Experimental investigation of the influence of the inlet duct configuration on the unstable operation of a single-stage centrifugal blower

Abstract

The article is devoted to the experimental investigation of the interactions between the amplitudes and frequencies of surge in a single-stage centrifugal blower and the configuration of its inlet duct. In this work, the term ‘configuration’ implies the combination of the following: the volume of the duct, the presence of the filter inside the duct and the inlet guide vane position. The high-response pressure measurements were performed at three points along the impeller shroud (inlet, middle, outlet) and at a single point downstream the volute outlet and then processed with the use of fast Fourier transform (FFT). The results of the measurements show that the response of the surging system to a change introduced into the duct’s configuration is complex. The closure of the inlet guide vane typically causes a drop in the amplitude and frequency of fluctuating pressure. The introduction of a filter body into the duct most often damps the amplitudes of fluctuations, but leaves the frequencies unaltered. The change of the duct’s volume controls the rate of this damping.