Effect of the volute tongue cut on pressure pulsations of a low specific speed centrifugal pump
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Available online at https://link.springer.com/journal/42241 http://www.jhydrodynamics.com Journal of Hydrodynamics, 2020, 32(4): 758-770 https://doi.org/10.1007/s42241-020-0053-x
Effect of the volute tongue cut on pressure pulsations of a low specific speed centrifugal pump * Ning Zhang1, Bo Gao1, Bin Xia2, Qi-feng Jiang3 1. School of Energy and Power Engineering, Jiangsu University, Zhenjiang 212013, China 2. School of Mechanical Technology, Wuxi Institute of Technology, Wuxi 214121, China 3. Key Laboratory of Fluid and Power Machinery, Ministry of Education, Xihua University, Chengdu 610039, China (Received June 27, 2019, Revised July 26, 2019, Accepted August 5, 2019, Published online August 26, 2020) ©China Ship Scientific Research Center 2020 Abstract: 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. Key words: Centrifugal pump, volute tongue cut, pressure pulsation, spectrum analysis
Introduction Pressure pulsation in the centrifugal pump, mainly resulted from the intense rotor-stator interaction between the impeller and volute, is vital to the stable operation, noise and vibration of the pump[1]. When the impeller periodically sweeps the volute tongue, the non-uniform fluid discharged from the impeller will interact with the volute tongue. Thus, high pressure pulsations are induced[2]. So the shape and location of the volute tongue have a significant influence on pressure pulsations. For the low pressure pulsation design target, the distance between the impeller and volute tongue is usually selected much larger than the conventional recommended value[3]. It is proved that for centrifugal pumps, when the * Project supported by the National Natural Science Foundation of China (Grant Nos. 51706
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