The influence of the impeller-cutwater interaction on the performance of a dredge pump
Type:
Presented during:
CEDA Dredging Days 2026
Authors:
S. Sapkota, T.J. Franken and B.P.M. Van Esch
Abstract
This study numerically investigates the effect of the cut-water distance on the performance of a dredge pump using computational fluid dynamics (CFD). The cut-water distance, defined as the distance between the impeller blade trailing edge and the volute tongue, significantly influences pump performance. Traditional methods for analyzing pump performance involve evaluating parameters such as hydraulic head, hydraulic power, shaft power, and efficiency. These parameters are intrinsically linked to hydraulic losses within the pump. Hydraulic loss, which encompasses energy dissipation caused by friction, flow separation, and turbulence, is often analyzed through pressure loss over specific pump sections. However, this method requires further post-processing steps to predict and quantify the locations of energy dissipation within the pump's flow domain. To address these limitations, this study adopts the entropy production theory, which provides a spatial distribution of energy dissipation sources and captures energy irreversibility caused by flow separation, turbulence, and friction. The entropy production method also verifies the hydraulic loss by comparing it to calculations made using the differential pressure method. By integrating the entropy production theory with the pump's overall performance parameters, this study evaluates the effect of cut-water distance on the entire pump domain, with particular focus on the near-tongue region. This approach enhances the understanding of energy dissipation mechanisms and offers a more comprehensive analysis of the pump's hydraulic performance.