مدل سازی محاسباتی و تایید تجربی از رفتار ارتعاشی آکوستیک بخش های بدنه هواپیما
|کد مقاله||سال انتشار||تعداد صفحات مقاله انگلیسی||ترجمه فارسی|
|153289||2018||11 صفحه PDF||سفارش دهید|
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Publisher : Elsevier - Science Direct (الزویر - ساینس دایرکت)
Journal : Applied Acoustics, Volume 132, March 2018, Pages 8-18
The aerodynamics of an aircraft impose significant stresses upon its structure. The turbulent boundary layer (TBL) is a highly turbulent layer that forms along the fuselage skin inducing localized pressure fluctuations resulting its vibration, and in turn, the generation of noise inside the passenger cabin. During flight, the noise generated by the TBL dominates the sound field between 100â¯Hz and 5â¯kHz, to be regarded as the frequency range of interest. While the audible range is between 20â¯Hz and 20â¯kHz, human hearing and speech intelligibility is most sensitive between 250â¯Hz and 2â¯kHz. This investigation considers a BEM-FEM-BEM modelling technique to predict the vibro-acoustic response of the fuselage and an experimental methodology to verify the results (following ASTM and ANSI testing standards) by imitating the frequency profile of the TBL using an acoustic source. The research incited construction of an atypical acoustic testing facility, the development of DAQ software and post-processing techniques of test data. The principal quantity of interest is transmission loss. Four panels (0.04â¯in., 0.063â¯in. (milled pockets to 0.043â¯in.), 0.063â¯in., and 0.09â¯in. in thickness) were simulated and tested between 20â¯Hz and 20â¯kHz. Analysis of the results sought to determine the limitations of the computational methodology by observing divergence of the predictions from the results. Divergence was defined as a difference exceeding 10% (approximately 4â¯dB), which was observed beyond 8â¯kHz. The comparisons show the frequency-averaged errors between the proposed methodologies to be within 5â¯dB between 20â¯Hz and 20â¯kHz, and 3â¯dB between 100â¯Hz and 5â¯kHz. Variability in reproducibility of experimental results (same test specimen and between test specimens) is a significant challenge when determining transmission loss values. The experimental methodology proved successful in differentiating between the panels with confidence using at least six tests over a period of three years. The computational methodology was accurate in estimating the transmission loss and the general (frequency-dependent) response.