Aerodynamic and Heat Transfer Experimental Investigation of Platform Cooling on a HP Nozzle Vane Cascade

Abstract

The present paper reports on an experimental investigation carried out at Bergamo University Energy system and turbomachinery laboratory aiming to assess the aerodynamic and heat transfer performance of a high pressure nozzle vane cascade without and with platform cooling. Information collected from solid vane testing was used to design a first platform cooling scheme made of cylindrical holes. The cooling scheme was first aerodynamically tested to quantify its impact on secondary flows and related losses for variable injection condition. Heat transfer performances were then assessed through the measurement of the adiabatic film cooling effectiveness and of the convective heat transfer coefficient. From these data, the Net Heat Flux Reduction (NHFR) parameter was computed to critically assess the cooling scheme. The collected data set is significant for the design process, as it is useful for CFD validation and for the setting up of correlations. In particular, a MFR = 0.7% resulted to be the best injection condition for this geometry, being a compromise between aerodynamic loss augmentation, a good thermal protection inside of the passage and a limited heat load increase to the end wall.