Vibration Transfer Analysis of Unbalance-Rubbing-Bearing Fault of Centrifugal Pump Considering Measuring Point of Machine Foot

Marine centrifugal pump is usually installed vertically in order to save equipment space. The sensor which can obtain the vibration status of centrifugal pump in real time can't be installed directly in the pump body, but can only be installed in the foot of the machine, resulting in the real-time status monitoring and fault diagnosis of centrifugal pump difficult to carry out. In order to solve this problem, the vibration transmission of the rotor system of centrifugal pump was analyzed, and the response law of vibration signals of the foot of centrifugal pump to different faults was proposed in this paper. According to the internal structural constraints of the centrifugal pump, a dynamic model containing rotor unbalance-rubbing-bearing fault was established, which took into account the unbalance fault, rotor-static rubbing fault, clearance of rolling bearings, nonlinear Hertzian contact between ball and raceway, the VC vibration caused by the change of rolling bearing support stiffness force and the damage dynamic model of the rolling bearing outer ring. At the same time, the transfer path of pump body and foot is introduced. The numerical integration method is used to carry out dynamic simulation analysis, and the results show that the dynamic model of centrifugal pump unbalance-rubbing-bearing fault proposed in this paper is correct and effective. The vibration response of measuring points of pump body and feet to different faults is analyzed by simulation data, and verified by experimental data. The analysis results show that the unbalance fault will lead to the increase of the power frequency amplitude of the vibration response of the pump body and the machine foot of the centrifugal pump. The rubbing fault will cause the 2nd, 4th, and 6th frequency amplitudes of the power frequency to be prominent in the vibration response spectrum of the pump body and the machine foot. When there is a bearing fault, the signals of the centrifugal pump foot and the pump body can be enveloped demodulated to extract the characteristic frequency of the bearing fault.