Analysis Of Vibration And Acoustic Radiation Characteristics Of Twin-screw Pumps

Actually the physical reasons of vibration and noise are the same but phenomena are different,the vibration and noise levels play an important role in evaluation of the machinery in modern industry.The vibration and acoustic radiation behavior of the whole double-screw pump is to great extent determined by the dynamic properties and the hydraulic pressure inside.The double-screw pump is one kind of high-speed rotating machines,the inside liquid runs along the screw axis in the meshing space between the two screws.During the procedure,the liquid is kept being pressurized and reaches the maximum value at the outlet of the pump.Because of the impact of changing pressure,the pump parts begin to cause annoying vibration.And the cyclical behavior of pump liquor flow also leads to the phenomenon of cavitation and back flow which cause vibration intensified at the same time.The noise caused by hydraulic vibrations and mechanical vibrations occurs with increasing pressure.Due to the complex work condition in the twin-screw pump,the mechanical noise is produced by the interaction among inside parts,it is too difficult to establish a mathematical model to calculate the pump vibration and noise.In a real-world environment,a major reason for this is the difficult to accurately measure the vibration and noise level,and the test will cost a lot.Thus,taking the finite element method into consideration at the conception stage,and the results are verified by experiment.This paper comprehensively analyses the designed double-screw pump's vibration and acoustic characteristics from theory,parameter calculation,modeling,fluid analysis,acoustic-structural analysis and vibration test.1.As a core element in the double-screw pump,the type of screw rotor line will directly affect various pumping performance.This article has presented a new series of rotor line consists of cycloid,long amplitude and arcs.The cycloid has several advantages,for instance,high contact ratio factor,good sealing performance driving stable and etc,which makes it can satisfy low level in vibration and noise of pump.2.According to the project's research objective and required parameters,this article describes the design process of the key components,establishes a virtual model of double-screw pump via 3D modeling software UG and SolidWorks.Assembling simulation and interference analysis are done,which shows that the results of early design is reasonable.3.Based on the fluid mechanics theory,CFD simulation was made of the inner flow field ofthe twin-screw pump by GAMBIT and FLUENT.After study the pressure nephogram and velocity vector of the pump model,the dynamic characteristics of inner flow space can be investigated more exactly.4.This paper puts forward the acoustic-vibration coupling method used in mechanical transmission system of the designed double-screw pump.And the numerical analysis of sound radiation is processed by software ANSYS Workbench,on the basis of that,this paper obtains the vibration and radiated noise characteristics of mechanical drive unit to provide some references for the coming assessments of vibration and noise level and pump structure optimum design and improvement5.The double-screw pump prototype has been made and it's vibration characteristics are tested.All the acceleration data is collected and studied with the data signal acquisition and data analysis software to get the vibration intensity of observation posts,and then,the working condition level of double-screw pump can be evaluated at the same time.