Numerical study on impinging-film hybrid cooling effect with different geometries

The impinging-film cooling effect with different geometries was numerically investigated. Three major aspects including cross-sections of the inducting slab (rectangular or triangular), inducting channels (convergent, uniform and divergent) and jet inclinations (30°,45°,60°and 90°) are considered. The mass flow rate of the primary stream is 0.005 kg/s, the density flow ratio (DFR) ranges from 2.48 to 9.65. The results show that for all the cross section of inducting slab, the cooling performs better with an increase in DFR. For a constant DFR, triangular cross section shows 85.87% increased higher local cooling effectiveness, as compared with rectangular one. As DFR increases, however, the superiority of triangular cross section over the other becomes weak. The peak value of local cooling effectiveness improvement reduces to 11.53%. For the inducting channel optimization, it was seen that convergent channel can improve by 8.12% on the local cooling effectiveness while divergent one decreases by 16%. The jet inclination is found to have little effect on the cooling effectiveness, but plays an important role on determining the temperature distribution of the surface close to primary flow of inducting slab. The best performance was obtained with the inclination of 60°considering both liner and inducting slab.