余热排出泵内部压力脉动特性分析

为了研究余热排出泵内部压力脉动特性,基于ANSYS CFX软件,采用SST湍流模型,对模型泵进行三维非定常数值模拟,得到了余热排出泵的水力性能,并与试验结果进行对比,计算了泵内不同位置的压力脉动情况,对计算结果进行了时域和频域分析.研究结果表明:叶轮与导叶内的压力脉动均呈现周期性变化,叶轮内周期为7,压力脉动与导叶叶片数密切相关,导叶内周期为5,压力脉动与叶轮叶片数密切相关;叶轮进口、中间流道、叶轮出口的压力脉动系数幅值分别为0.018 23,0.106 76,0.177 51,压力脉动信号逐渐增强,导叶进口、中间流道、导叶出口的压力脉动系数幅值分别为0.095 56,0.076 02,0.012 44,压力脉动信号逐渐减弱;叶轮内监测点的主频均为7f_p,压力脉动主要由转频决定,从叶轮进口至出口导叶的影响程度逐渐增强,导叶进口主频为15f_p,中间流道和出口主频为5f_p,导叶内压力脉动主要由叶频决定,沿流道至出口叶轮的影响逐渐削弱;蜗壳监测点主频为35f_p,压力脉动主要由叶频决定,且与导叶叶片数相关.

Pressure fluctuation in residual heat removal pumps

In order to investigate the characteristics of pressure fluctuation in residual heat removal pumps, three-dimensional unsteady numerical simulations were conducted by the SST turbulence model in ANSYS CFX. The performance of the residual heat removal pump was obtained and compared with the experimental results. The pressure fluctuations at various monitoring points were measured and analyzed in time and frequency domains. The results indicate that the pressure fluctuations in impeller and diffuser change periodically. The period of the pressure fluctuation within impeller is 7. The pressure fluctuation is closely related with the blade number in diffuser, while the period within diffuser is 5 and the fluctuation is strongly linked with the blade number in impeller. The amplitudes of pressure fluctuation at inlet, middle area and outlet of the impeller are 0.018 23, 0.106 76, 0.177 51, respectively. The amplitudes at inlet, middle area and outlet of the diffuser are 0.095 56,0.076 02,0.012 44,respectively. The amplitudes within impeller increase gradually from the inlet to outlet but the transformation law within the diffuser is opposite. The main frequency of pressure fluctuation within impeller which is dominated by the rotation speed is 7f_p. The fluctuation is increasingly affected by the diffuser from the inlet to outlet. The main frequency at the inlet of diffuser is 15f_p, while the others are 5f_p. The fluctuation frequency within the diffuser is determined by the blade passing frequency. The fluctuation is decreasingly affected by the impeller from the inlet to outlet of the diffuser. The main frequency within volute is 35f_p, which means that the fluctuation within volute is determined by the blade passing frequency and related with the blade number of diffuser.