Experimental determination of the fluctuating pressure on a rotating fan blade as a source of acoustic noise

Abstract

The fluctuating pressure on the rotating blades is a significant quantity responsible for the noise emitted from axial fans. In order to compute the noise from flow field data, a model is required which describes the fluctuations as a function of flow parameters. The paper presents the fluctuating pressure, measured on the rotating blade of a fan under different operating conditions. The turbulence intensity and the spectral density of the turbulent inflow velocity fluctuations are varied and measured. From CFD calculations quantities, such as boundary layer thickness, shape parameter, etc., of the flow around the blades are deduced and used as parameters. Simultaneously, the noise emitted from the fan is measured and compared to the fluctuating blade pressure.