Research Article Experimental Study of Pressure Pulsation in a Mixed-Flow Pump with Different Tip Clearances Based on Wavelet Analysis Leilei Ji, 1 WeiLi , 1,2 Weidong Shi , 3 Ling Zhou, 1 and Ramesh Agarwal 4 1 Research Center of Fluid Machinery Engineering and Technology, Jiangsu University, Zhenjiang 212013, China 2 Institute of Fluid Engineering Equipment Technology, Jiangsu University, Zhenjiang 212009, China 3 College of Mechanical Engineering, Nantong University, Nantong 226019, China 4 Department of Mechanical Engineering & Materials Science, Washington University in St. Louis, St. Louis, MO 63130, USA Correspondence should be addressed to Wei Li; lwjiangda@ujs.edu.cn and Weidong Shi; wdshi@ujs.edu.cn Received 23 January 2020; Revised 28 April 2020; Accepted 1 July 2020; Published 25 July 2020 Academic Editor: Shuaishuai Sun Copyright © 2020 Leilei Ji et al. is is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. In order to investigate the eﬀect of various impeller tip clearances on the pressure pulsation in a mixed-ﬂow pump, the energy performance test and pressure pulsation experiment of a mixed-ﬂow pump with diﬀerent tip clearances are studied simulta- neously. e pressure pulsation signals at impeller inlet, middle, and oulet are processed and analyzed by the wavelet transform. e results show that the change of tip clearance can aﬀect the head and eﬃciency of mixed-ﬂow pump. Under designed ﬂow rate, when the tip clearance increases from 0.2mm to 1.1 mm, the head and eﬃciency decrease by 18.1% and 11.6%, respectively. Due to the strong inﬂuence of blade passing frequency (BPF) at impeller middle, the period of pressure pulsation curve is about 1/4 of impeller rotation period. At impeller inlet, the low-frequency pulsation with energy concentration is the main disturbance frequency, and, with the increase of tip clearance, not only does the high-value region of wavelet spectrum expand to low- frequency direction but also it is easy to form second-order peaks in the time-averaged wavelet curve. At impeller outlet, aﬀected by BPF and rotor-stator interaction (RSI), the high-frequency disturbance in RSI area decreases ﬁrst and then increases. e wavelet coherence demonstrates the stable low-frequency disturbances in comparison to others and it will aﬀect the ﬂow ﬁeld at impeller middle. 1.Introduction e mixed-ﬂow pump is a common hydrodynamic ro- tating mechanical device widely used in engineering [1–5] due to its moderate head and the capacity of transporting a largerﬂowrate.Asthesemiopenimpellerisusuallyusedin the mixed-ﬂow pump, the internal ﬂow ﬁelds of a mixed- ﬂow pump are extremely complex and totally turbulent, including tip leakage ﬂow (TLF) [6, 7], back ﬂow [8], and vortex shedding from the blade tip region [9], as well as the RSI between the impeller and guide vane [10]. Among the all complex ﬂows, the TLF, driven by the high-pressure gradient between the blade pressure surface and suction surface, will aﬀect most of the ﬂow ﬁelds of impeller ﬂow channels and make the pump eﬃciency drop a lot [11]. e TLF will entrain with mainstream in impeller channel and form three types of vortexes: tip leakage vortex, tip sep- aration vortex, and the induced vortex. Among the three types, the TLV occupies the dominant position. ere is a sharp drop of pressure in the formation region of the TLV, which may lead to serious pressure pulsation and threaten the operation safety. Furthermore, the pressure pulsation in the mixed-ﬂow pump is relatively strong enough to induce vibration of pump system and extra hydraulic forces together with some high-frequency noise [12, 13]. In fact, in the hydraulic design of mixed-ﬂow pump [14], there is no relevant theory to support the design of tip clearance sizes, but the tip clearance size has a strong business with the strength of TLF. erefore, it is necessary to do some researches of pressure pulsation of mixed-ﬂow pump with diﬀerent tip clearances to reveal the mecha- nism of TLF. Hindawi Shock and Vibration Volume 2020, Article ID 9041686, 15 pages https://doi.org/10.1155/2020/9041686