离心泵叶片布置凸起抑制空化的数值模拟

Numerical simulation of blade surface-fitted convex structure in centrifugal pump on cavitation suppression

提出一种在叶片工作面布置凸起结构抑制空化发展的方法.选用比转速为32的离心泵作为研究对象,应用剪切应力输运(SST)k-ω湍流模型和Zwart空化模型模拟非定常空化流动,并进行外特性实验.结果表明:计算结果与实验结果符合较好;布置凸起结构后扬程和效率小幅下降,扬程下降在1.5%以内,效率下降在1%以内;凸起结构改变了叶片表面粗糙度,减弱了叶轮流道内近壁面湍动能,有效减少了空化区面积,抑制了空化的发展;布置凸起结构后离心泵内空泡体积明显减少,最大减少量为57.9%;布置凸起结构后叶轮流道内压力脉动主频幅值明显缩小,说明凸起结构对空化诱发的振动、噪声和磨损等也有一定的抑制效果.

A method that convex structure was attached to the pressure surfaces of blades was proposed to suppress cavitation development.A centrifugal pump with the specific speed of 32 was selected as the physical model.Shear stress transport(SST) k-ωturbulence model and the Zwart cavitation model were employed to simulate the unsteady cavitation flow in the centrifugal pump,and external characterization experiments were performed. Results show that the numerical simulated results are in a good agreement with the experimental results.After the convex structure is arranged,the head decreases within 1.5%,and the efficiency drops within 1%.While the convex structure changes the surface roughness of the blade,weakens the intensity of turbulent kinetic energy near the wall in the impeller passages, effectively reduces the distribution of cavitation bubble, and thus controls the development of cavitation.The cavity volume in the centrifugal pump is significantly reduced after the convex structure is arranged,and the maximum fraction reduction is 57.9%. After the convex structure is arranged, the amplitude of the main frequency of the pressure pulsation in the impeller channel is significantly reduced, showing a certain suppression on vibration, noise and wear caused by cavitation.