A study of the stall control involved in the casing treatment of a centrifugal compressor with recessed guide vanes

The authors have conducted an accurate time-variant three-dimensional numerical simulation with respect to a new type casing treatment structure that can remarkably improve the stability margin of the original compressor. A detailed comparison and analysis was performed of the flow fields in the blade tip region of a centrifugal compressor with a solid-wall casing structure and recessed guide vane type of casing treatment structure. The meridian speed distribution inside the blade passages in the radial direction is also analyzed, thus revealing the diffusion stabilization mechanism of the casing treatment structure with recessed guide vanes. An analysis of the calculation results of casing treatment with recessed guide vanes of different parameters shows that the increase in the axial overlapping amount is favorable for improving the stability margin of the compressor but unfavorable for enhancing its efficiency. The decrease of the groove depth will somehow improve the stability margin of the compressor. The total pressure ratios at both the peak and the stall point, however, will be somewhat reduced.