Experimental study on unbalanced response characteristics of the impeller of mixed transport pump in deep-sea mining

Abstract

The mixed transport pump is the core equipment of hydraulic lifting deep-sea mining system. The conveying medium is a solid-liquid two-phase flow. The impeller is prone to mass eccentricity due to the wear of ore particles. Therefore, it is great significance to study the unbalanced response characteristics of the impeller of the mixed transport pump. The unbalanced test of the impeller of the pump was carried out in a closed-cycle test bench. The unbalanced response characteristics were proved by data analysis method. The results indicated the hydraulic performance of the pump with the rotor system balance quality grade in G2.5 (scheme 2) was better than that of the balance quality grade in G6.3 (scheme 1). The pump efficiency was increased by 3.12%. When the medium was a solid-liquid two-phase flow, the amplitude of the vibration acceleration level (L_a) of the pump outlet flange in scheme 2 was generally lower in the low frequency range than that in scheme 1. The periodic variation law of the pump outlet pressure coefficient (C_p) was obvious. With the increase in the volume fraction of ore particle, the amplitude of the main frequency of the L_a in scheme 1 gradually was increased, which were 91.16, 97.11, and 102.57 dB, respectively. The main frequency amplitude of scheme 2 was basically unchanged. The main frequency amplitude change rates of the two schemes were −1.72%, −7.58%, and −12.78%, respectively. With the increase in the running time, the periodic change trend of the time-domain signal of the pump outlet flange vibration acceleration in scheme 1 was more obvious than that in scheme 2. The axial passing frequency amplitude was gradually increased. The pump efficiency was gradually decreased. Finally, the sliding bearing B₂ was severely worn and the service life was greatly reduced.