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 an engine representative experimental rig with a 450 mm diameter rotor. The
receiver holes and pre-swirl nozzles were located at a radius of 181 mm and 180 mm respectively. The experimental work was conducted
at 5000-12000 rpm, 4 bar absolute pressure and 1.132 kg/s air supply. The maximum air supply temperature was 190ºC. 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. The
coefficient of discharge also decreased with an increase in inner seal flow rate.