CFD Simulation and Scale Model Testing of a New Dredge Pump Design
Type:
Presented during:
WODCON XXII - Enhance the Harmony between Dredging and Ecology
Authors:
R. Visintainer, J. Furlan, G. McCall, P. Springer
Abstract
"Computational Fluid Dynamics (CFD) simulations and laboratory model testing have been performed in connection with a centrifugal pump hydraulic design recently developed for cutter suction and hopper dredge service having an 1100 mm discharge, 1250 mm suction and 2540 mm impeller diameter. High fidelity, full machine, transient CFD simulations are described which accurately predict head and efficiency performance over a wide range of duties. A polyhedral mesh with prism layer wall elements and cell counts in excess of 24 million were used to model the entire wetted geometry, including suction and hub side gaps. This enabled a total hydraulic efficiency prediction by integrating shear stress and pressure fields over the entire surface of the impeller, internal and external. Pump performance was experimentally validated by the testing of two pure-scale model pumps having size ratios of 0.25 and 0.57, relative to the full-size design. Testing was carried out in the KSB/GIW Minerals Hydraulic Lab, and the test impellers were manufactured by rapid prototyping methods for maximum dimensional accuracy. In addition to comparisons with the CFD simulations, results from the two different model pump sizes of identical geometry were used to evaluate the accuracy of traditional pump scaling laws when applied to heavy section, large sphere clearance, dredge impeller designs. In a final step, a CFD methodology was developed to improve the NPSHR performance of the design without sacrificing efficiency or head. A third model pump was produced and tested to validate the result. High efficiency and low NPSHR were achieved in a three vane impeller design with a sphere clearance of 534 mm."
Keywords: Dredge pump, Centrifugal pump CFD, Pump scaling, Pump model testing, NPSHR improvement