The volute tongue, as the crucial component inducing rotor-stator interaction, is detrimental to unsteady pressure pulsations of centrifugal pumps. In the present paper, to investigate the effect of the volute tongue cut on pressure pulsations of a low specific speed centrifugal pump, three volute tongues are obtained through twice cuts, named cases 1, 2, 3. Twenty measuring points are evenly mounted on periphery of the volute casing to obtain unsteady pressure signals using high response transducers. Pressure amplitudes at the blade passing frequency f_BPF and root mean square (rms) values in 0 Hz-500 Hz frequency band are applied to evaluate the cutting effect. Results show that pressure spectrum is significantly affected by the volute tongue cut, especially for the component at f_BPF. For different measuring points, influences of the volute tongue cut on three cases are not identical. From rms values, it is evident that cutting the volute tongue will lead to pressure energy increasing for most of the concerned measuring points, especially for the points at the far away region from the volute tongue. Finally, from comparison with the original shape case 1, the averaged increment of the twenty points is more than 20%. So it is concluded that for this type centrifugal pump, cutting the volute tongue is not reasonable considering low pressure pulsation requirement.

中文翻译：

---

蜗壳切舌对低比转速离心泵压力脉动的影响

蜗壳榫舌是引起转子与定子相互作用的关键部件，对离心泵的不稳定压力脉动有害。在本文中，为了研究蜗壳切舌对低比转速离心泵压力脉动的影响，通过两次切割获得了三个蜗壳切舌，分别称为案例1、2、3。在圆周上均匀地安装了二十个测量点使用高响应换能器对蜗壳进行旋转以获得不稳定的压力信号。刀片通过频率f _BPF处的压力幅度和0 Hz-500 Hz频带中的均方根（rms）值可用于评估切割效果。结果表明，蜗壳切舌对压力谱有显着影响，特别是对于f处的分量_BPF。对于不同的测量点，蜗壳切舌对三种情况的影响并不相同。从均方根值可以看出，切割蜗壳榫舌会导致大多数相关测量点的压力能量增加，尤其是远离蜗壳榫舌的区域的点。最后，通过与原始形状案例1进行比较，二十个点的平均增量超过20％。因此可以得出结论，对于这种类型的离心泵，考虑到低压脉动的要求，切开蜗壳舌是不合理的。