Direct and Reverse Flow Conditions in Radial Flow Hydraulic Turbomachines

Direct and reverse operation of radial flow turbomachines is examined. A runner momentum coefficient is defined which provides the means for correlating the ideal pump and turbine head-flow parameters in the region of optimum performance in both modes of operation. A theoretical procedure is thus arrived at by which turbine operation is predicted once the significant geometric parameters and the performance curves of a given pump are known. Tests on a number of machine configurations show that the results obtained at best efficiency operation by the present method are within ± 4 per cent of observed values, while errors in the predictions of empirical formulations may be more than ± 30 per cent. Furthermore, the present method gives a fairly accurate estimation of the range of flows for acceptable turbine operation, which is not considered by other procedures.