained. This has permitted the salient features, which influence the flow conditions presented to the IPNGV, to be identified. Advanced post-processing of the time-resolved data, has enabled some of the Reynolds and Deterministic stress components to be evaluated. A comparison of the magnitude of these components has been made, which the objective of assessing their relative importance in multistage steady CFD calculations.