Swirling Flow Through Annular Diffusers With Conical Walls

The performance of a series of diffusers of various lengths, area ratios and cant angles was determined experimentally over a range of inlet flow swirl angles between axial and 48 degrees. The results indicate that increases in the inlet swirl angle and the cant angle, particularly in combination, lead to increased distortion of the meridional velocity profile at the diffuser exit. With a swirling throughflow separation occurs at the inner wall and is encountered at progressively lower area ratios as the inlet swirl angle is increased. The tangential component of the flow is relatively independent of the meridional flow in that the angular momentum is essentially conserved and a high degree of similarity is found in these profiles at the diffuser exit.