Measurement of the Periodic Flow Field in a Radial Diffuser Pump by the PIV-Method

Detailed flow measurements are conducted by two-dimensional Particle Image Velocimetry (PIV) in a low specific speed radial diffuser pump at the design operating point, in order to investigate the impeller-diffuser interaction. The measurements are conducted at midspan for different relative positions between the impeller and diffuser. The measuring region covers a complete impeller channel and also a complete diffuser channel. The analysis of the experimental results shows that a jet-wake structure is observed near the impeller outlet. The presence of the diffuser vanes mainly affects the impeller flow at the rear part near the impeller outlet. The diffuser flow strongly depends on the relative impeller position which provides different inflow conditions for the diffuser.