Measurement and analysis of three-dimensional flow in a centrifugal fan volute with large volute width and rectangular cross-section

Abstract

Among all the elements of a centrifugal fan, the volute is the one that has the lowest flow efficiency. Therefore, improving the performance of the volute is an efficient way to improve the total performance of a centrifugal fan. To contribute a better understanding of the flow structure in the fan volute, the three-dimensional flow in a centrifugal fan volute with a large volute width and rectangular cross-section has been measured in detail by means of five-hole probe at three different flowrates. The time-average swirling and throughflow velocity, static and total pressure distributions on eight cross-sections in the throughflow direction of the volute are presented. The results show the formation and development of the flow in the fan volute of this type, indicate the variation of flow parameters, and discover some peculiar flow phenomena different from the traditional understanding. On the basis of the experimental results, the main hydraulic losses in this kind of fan volute have been preliminarily classified and analysed. The results show that the traditional one-dimensional design method of the volute should be further improved as it is only based on the law of momentum moment conservation and the ideal assumption that the distribution of flow parameters are uniform at the volute inlet.

Volute characteristics of centrifugal fan based on dynamic moment correction method

“…Fan noise can generally be reduced by increasing the spiral line of the volute or enlarging the blade-tongue gap, which diminishes the fluiddynamic loading on the volute and the magnitude of tonal noise. 1,2 The pressure pulsation due to the flow impact of the volute tongue through the impeller-exit and the source region can be easily diagnosed. 3 Correct matching of the impeller and volute plays an important role in the centrifugal fan design process.…”

Design of volute shape of centrifugal fans

“…1 The efficiency of volutes, however, is the lowest among all components of the centrifugal fan. 2 Dawes 3 pointed out the fact that almost two-thirds of the energy losses occurred in the diffuser of the centrifugal compressor.…”

Experimental and numerical study on the inlet nozzle of a small squirrel-cage fan

“…3 However, many investigations have observed that the actual flow at the impeller inlet is non-uniform and the flow in each flow passage is different due to the asymmetric volute geometry, which induces the pressure grades along the circumferential direction. [4][5][6][7][8] The above impeller-volute interaction is an important cause of the flow separation and the reversed flow in the flow passage, and it also increases the flow loss and the noise level. Many research works indicate that improving the inlet condition of the impeller is an effective way to reduce the noise of fans.…”