Research On Vibration Reduction Mechanism And Influencing Factors Of Thrust Bearing With Hydraulic Pulsation Attenuator

When the ship is moving,due to the non-uniform flow field in the stern,the propeller will produce low-frequency axial pulsation.The axial pulsating force excites the shafting to produce axial vibration,which is transmitted to the hull through the shafting,causing damage to the ship structure and a certain impact on the ship's comfort.Therefore,it is of great significance to reduce the axial vibration of ship shafting.Studies have shown that the installation of hydraulic vibration damping devices on ship thrust bearings can effectively reduce its axial vibration,it is necessary to study the vibration reduction mechanism and influencing factors of the hydraulic vibration reduction device.Firstly,the vibration damping mechanism of hydraulic pulsating attenuator is analyzed.Based on the four-terminal parameter method,it is simplified and a theoretical model is established to obtain its transfer matrix.Then the theoretical model of the thrust bearing with the device is established and the vibration level drop and insertion loss from the thrust shaft to the shell are derived.The research shows that the designed hydraulic pulsation attenuator has certain damping effect in the frequency range of 1-200 Hz.Secondly,the finite element method is used to simulate the three-dimensional model.Compare and analyze the obtained simulation results with theoretical results.The results show that the calculation results of the two in the 1-200 Hz frequency band are similar,and the correctness of each other is verified.The simulation analysis of the hydraulic pulsation attenuator and the two-stage series hydraulic pulsation attenuator of the double-cylinder common chamber show that the two variant structures can improve the axial vibration damping effect to a certain extent,but at the same time increase the peak value at the resonance frequency.Then,the influence of different types of hydraulic oil on the vibration damping performance of hydraulic pulsation attenuator was studied.Considering the actual environment of hydraulic oil work,68 # lubricating oil was selected as the working medium.The effects of changes in the main structural parameters of the tubing diameter,tubing length,fuel tank volume,and hydraulic cylinder diameter on the attenuation of axial vibration are also analyzed.Studies have shown that in the 1-200 Hz frequency band,the vibration level drop value increases slightly with the increase of the inner diameter of the tubing and the volume of the fuel tank,and decreases slightly with the increase of the length of the tubing and the hydraulic rigid diameter.Based on genetic algorithm,Matlab software is used to optimize the main structural parameters of the hydraulic pulsation attenuator,and a set of parameters with the best vibration reduction effect is obtained within the range allowed by the variables.Finally,in order to make the vibration reduction analysis of the thrust bearing with hydraulic pulsating attenuator more convenient,the interface of the whole theoretical model was written with the help of the GUI in Matlab software,and the components and operating steps of the interface of the software were introduced in detail.The calculation of the effect of the hydraulic pulsation attenuator on the axial vibration of the thrust bearing is achieved.Through the research in this paper,the influence of relevant parameters on the vibration damping performance of the hydraulic pulsation attenuator is obtained,which has certain reference value for the design of the hydraulic pulsation attenuator and the research of the axial vibration damping of the shafting.