Development of a New-Style Micro Diffuser

Abstract

The vaned diffuser is advantageous in turbo-machinery which needs smaller size, so the vaned diffuser is widely used in the micro/small turbine engine. But the separation and strong mixing are often existent in the flow filed of such diffuser, and the viscous force, precision loss and frictional losses go up as size goes down, so the performance of micro diffuser is decreased. To improve the performance of diffuser in micro turbine engine, a new-style micro diffuser is presented in this investigation, which is composed of full blades and splitters. It is regarded as a series of ducts in design, and the effect of cross-section area distribution along the flow path on the new-style diffuser performance is studied. It not only can improve the performances, but also be easy to manufacture for micro turbine engines. The new-style micro diffuser was applied to replace the traditional vaned diffuser in an 11cm-diameter prototype engine, and the improvement of performance is verified by CFD and experiment. The advanced performance of the optimal micro diffuser (Cp above 0.65, σ above 0.9), is obtained with same external size.