Development of a physics-based model to predict the performance of pumps as turbines (PATs)

This paper presents the development of a physics-based simulation model, aimed at predicting the performance curves of pumps as turbines (PATs) on the basis of the performance curves of the respective pump. The simulation model implements the equations to be used for the estimation of head, power and efficiency for reverse operation. In particular, its calibration on a given machine is performed by using loss coefficients and specific parameters. The tuning parameters are identified by means of an optimization procedure, which is first applied to pumps and subsequently to PATs. The simulation model is calibrated on literature data, reporting both pump and PAT performance curves for head, power and efficiency over the entire range of operation. The performance data were acquired experimentally on four different turbomachines, running in both pump and PAT mode and characterized by specific speed values in the range 1.53 - 5.82. The reliability of the predictions of the physics-based simulation model is quantitatively assessed against both pump and PAT experimental performance curves. Prediction consistency from a physical point of view is also evaluated.