NPSHr scaling for centrifugal pumps
Type:
Presented during:
CEDA Dredging Days 2024
Authors:
E. de Hoog, J.M. in 't Veld, C.F. Hofstra and A.M. Talmon
Abstract
Experimental validation remains an essential component in the development of new centrifugal dredge pumps. Computational Fluid Dynamics (CFD) simulations are well equipped to make estimations on the pump head and pump efficiency. However, the prediction of a drop in head due to cavitation, defined as the Net Positive Suction Head Required (NPSH_r) criterion, is harder to simulate using CFD. Cavitation is one of the major limitations in hydraulic transport systems and occurrence needs to be avoided in a well-designed hydraulic transport system. The onset of cavitation is influenced by pump size, geometry, rotational speed, flow and inlet pressure as well as the fluid properties: density, viscosity and vapor pressure. In this paper NPSH_r properties are investigated on a laboratory scale, using 3D printed impellers. The use of 3D printing of impellers makes this method a cheap and fast way to iterate towards improved pump design. The results of the scaled laboratory experiments are compared with full scale field experiments. In order to assess laws to scale, NPSH_r properties for geometrically identical pumps, so that knowing flow, rotational speed, pump size, inlet pressure and vapor pressure are enough to predict NPSH_r conditions from lab scale tests.
Keywords: Cavitation, NPSH, hydraulic transport, centrifugal pump