Contouring effects on the adiabatic effectiveness distribution over a film cooled end wall cascade

The present paper investigates the effects of endwall contouring on the thermal performance of a nozzle vane cascade with endwall film cooling. The cooling scheme consists of four rows of cylindrical holes. Tests have been carried out at low speed (M2is=0.2) and low inlet turbulence intensity level (1%), with a coolant to mainstream massflow ratio variable in the range 0.5-2.5%. The influence of endwall contouring on the coolant protection capabilities has been studied through the measurement of the adiabatic film cooling effectiveness by means of the wide banded thermocromic liquid crystal technique. A particular attention was devoted to the TLC calibration, in order to take into account for the influence of contoured endwall surface curvature. Local, laterally averaged and area averaged adiabatic effectiveness distributions for variable injection conditions are compared against flat endwall data. A reduction in the area averaged effectiveness was observed for most of the injection conditions, mainly resulting from a lack of effective cooling in the vane front passage.