The proposed experimental investigation is concerned with the 2DPIV analysis of the unsteady velocity distribution inside the vaned diffuser of a radial pump at various flow rates. Some preliminary measurements reveal highly time-space periodic flow features near the design flow rate while new low frequency phenomena occur at low capacity. Both the phase averaged velocity and the cyclic unsteadiness distribution enlighten the shape and the momentum of the rotor wakes as they approach the diffuser blade leading edge, and they are transported downstream. Wakes downstream the impeller blades are the prevailing flow features in the diffuser at best efficiency point. At low flow rates the cyclic unsteadiness is hidden by non-periodic flow fluctuations and the phase averaged flow field is not representative of the flow features. Instantaneous PIV measurements allowed the large flow field unsteadiness to be evidenced, as related to the impeller passage.
UNSTEADY FLOW FIELD IN A RADIAL PUMP VANED DIFFUSER
SALA, ROBERTO
2009-01-01
Abstract
The proposed experimental investigation is concerned with the 2DPIV analysis of the unsteady velocity distribution inside the vaned diffuser of a radial pump at various flow rates. Some preliminary measurements reveal highly time-space periodic flow features near the design flow rate while new low frequency phenomena occur at low capacity. Both the phase averaged velocity and the cyclic unsteadiness distribution enlighten the shape and the momentum of the rotor wakes as they approach the diffuser blade leading edge, and they are transported downstream. Wakes downstream the impeller blades are the prevailing flow features in the diffuser at best efficiency point. At low flow rates the cyclic unsteadiness is hidden by non-periodic flow fluctuations and the phase averaged flow field is not representative of the flow features. Instantaneous PIV measurements allowed the large flow field unsteadiness to be evidenced, as related to the impeller passage.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
