Pressure Measurements in the Blade Passages of a Radial Inflow Turbine

Abstract

Pressure measurements were carried out in an unshrouded radial inflow turbine in a closed circuit test facility, at nozzle inlet and exit, vis-a-vis rotor exit. Besides, blade surface pressures on the nozzle and rotor blades, wall static pressures on the back plate of nozzle and rotor blade passages, shroud static pressure variation along the casing from rotor inlet to exit were also measured for four different mass flows through the turbine. The increase of nozzle exit angle resulted in an increase of the stator loss coefficient at any mass flow rate. Rotor pressure measurements showed an adverse pressure gradient on the suction surface close to the hub region. Compared to the total pressure levels near the hub and shroud of the rotor passage, the pressure was higher at the mid height. The swirl at the rotor exit is somewhat stronger near the tip region as compared to the hub and the average loss is more towards the tip.