Prediction of the Effect of Diffuser Width on the Diffusion Process in a Radial Vaneless Diffuser

The vaneless diffuser downstream of a centrifugal impeller is probably the simplest geometrical turbomachinery flow passage, that can be described by three parameters. However, the flow through it is as complex as in any complex geometrical passage. Generally to analyze the flow in any turbomachinery component, methods could range from simple one dimensional to 3-D Navier Stokes. One dimensional methods are extremely simple and fast, but have limited accuracy and do not give full information. On the other hand 3-D Navier Stokes solutions offer more detailed information about the flow but are slow and cumbersome to use. As a compromise the designer prefers the use of a 2D or 3D viscid and inviscid solutions. Using a viscous streamline code this paper examines the effect of the diffuser width on the diffusion process.