Prediction of outlet flow characteristics of centrifugal impellers (1st report, Consideration of velocity distortion)

The analytical method of predicting the flow characteristics at the outlet of centifugal impellers is presented taking into account the influence of velocity distortion in both peripheral and the shroud-to-hub directions, and its effectiveness was confirmed with the measurements of flow characteristics around pump impellers. The results show that the increase of wall friction due to mixing of flow just after the impeller exit should be adequately considered to get successful prediction, and the influence of velocity distortion in the hub-to-shroud direction should also be considered for the case of parallel-walled channel width being larger than that of impeller exit, while it is negligible for the case of the channel width being equal to the latter. It is pointed out that the peripheral velocity component of the outlet absolute by the mass-averaged value of the determination of slip factor and theoretical head should be defined by the mass-averaged value of the section.