An experimental investigation of a high radius pre-swirl cooling system

An experimental investigation into pre-swirl effectiveness and receiver hole discharge coefficient characteristics for a high radius injection pre-swirl cooling systems was carried out on a physically representative experimental rig with a 450 mm diameter rotor. The receiver holes and pre-swirl nozzle were located at a radius of 181 mm and 180 mm respectively. The experimental work was mainly conducted at 5000-12000 rpm, 4 bar absolute pressure and 1.132 kg/s air supply. The maximum air supply temperature was 190C. Pressure and temperature distributions in the pre-swirl system were examined with an emphasis on the velocity effectiveness of the pre-swirl system as a whole and on the discharge coefficients of the rotating 'receiver holes' in the rotor. The results showed that the velocity effectiveness increased with increasing swirl ratio resulting in reduced blade cooling flow temperature. Increasing the seal flow rate reduced the effectiveness. For the coefficient of discharge, it increased with increase in swirl ratio for most speeds. But the coefficient of discharge is also decrease when the increase of inner seal flow rate.