基于DDES的离心泵蜗壳内部涡动力学研究

为研究离心泵蜗壳内部涡结构、涡演化的过程，基于DDES湍流模型和涡动力学的涡量对离心泵多工况下的旋涡运动进行非定常数值模拟。研究表明:对比外特性数值预测和试验数据，两者差值在允许的范围内，表明延迟分离涡方法的可靠性；对比涡量云图，DDES湍流模型较RNGk-ε湍流模型能清晰地看到由大旋涡破裂而成的小旋涡，能更好地模拟精细流场结构；蜗壳内的旋涡主要集中在进口和隔舌附近，旋涡随着流体一起运动，在运动的过程中，大旋涡破裂为许多小旋涡，同时涡量逐渐减小；随着流量的增加，流道内旋涡的分布范围逐渐减少，同时涡量也逐渐减小；在蜗壳第三断面处，沿径向取3个压力脉动监测点，发现随着直径的增大，压力脉动幅度逐渐减弱，同时隔舌位置的压力脉动远大于蜗壳其他位置。

Study on Internal Vorticity Dynamics of Centrifugal Pump Volute Based on DDES

In order to study the vortex structure and the process of vortex evolution in the volute of centrifugal pump, the unsteady numerical simulation of vortex motion of centrifugal pump under multiple working conditions was carried outbased on the DDES turbulence model and the vorticity of vortex dynamics.Compared with the numerical simulation and experimental data of the characteristic, the difference between the two values was in the allowable range.This means the Delay Detached Eddy Simulation is reliable. Compared with the vorticity cloud images, DDES turbulence model obtains more clearly image to see the small vortex formed by the collapse of the large vortex and simulate the fine flow field structure better than RNG k-ε epsilon turbulence model. The vortex in the volute was mainly concentrated in the vicinity of the inlet and the tongue. The vortex flowed with the fluid, the large vortex was broke down into many small vortices, and the vorticity decreased gradually. As the flow rate increased, the vortex distribution in the flow path and the vorticitydecreased gradually. In the third section of the volute, three pressure fluctuation monitoring points were taken along the radial direction, and the pressure fluctuation decreased gradually with the of diameter increasing, and the pressure fluctuation of the tongue was much larger than that of the other parts of the volute.