Proceedings of the Thirty-second (2022) International Ocean and Polar Engineering Conference
Shanghai, China, June 5–10, 2022
Copyright © 2022 by the International Society of Offshore and Polar Engineers (ISOPE)
ISBN 978-1-880653-81-4; ISSN 1098-6189

www.isope.org

Effects of Blade Leading Edge Shape on Hydraulic Performances of Dredge Pump Based on Model Test
Hai-fei Zhuang, Ming-ming Liu, Yong-ding Wu

CCCC National Engineer Research Center of Dredging Technology and Equipment CO.,TD
Shanghai, China

ABSTRACT .

Scholars from many domestic universities and scientific research
institutes have carried out numerical simulation and experimental
research on the design of centrifugal pump blades: The numericalsimulation method was used to analyze the influence of the position ofblade inlet edge on the performance of centrifugal pump. The results
show that the appropriate extension of blade inlet edge to the outlet
direction can improve the cavitation performance, but when the blade isextended too much, the head will be significantly reduced (Zhao, 2019);
The performances of centrifugal pumps with different blade inlet edges
were compared. The results show that the head and efficiency of theconcave shape at the blade inlet edge are significantly improved, andthe range of high efficiency zone is the widest (Li, 2019); The design ofthe dredge pump was optimized by combining the methods ofnumerical simulation and model test, which has improved theefficiency of the dredge pump (Zhuang, 2015). After the transformationof the dredge pump of 4500m3 trailing suction dredger "Hang Jun4006", the efficiency of the dredge pump has been increased from 60%
to 85%, and the energy saving and efficiency increase is very obvious(Zhuang, 2017). The cylindrical blade was modified into a threedimensional twisted blade, The productivity of dredger is increased byabout 34.1% in Shimen'ao dredging project in Putian, Fujian Province(Zhuang, 2020). A steady numerical study on the cavitation
performance of a six blade pump, and pointed out that the larger theparticle diameter and the larger the solid volume concentration, themore likely the sludge pump is to cavitation (Zhang, 2010); The anti
cavitation performance of centrifugal pump can be improved bychanging the shape of blade inlet edge, such as making the blade inletedge concave and thickening the blade inlet (Yan, 2015); The blade
inlet placement angle was increased to improve the anti cavitation
performance under high flow conditions (Zhang, 2003); Jiang (2017)
analyzed the influence of pump casing throat area on the cavitation
performance of centrifugal pump through numerical simulation. The
results show that properly increasing the pump casing throat area canreduce the NPSHr; Wu (1995) tested and analyzed the influence of theaxial projection shape of the impeller channel on the efficiency andcavitation of the centrifugal pump. The results show that appropriately
increasing the impeller inlet area can improve the cavitation
performance of the pump without significantly affecting the efficiency.
Zhang (2012) analyzed the influence of three kinds of blade inlet
thickness on the cavitation performance of centrifugal pump bynumerical simulation method. The results show that using the variation

Aiming at the impeller of trailing suction dredger, on the premise of thesame impeller dimensions, three kinds of twisted blades with inlet edge
shape were designed. The model pump was made according to theproportion of 1:2. The external characteristics and cavitation
performance tests were carried out on a high-precision open test bench,and the effects of three kinds of blade inlet edge shape on theperformance of the model pump were compared and analyzed. Whenthe flow rate is less than the design flow rate, the shape of the inlet edgeof the three blades has little influence on the external characteristics;
when the flow rate is greater than the design flow rate, the shape of thesuction port of the blade has a significant influence on the pump headand efficiency. For the cavitation performance, the shape of the suction
port of the blade has a great influence on the NPSHr of the pump. The
difference of NPSHr is up to 0.8m near the design flow rate. The
phenomenon of sudden drop of head in cavitation test is analyzed, andthe harm of this phenomenon to the slurry transported in the process ofdredging is pointed out. Small NPSH is as important as stable operation
at the critical cavitation point. By changing the shape of blade suction
port, although the efficiency of large flow is reduced, the anti cavitation
performance of dredging pump is significantly improved.

KEY WORDS:Trailing suction dredger; model test; dredger pump;blade inlet edge shape; cavitation.

INTRODUCTION
Trailing suction dredgers are widely used in reclaiming land from thesea, large deep-water ports and deep-water channel projects. With theapplication of intelligent and efficient dredging equipment, trailingsuction dredgers put forward higher requirements for the performanceof dredge pumps. For example, the dredging and loading of trailingsuction dredgers require better anti cavitation performance of dredge
pumps, improve dredging efficiency, and ensure that trailing suction
dredgers can still operate normally under large dredging depth. During
the construction of dredging vessels, the operating point of the dredge
pump also changes with the different soil quality and conveying
concentration. Characteristic of dredged soil, conveying concentration,
NPSHr and other factors will affect the construction output andefficiency (Xu, 2016, Li, 2015).

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