中文摘要：

为了揭示复杂泵体水力的不稳定性,以减压塔底泵为例,利用计算流体动力学（CFD）对泵内部非定常流场进行数值模拟计算.根据得到的蜗壳内压力脉动情况,对其时域和频域进行分析.结果表明：各工况下压力脉动频率均以叶片通过频率为主,且次级蜗壳内的压力脉动比首级要明显;蜗壳内压力脉动最大值出现在隔舌附近,且沿蜗壳流道螺旋线方向压力脉动幅值依次减小;设计工况下蜗壳内压力脉动强度小于非设计工况下的,次级蜗壳隔舌处小流量工况下压力脉动幅值约为设计流量时的2.63倍.

英文摘要：

Taken a decompression tower bottom pump as an example,the unsteady flow was simulated numerically by using CFD（computational fluid dynamics） to reveal the instability of hydraulic performance in complex pumps.According to the obtained pressure fluctuations inside the volute,time domain and frequency domain were analyzed.The results show that the blade passing frequency under different conditions dominates the pressure fluctuations and it become more obvious in the secondary volute.The pressure fluctuations decrease in the direction of volute,and the maximum occurs near the tongues.The pressure fluctuations in the volute are relatively low at the design flow rate condition.The amplitude of pressure fluctuations near the secondary volute under the low flow rate condition is 2.63 times larger than that of design condition.