Noise reduction and surge margin improvement using tapered diffuser vane in a centrifugal compressor

Abstract

Improvement of surge margin and reduction of interaction tone noise radiated from a centrifugal compressor with a vaned diffuser is discussed from experiments and CFD analyses. Two types of one-side tapered diffuser vanes, which are shroud-and hub-side tapered vanes, were used in the experiments. The height of the leading edge of the tapered vanes varied from 100% to 10%. Both types of tapered vanes are effective for the reduction of the interaction tone noise radiated from the compressor, because of the smaller interaction area between impeller-discharge flow and diffuser vane surface. Especially, the hub-side tapered diffuser vane suppresses the evolution of the leading-edge vortex, which causes reverse-flow in the diffuser passage. Furthermore, the hub-side tapered diffuser vane, which has an optimized diffuser leading edge shape, can improve the compressor pressure-rise characteristics at low-flow operation and can enlarge the surge margin.

Effect of Centrifugal Compressor with Influence on Partial Vaned Diffuser

“…In the low-volume range, a hub vaned diffuser with a height-to-breadth ratio of 0.3 and a vaneless diffuser in the large-volume range gave higher mass-averaged static pressure coefficients [13]. While the pressure ratios rose at low rotational speeds, they decreased at high rotational speeds.…”

Noise reduction mechanisms for the inclined leading edge vaned diffuser in a centrifugal fan

“…A few studies have focused on the noise reduction of a centrifugal turbomachinery by optimizing the geometry of a diffuser leading edge. Ohta et al [9][10][11][12] proposed a tapered diffuser, in which the overall noise was reduced by 14.2 dB, and the performance of a centrifugal compressor was improved by up to 2.6%. Murakami et al 13 proposed a small groove located at a leading edge of a low-solidity diffuser in a centrifugal fan; the tonal noise was reduced by 5 dB, with no significant drop in the aerodynamic performance of the fan.…”

“…Ohta et al. 9–12 proposed a tapered diffuser, in which the overall noise was reduced by 14.2 dB, and the performance of a centrifugal compressor was improved by up to 2.6%. Murakami et al.…”