Research On Aerodynamic Design Methods Of A High Pressure Ratio Centrifugal Compressor

The centrifugal compressors are widely used in micro gas turbine, Turbo-shaft engine and auxiliary power unit, due to the merit of high pressure ratio,small size and simple structure. It is considered that the compressors whose pressure ratio is around 10 have the optimal thermodynamic efficiency and the application demand of this kind of high pressure ratio compressor is very urgent. This paper focused on the design method of a high pressure ratio centrifugal compressor and completed the design of a centrifugal compressor whose pressure ratio was set as 9.5 and mass flow was set as 1.95kg/s. The main work are summarized as follows:1. This paper studied on the preliminary design method of a centrifugal compressors. A new performance prediction method which combined the loss model and math model was proposed and a design program was written.2. Use BladeGen to model the blade of the impeller on basis of the preliminary design. The simulation result showed that the highest isentropic efficiency of the impeller can reach 86.7% and the corresponding pressure ratio was 11.7.3. The splitter blades and the swept blades was studied. It was found that splitter blade can improve the performance of the impeller. But the operating margin will decrease if the splitter blade number is too big. Forward swept blade can improve the design efficiency at the cost of operation margin. Back swept blade can broaden the operation margin. At the same time, the design efficiency will not change evidently.4. The match of the impeller and different type of radial diffusers was studied. Wedge diffuser has a better diffusion performance than the vane-less difruser. the wedge diffuser which has a contraction in the inlet can increase the isentropic efficiency by 2.7%.5. The bend of the flow channel and the axial diffuser was designed. The change rule of the flow angle and velocity field of the gas flow through the bend was studied.