Effect of pulsating injection and mainstream attack angle on film cooling performance of a gas turbine blade
Seyyed Mehdi Hosseini Baghdad Abadi, Saadat Zirak, Mehran Rajabi Zargarabadi
Abstract
Relatively few studies have examined the effects of pulsating unsteadiness in turbine cooling blades. This unsteadiness can be a result of compressor blades and vane interaction. In addition, there is a particular lack of data of full turbine blades at various angles of attack. The effects of pulsation frequency (f = 2 Hz, 50 Hz, and 100 Hz) and the angle of attack (α = 0°, 15°, and 30°) on the film cooling effectiveness of a row film jet at the leading edge of a modified NASA C3X blade for two blowing ratios (M = 0.5 and 1.0) in comparison with the steady state experimentally investigated on pressure and suction sides of the blade and the flow field are obtained by simulation. Three-dimensional transient Reynolds-averaged Navier–Stokes equations coupled with the shear stress transport turbulence model (SST k − ω) are used in this research. Square waves are considered to pulse the injection air. Results show that the distribution of the instantaneous film cooling effectiveness is affected by frequency, angle of attack, blowing ratio, and curvature of the blade. With an increase in the angle of attack and the pulsing frequency, the averaged film cooling effectiveness increased. Pulsation and angle of attack have different effects on the performance of the injection jet toward the pressure and suction sides of the blade. Mixing of injection air with the mainstream at the pressure side is more than that at the suction side. Under certain conditions, the averaged film cooling effectiveness of pulsation flow is greater than the steady jet.