A prediction procedure for pump performance during its normal and reverse flow operation is developed for centrifugal pumps with a vaneless diffuser by integrating empirical loss models and analytical equations.
Losses in centrifugal pumps stem from a number of sources. However, their exact calculation is not yet possible. Most of the loss theories are one dimensional and many of the performance prediction procedures reproduce the experimental data only in a narrow region in the neighbourhood of the best efficiency point. In the present study, improvements are made for the prediction to cover the entire range of operation.
To predict the complete performance of centrifugal pumps in general, it is essential to include the procedure for estimation of 'head slip' of the centrifugal impeller at various operating conditions. The past theory and correlations available for the head slip only concern the normal operation of the centrifugal pumps. In this study a concept of 'negative head slip' for centrifugal impellers during reverse flow opration has been presented.
For the normal flow operation, prediction results are in good agreement with experimental data, which are better than the prediction by commercial computer code. Particularly, the predictions for the reverse flow operation agree well with the trend of experimental data.
