The paper reports on the flow field in a vaneless diffuser of a radial flow pump at partial flow conditions. Experimental data were obtained within the diffuser using 2D/3C high repetition rate PIV coupled with unsteady pressure transducers. The pressure measurements were acquired on the shroud wall of the vaneless diffuser and on the suction pipe of the pump. Pressure signals were investigated by frequency and time frequency analyses. PIV results were post processed using original averaging methods. Two partial flow rates were investigated in detail in this paper. Rotating instability occurred for both flow rates. A single instability mode was identified for the lowest flow rate whereas, for the higher one two competitive modes were recognized intermittently. Their spatiotemporal characteristics were described in the paper.
Rotating Instabilities in a Radial Vaneless Diffuser
CAVAZZINI, GIOVANNA;PAVESI, GIORGIO;ARDIZZON, GUIDO;
2010
Abstract
The paper reports on the flow field in a vaneless diffuser of a radial flow pump at partial flow conditions. Experimental data were obtained within the diffuser using 2D/3C high repetition rate PIV coupled with unsteady pressure transducers. The pressure measurements were acquired on the shroud wall of the vaneless diffuser and on the suction pipe of the pump. Pressure signals were investigated by frequency and time frequency analyses. PIV results were post processed using original averaging methods. Two partial flow rates were investigated in detail in this paper. Rotating instability occurred for both flow rates. A single instability mode was identified for the lowest flow rate whereas, for the higher one two competitive modes were recognized intermittently. Their spatiotemporal characteristics were described in the paper.Pubblicazioni consigliate
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