中文摘要：

为了研究低比转速离心泵内由叶轮/蜗壳相互作用所引起的非定常流动特性,基于滑移网格和RNGk-ε湍流模型计算了具有4长8短复合叶轮离心泵内部的非定常流动。计算结果显示,离心泵内部速度和压力在空间上呈现高度非对称性,在时间上呈现高度非定常性。蜗壳第Ⅳ断面和第Ⅷ断面速度变化规律基本一致,周向速度沿蜗壳径向减小,第Ⅷ断面出现负的径向速度,流动最为复杂。叶轮和蜗壳的动静耦合是产生压力脉动的主要原因,压力脉动的频率受叶轮转频控制,主频为叶片通过频率。蜗壳周向的脉动压力幅值呈现上下波动,但从第Ⅰ断面到第Ⅷ断面其幅值整体上在逐渐衰退,直到蜗壳第Ⅷ断面达到最小。与定常计算相比,在设计点下非定常计算所得的有效扬程更接近实验值,说明非定常计算可以比较准确地预测泵的扬程。

英文摘要：

To investigate the unsteady flow characteristics caused by interaction between the impeller and volute in the low-specific-speed centrifugal pump, the unsteady flow field of a centrifugal pump with four- long and eight-short blades was simulated based on sliding mesh and RNG κ-ε turbulence model. The simulation results of velocity and static pressure show highly asymmetric in space as well as highly unsteady in time. The velocities on sections IV and Ⅷ of volute have the same trend, and the circumferential velocity decreases along the radial direction of volute. The change of radial velocity magnitude on section Ⅳis less than that on section Ⅷ because section Ⅳ is away from the tongue and is less influenced. The flow near the volute is the most complex and the radial negative velocity appears on section Ⅷ. The rotor-stator coupling is the main reason for pressure fluctuation, whose frequency is dominated by impeller rotating frequency, and the dominant frequency is blade passing frequency. The amplitude of fluctuation pressure along the volute fluctuates from section Ⅰ to section Ⅷ, and its average value declines gradually until section Ⅷ reaches a minimumvalue. Compared with the steady calculation, the effective head calculated by unsteady calculation is closer to experimental value at design point, indicating that the unsteady calculations can predict the pump head accurately.