Measurements of Fast Transitions at a Reversible Pump Turbine Model in Closed Loop Test Rig

Abstract

It is common practice to experimentally investigate the performance characteristics of hydraulic fluid machinery in power plants with steady-state operating points by scaled homologous model machines in closed-loop test rigs. In this case, the piping of the main water conduit from the power plant and the test rig plays a minor role. However, for studies of operating transient, e.g. load rejection, the influence of the weak compressibility of water in the pipes is considered by 1-D water hammer analyses. Due to differences in the main water conduit between the power plant and the test rig, the test rig is specifically controlled by new procedures to replicate the relevant conditions at the fluid machine in the test rig under similarity conditions.The results of this newly developed method for specific control of the test rig for operating transients are presented and successfully validated on a closed-loop experimental system. In future, suitable instrumented model machines then allow the measurement of dynamic pressures or even strains in and on machine components in order to elaborate, as a goal, the influence of different operating transients on the service life of machine components. Furthermore, these experimental data can also be used to validate Computational Fluid Dynamics (CFD) and Finite Element Analyses (FEA) simulations.