Effects of Size and Reynolds’ Number on Centrifugal Diffuser Performance

The use of non-conventional diffusing systems for centrifugal compressors has been mandated by the smaller diameter of many advanced turbofan engines. Optimizing the design of these geometrically complex diffusers by rotating component tests is both expensive and time-consuming. Methods of designing and static blow testing low-diameter, controlled-contour passage diffusers have been previously reported in which scaled-up models of six diffuser passages were constructed and tested at a Reynolds number comparable to that encountered in rotating component tests. One design was fabricated in full size and run in both a static blow test and a rotating component test. This paper reports on the performance of this design at several Reynolds numbers up to those encountered in engine application for several diffuser throat blockages. It is shown that as with geometrically simpler passages such as conical diffusers, static blow tests can also be used to optimize the design of geometrically more complex diffusing passages.