Experimental analysis of the unsteady pressure field induced by a simplified geometry of the suction elbow at the pump inlet

The actual conditions imposed by the energy market require to storage energy when the energy cost is cheap. The storage pumps (double flux or multistage pumps) are structurally different from the regular ones. As a particularity, these types of pumps are equipped with a suction elbow with complex geometrical configuration. The suction elbow generates unsteady hydrodynamic phenomena, which are ingested by the impeller, leading to severe structural and cavitational issues. A suction elbow with a simplified geometry is experimentally investigated to assess the unsteady field at the pump inlet. The unsteady pressure signals acquired on both inlet and outlet walls of the suction elbow are analyzed for nine discharge values from 16.6 l/s to 43.7 l/s. The maximum amplitudes are identified on the power spectra corresponding to the largest discharge values. Both plunging and rotating components are discriminated in each cross section. The plunging component is dominant underling that the interaction of the flow with the suction elbow is the main cause of the unsteady phenomena.