Noise And Vibration Reduction Analysis Of Large Launch Vehicle Fairing

Acoustic optimization of the launch vehicle is an important study of themodern space technology，The most significant in the whole process is to reduce thesound pressure level within the launch vehicle fairing,to protect the satellite andother precision instruments are not subject to noise damage. In recent years,Countries are increasing the intensity of the vibration and noise reduction studywithin fairing, There are a lot of new research methods and results.This paper first introduces the research status of the noise sources in flight ofthe rocket, Noise sources include the pulsating pressure of the atmosphere and thejet engine noise, simultaneously, it introduces the research status of the vibrationand noise reduction about launch vehicle fairing.Secondly, This paper describes the basic theory of the porous sound-absorbingmaterial in the noise reduction, After we build the rocket fairing model by statisticalenergy analysis and verify the reasonableness of model from two angles, two anglesis the actual connection form and the modal density, Analysising the change of theSound and vibration environment, the change arise from the absorption coefficientand different loss factor, studying the Sound and vibration environment of fairingSimilar structure.Then, we paste the full porous sound-absorbing materials for noise reductionin the fairing inner wall, and compare and Analysis the noise reduction effect offive different foam and five different fiber materials, Choosing two of the bestmaterials, For these two materials, we have two other different paste noisereduction method. One way is to paste the noise reduction materials by according tocoverage, another method is to paste a multi-layer sound-absorbing material in thefairing inner wall,we studied the paste sequence and the thickness of each layermaterial, They bring some effect of noise reduction results.Last, we analyzed a number of factors, these factors affect the noiseperformance of the material, and these factors have the performance parameters ofthe porous sound-absorbing material, including density, flow resistance, porosityand tortuosity factor. Simultaneously, factors include the external conditions of thematerial, Such as the air space, air humidity and temperature.