Numerical Investigation of the Load Distribution between the Main Blade and the Splitter Blade in a High-Loading Centrifugal Compressor

In the traditional design of the centrifugal compressor, the splitter blade and the main blade always keep the same shape. However, to enable high efficiency of the high-loading centrifugal compressor, the matching of design parameters of the splitter blade and the main blade needs to be optimized. In this paper, the influence of the load distribution between the main blade and the splitter blade on the aerodynamic performance, the flow field, and the internal vortices of a high-loading centrifugal compressor were studied by means of CFD prediction. Four cases with different values of the variable CR which is defined as the load-ratio of splitter blade to main blade were set up. In each case, the splitter blade and the main blade were shaped according to different laws of circulation distribution (rV_u) while the average circulation of the splitter blade and the main blade at any meridional position were consistent with that of the prototype. The results showed that a proper reduction of the load-ratio of splitter blade to main blade is beneficial to suppress the leakage vortex of the splitter blade and reduce the scale of the wake in the channel near the suction-side of the splitter blade, which consequently improves the flow uniformity at the impeller outlet and enhances the aerodynamic performance of both the stage and the component. The stage isentropic efficiency of the optimal case was found to be 0.7% higher than that of the prototype and the stage total pressure ratio was also improved. The optimal value of CR, which in this investigation is 94%, is supposed to be the result of the trade-off between the development of the wake and the leakage vortices in adjacent two channels. The optimization of the load distribution between the main blade and the splitter blade provides an opportunity to further improve the high-loading centrifugal compressor performance.