NUMERICAL INVESTIGATION OF THE EFFECT OF PULSED INJECTION ON FILM COOLING EFFECTIVENESS OF TURBINE BLADE UNDER ROTATION

Abstract

The effect of rotation on temperature distribution and film cooling effectiveness for turbine blade with sinusoidal and square pulsating coolant flow is numerically investigated. The RNG k−ε turbulent model is used to simulate the turbulence effects. Four rotation speeds of 0, 500, 800 and 1000 rpm are considered. Pulsed air coolant flow at three frequencies of 2, 50, and 500 Hz is injected to the turbine blade surface. It is to consider the combined effect of both rotation and pulsation parameters on film cooling performance simultaneously. The results show that pulsed film cooling effectiveness on pressure side and around the leading edge is reduced with increasing the rotational speed. On the suction side, with increasing rotational speed, film cooling effectiveness is decreased up to a distance of near the downstream of injection hole, but the behavior is reversed for further distances. In general, the pulsed film cooling effectiveness on the pressure side is greater than that on the suction side for different rotational speeds and frequencies. For sinusoidal and square pulsation, the deviation angle was almost the same but with increasing the rotational speed and pulsation frequency, the deflection increased. For various rotational speeds and frequencies, the film cooling effectiveness for sinusoidal injection flow is higher than for square wave flow.