Cavitation Research Of High-power Dredge Pump

Dredging pump is widely used in the desilting of rivers and lakes as well as the dredging and maintaining of river course. However, cavitation may occurred by certain factors when the dredging pump is working. When this happens, noises and vibration produced by the pump will largely reduce the working efficiency. What's worse, the pump could refuse working sometimes. Thus, searching for a way to improve the cavitation ability of the dredging pump is an important research area in fluid machinery.With the rapid development of computer performance and computer fluid dynamics, numerical simulation has become an indispensable way in designing dredging pump and analyzing its inner flow field. Numerical simulation can largely cut down the work load of testing, moreover, it can help pre-estimate the immeasurable data in testing so as to contract work hours and improve the reliability as well as the economical efficiency.This thesis is based on computer fluid dynamics and numerical simulation of the pump's inner flow field, which is carried out by means of business application software of CFD: FLUENT. The author adopts three typical working conditions: designing discharge Q₁ = 5000 m³/h, low discharge Q₂ = 3000 m³/h and high discharge Q₃ = 7000 m³/h. Meanwhile, two cases of mud concentration are adopted: 10% and 20%. Thus two cases are calculated respectively assuming that the diameter of the solid particle is 10mm or 20mm under a certain mud concentration. The following results can be found through analyzing the calculation: [1] The internal pressure of both the pump's inlet section and the volute casing is relatively high without cavitations. However, an obvious cavitation is occurred by the low pressure range, which is reduced in the latter part of the back of the front flange'vane in the impeller chamber. [2] Under high-discharge working condition, the square area of low pressure range and cavity volume range in the pump'impeller vane is far more larger than that of designing discharge and low discharge, which illustrates that the dredging pump is easy to be cavitated under high-discharge working condition. [3] By changing the mud contraction, the author finds that, in case the mud contraction is 10%, the square area of low pressure range and the cavity volume range in the pump'impeller vane is less than that in the case of 20%. [4] Under the condition of the same mud contraction, the author also finds that, in case the diameter of selected particle is 10mm, the square area of low pressure range and the cavity volume range in the pump'impeller vane is less than that in the case of 20mm.Finally, the author makes a conclusion of the affect aroused by different factors towards the dredging pump's performance and proposes revising plans and expectations.