An experimental investigation of a thick-aerofoil nozzle cascade

Abstract

The cascade tests on a thick-aerofoil turbine nozzle bla~te suitable for a cooled turbine show that it has a good performance over a wide incidence range up to M = 0.8. Above this value the loss coefficient rises and does not fall again as M = 1 is approached. Several methods of indication of the transition point have been tried and results show that the method depending on the evaporation of crystals gives a position inconsistent with three other methods, i.e., lamp-black deposit, surface total-head measurement and stethoscope search tube. The effect of the thick trailing edge on loss coefficient is almost that predicted assuming zero velocity behind the blade trailing edge. The heat-transfer increase due to transition is probably not large, and is no worse than that on a conventional turbine section.