Aerodynamic measurements over a film cooled nozzle vane endwall

The present paper investigates the effect of endwall film cooling through discrete holes on the aerodynamic performance of a nozzle vane cascade. Experiments were performed on a simplified endwall cooling geometry operated at low Mach number (M=0.2), with holes located both upstream and downstream of the leading edge, varying the coolant to mainstream mass flow ratio. Secondary flow assessment with and without endwall film cooling was performed through flow visualizations and aerodynamic measurements. All these information allowed to draw a comprehensive picture of the complex aerodynamic flow field in the endwall region, enlightening the influence of endwall film cooling on the 3D flow field and secondary loss production. It was found that coolant injection strongly alter the secondary flow behaviour. A minimum loss has been found for injection rate MFR = 2.5%. The investigation of the effects of single row injection has shown that coolant injection upstream of the leading edge caused a lower secondary loss production, compared with those occurring in the rear part of the vane passage.