EFFECT OF SWIRL INTENSITY ON HEAT TRANSFER CHARACTERISTICS OF SWIRLING FLAME IMPINGING ON A FLAT SURFACE

An experimental investigation has been carried out to determine the effect of swirl intensity on heat transfer characteristics of swirling flame impinging on a flat surface. The swirl intensity was varied by using helical vane swirlers having angles of 15 degrees, 30 degrees and 60 degrees (low, medium and high swirl). Qualitative flame structures were studied by taking direct photographs of impinging flames. Experiments were conducted for different helical vane swirlers at different dimensionless separation distances (H/d = 1-6) for fixed value of Reynolds number (Re = 5000) and equivalence ratio (phi = 1.0). A dip in heat flux was observed at stagnation point for all levels of swirl. Peak heat flux was observed slightly away from the stagnation point due to centrifugal effect. A comparison of stagnation point heat flux has been done for different swirl intensities and for fixed operating conditions. Most uniform heat flux distribution was obtained corresponds to 30 degrees helical vane swirler (medium swirl) at all separation distances.