Aerodynamic Performance of an Air-Cooled Redial Turbine : Cold-Air Testing and Performance Calculation of a Radial Turbine with Air-Cooled Nozzles

A cold-air study of an air cooled radial turbine was carried out to find out the effect on the aerodynamic performance of the coolant-air ejection from the pressure surface of the nozzle blades. The testing of the investigation was conducted at pressure rations of 1.5, 2.0 and 2.5 and over a range of coolant-air to primary-air mass flow percentages from zero to six percentages. The rations of coolant-air to primary-air temperature were from 0.7 to 0.8. Two calculation methods of the performance of the air-cooled radial turbine were proposed. One of them needs data of a noncooled radial turbine performanse ; the other does not need them. Both calculations are able to predict well the performance.