Swirl Flow in Conical Diffusers

Five conical diffusers with different divergence angles were tested to clarify the influences of swirl on the pressure recovery coefficients. Pressure recovery coefficients of all diffusers were improved by swirl, and the highest coefficient was observed in an 8-deg diffuser when the flow had a moderate swirl. The flow patterns in the diffusers were examined at various conditions to clarify the relationship between the swirl and the pressure recovery coefficient.