| The bilge water transfer system for ships is an important system to ensure zero pollution and safety of ships.Rotary pump is the main power source of the transfer system,which has the characteristics of frequent starting and long working time.The research on vibration characteristics and vibration isolation base performance of rotor pump is of great significance to improve the acoustic concealment and comfort of ship equipment.In this paper,rotor pump and vibration isolation base are taken as the research object.The vibration characteristics of rotor pump in10Hz～10k Hz frequency domain are analyzed by theoretical analysis,numerical calculation and vibration test methods.The influencing factors of vibration isolation effect of vibration isolation base are analyzed and the optimal model is obtained.Specific research contents and results are as follows :1)Based on the rotor profile equation,the three-dimensional model of rotor and pump shell is established,and the transient numerical analysis of rotor pump fluid domain is carried out by dynamic mesh technology.The model of rotor clearance t = 0.4 mm,0.5 mm and 0.6 mm was established,and the variation laws of average flow Qavg,volumetric efficiency η and flow pulsation coefficient ξ with different rotor clearances were compared and analyzed.It is found that with the increase of the rotor clearance,the average flow,volumetric efficiency and flow pulsation coefficient gradually decrease.When the clearance t = 0.4 mm,the efficiency reaches the maximum of 70.5%.When the clearance t = 0.6 mm,the overall downward trend of the three flow performance indexes is more obvious.2)The statistical method is used to calculate the fluid excitation force of the pump shell,and the Fourier transform method is used to solve the power spectral density in the frequency domain,and the main frequency of the fluid excitation force in the three directions is analyzed.It is found that the excitation force pulsation law in the X and Y directions of the rotor pump shell is similar to the instantaneous flow pulsation law,and there are two high density humps;while the excitation force in the Z direction is chaotic and irregular.3)Based on the transient dynamics method of modal superposition method,the acceleration response value in the time domain of the pump shell base is solved,and the vibration acceleration level is calculated by using the 1/3 octave algorithm.The vibration acceleration level of rotor pump shell base with rotor clearance t = 0.4mm and 0.6mm is analyzed.The average vibration acceleration level of pump shell base increases in turn in three frequency bands,and the vibration acceleration level reaches the maximum at 2000 Hz,and the total vibration level of pump shell base is about 102 d B.4)The design concept of vibration isolation base is analyzed,and the vibration acceleration level of the height of the shape characteristic parameters and the thickness of the web are compared and the vibration isolation effect is evaluated.The research shows that the isolation base with the height of 180 mm and the thickness of 10 mm is the best.5)The L-shaped structure was used to optimize the vibration isolation base,and it was found that the vibration isolation performance of the L-shaped structure exceeded that of the traditional web-shaped vibration isolation base in the low and medium frequency bands.Especially in the low frequency band,the average vibration acceleration level decreased by nearly 40% compared with that of the pump shell base without vibration isolation base,and the vibration isolation effect increased by 28%.The mean decline rate of acceleration level in the middle frequency band also reached 22%,and the vibration isolation effect increased by 23%.It fully reflects the advantages of L-type vibration isolation base in low and medium frequency bands.6)Combined with vibration test measurement,it is found that the total vibration level index has the largest error proportion in all statistical indexes of vibration characteristics,and the error rate is 6%.However,from the whole frequency domain vibration acceleration level change trend,vibration isolation effect and total vibration level parameters,it is highly consistent with the transient dynamic numerical analysis. |
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