Experimental Investigation on the Suppression of Diffuser Rotating Stall in a Centrifugal Pump Using Diffuser Vane Slits

The diffuser rotating stall (DRS) is one of the biggest problems in pumps because unstable flow and pressure fluctuations are induced and the pump operating range is severely limited. The objective of this research is to suppress pressure fluctuation by machining slits to the diffuser vanes and confirm the effect on pump characteristics. In the experiment, two kinds of vaned diffuser, with and without slits, were investigated and time history of static pressure in the two diffuser passages were measured. Then, the data processing of wave form was conducted by Fast Fourier Transform (FFT) analysis. The shaft rotating speed dependency on the instability phenomena, the amplitude of pressure fluctuation and the onset flow rate of DRS was summarized.