Aerodynamic performance and noise characteristics of a centrifugal compressor with modified vaned diffusers

Abstract

Improvement of aerodynamic performance and reduction of interaction tone noise of a centrifugal compressor with vaned diffusers are discussed by experiments and visualization techniques using a colored oil-film method. The focus of the research is concentrated on the leading edge shape of diffuser vanes that are deeply related to the generation mechanism of the interaction tone noise. The compressor-radiated noise can be reduced by more than ten decibels by using modified diffuser vanes which have 3-D tapered shapes on both pressure and suction surfaces of the leading edge. Furthermore, by adopting the proposed modified diffuser vanes, the secondary flow which is considered to be an obstruction of diffuser pressure recovery can be suppressed, and also the pressure decrease observed in the throat part of the diffuser flow passage is reducible. Thus, the proposed diffuser vanes show a favorable result for both noise and the aerodynamic performance of the centrifugal compressor, and offer a few basic guidelines for the diffuser vane design.

Effects of tapered diffuser vane on the flow field and noise of a centrifugal compressor

“…10. pressure is suppressed and further pressure-rise characteristics can be acquired by using tapered diffuser vane type C. This effect has already been examined by a flow visualization technique using the oil-film method by the authors [5], and is considered to be caused by the secondary flow observed near the trailing edge of the vanes. However, this kind of secondary flow can not be seen near the trailing edge in the numerical results shown here.…”

“…Please refer to the previous paper [4,5] for further details of the tested compressor and tapered diffuser vanes.…”

“…The authors have already shown by experiments and also by flow visualization technique that the leading-edge shape of the diffuser vane may play an important role in both noise generation and compressor performance, and the tapered diffuser vanes which have three-dimensional tapered shapes on both the pressure and suction surfaces of the diffuser leading edge can reduce the noise level of the ITN effectively without any influence on the compressor performance [4,5].…”

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.…”