核主泵内部流动干涉的瞬态效应研究

Transient Effects for Flow Interaction in the Flow Field of Nuclear Main Pump

为了揭示核主泵叶轮和导叶的流动干涉效应,采用相似换算法和多参数匹配法,基于RNG k-ε湍流模型与块结构化网格,对缩比系数为0.5的模型泵进行非定常数值模拟。结果表明:扬程脉动幅值与运行工况有关,额定工况时扬程脉动的幅值最小,偏离最优工况时,扬程脉动幅值逐渐增大。导叶内部流道产生不稳定的流量脉动效应,大于0.8Qd工况时,导叶内流量脉动瞬态效应不明显;小于0.8Qd工况时,导叶内流量脉动趋于不稳定。考虑到机组的水力稳定性,运行工况应大于0.8Qd。动静干涉使导叶内静压分布呈现周期性脉动,导叶压力面平均脉动幅值最大,吸力面平均脉动幅值最小,压力脉动的周期与叶轮叶片数有关;导叶内静压分布与叶轮尾缘和导叶前缘相对位置有关,叶轮尾缘对导叶入口流动的阻塞效应,是诱发导叶内静压脉动的主要原因。

In order to reveal flow interference effects of impeller and guide vane of a nuclear main pump, adopting similar conversion algorithm and multiple parameters matching method, based on RNG k-ε turbulence model and block structured grids, unsteady numerical simulation was carried on the model pump whose shrinkage coefficient is 0.5. The results show that the pulsation amplitude of the head is related to operating conditions, the minimal value is on the rated condition, and it will gradually increase when the working condition deviate from the optimal point. The unstable flow pulsation effect appears in the inner flow passage of the guide vane, the transient effect of the flow pulsation of the inside guide vane is not obvious when the working condition is above 0.8Qd,; the flow pulsation within the guide vane tends to be unstable when the working condition is under 0.8Qd,. Considering the hydraulic stability of the unit, working condition should be above 0.8 Qd. Rotor-stator interaction induces periodic pulsation of the guide vane static pressure distribution, the average pulsation amplitude on the pressure side is maximum,and the suction side is minimum. The pressure pulsation period is related to the impeller blade number. The guide vane static pressure distribution is related to the relative position of the impeller trailing edge and the guide vane leading edge; the impeller trailing edge caused the blockage effect on the guide vane inlet flow, and it＇s the main reason causes the guide vane static pressure pulsation.