A Study on the Axially Curved Mixed-flow Vaneless Diffusers

From a view point of machine dimension, the axially curved mixed-flow diffuser has a large benefit compared with the purely conical of the radially curved mixed-flow diffuser. In the present study, the flow pattern and pressure recovery in the axially curved mixed-flow diffusers are experimentally examined and the results are compared with those of the purely conical diffusers. The pressure recovery factor and diffuser effectiveness of the axially curved diffuser were low compared with the purely conical diffuser, but the difference between them was small. By use of guide fences at the inner wall, the flow in the axially curved diffuser was rectified and a favorable performance was obtained.