INVESTIGATION OF THE INLET FILTER INFLUENCE ON UNSTEADY FLOW PHENOMENA IN A SINGLE-STAGE CENTRIFUGAL BLOWER

The instantaneous static pressure signal has been recorded alongside a single-stage centrifugal compressor impeller shroud tip and at the compressor outlet using four Kulite high-frequency transducers. The compressor inlet duct contained a cassette filter followed by a diagonal inlet guide. Such a design is typical for the machinery utilized for waste water aeration. The aim of the study was to check whether the filter might damp the pressure pulsations inside the compressor duct and thus decrease the unsteady aerodynamic loads on its elements. The signal analysis was held with the use of FFT-based procedure and the measurements were performed within the whole machine operational range. The experiments showed that filter disassembling caused a reasonable increase in pulsation amplitude during compressor unstable operation. The strength of the increase was found to be dependent on the inlet guide vanes setting angle. As for stable operational region, almost no differences were observed.