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High-efficiency prediction method for helicopter global/ground noise based on near-field acoustic holography

Chinese Journal of Aeronautics 2024年第7期37卷 271-284页

作者： Mengxue SHAO Yang LU Xice XU Jiaxin LU National Key Laboratory of Helicopter Aeromechanics Nanjing University of Aeronautics and AstronauticsNanjing 210016China

Noise reduction program design is an effective approach that relies on efficient noise prediction for reducing ground noise during *** existing noise prediction methods have the limitations of being computationally expensive or only applicable to *** this paper,a High-Efficiency Prediction Method(HEPM)for helicopter global/ground noise based on near-field acoustic holography is *** HEPM can predict the global noise based on acoustic modal analysis and has the advantages of high prediction accuracy and low time *** process is given as follows:firstly,the rotor noise on the holographic surface in the specified flight is obtained by simulations or ***,the global noise model,which maps time-domain noise to acoustic modes,is established based on near-field acoustic holography and Fourier acoustic analysis ***,combined with acoustic modal amplitude,the model established enables efficiently predicting the global/ground noise in the corresponding flight *** verify the accuracy of the prediction method,a simulation study is conducted in hovering and forward flight states using a model helicopter with a 2-meter rotor and Rotor Body Interaction(ROBIN)*** comparison of HEPM with numerical results shows that the average prediction errors of the global and ground noise are less than 0.3 dB and 0.2 dB,*** a region containing 100000 observers,the computation time of the HEPM is only one-fifth of that of the acoustic hemisphere method,demonstrating the rapidity of the proposed method.

关键词： Helicopter Rotor noise prediction Noise abatement procedure design acoustic modal analysis near-field acoustic holography

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Plant disease analysis and research based on the cylinder near-field acoustic holography

Plant disease analysis and research based on the cylinder ne...

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2011年全国压电和声波理论及器件应用研讨会

作者： Xiu-qing WANG Yin-chao WANG Jing-ya ZHANG~* College of Electronic Information and Automation,Tianjin University of Science and Technology,Tianjin 300222

＜正＞The plants suffer from the disease stress can produce the acoustic Emission *** order to understand the acoustic emission signal distribution regularities,seeking for the relationship between the degree of plant disease and acoustic emission *** paper used the near-field acoustic holography,built reconstructed model of cylinder near-field acoustic holography based on Spatial Transformation of Sound fields, gave out the reconstruction algorithm of sound field information,and then used the MATLAB software *** constantly adjusted the parameters such as the holographic face size,the spacing of measurement points,the holographic radius,the reconstruction radius and so on,obtained the optimal parameters which can identity the sound soure collectly,so as to direct the detection and location of actual holographic. Through added the filtering window function to the wave number domain,improved the frequency identification range and *** simulation results showed that use of cylinder near-field acoustic holography based on Spatial Transformation of Sound fields can be applied to recognition and positioning plant disease stress acoustic Emission signal accurately,to achieve the purpose of the early detection of plant disease,provided a new mathod and pathway for plants disease prevention and control method.

关键词： near-field acoustic holography the plants stress acoustic Emission signal

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AN APPLICATION OF THE NEURAL NETWORK IN THE near-field acoustic holography

AN APPLICATION OF THE NEURAL NETWORK IN THE NEAR-FIELD ACOUS...

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2006年中国机械工程学会年会暨中国工程院机械与运载工程学部首届年会

作者： GAO Yinhan, SONG Dan, LIANG Jie, ZHOU Xiaohua Center of Test Science of Jilin University, Jilin University Changchun 130022 China

The near-field acoustic holography (NAH) is an effective and useful noise measurement method. There are many methods for reconstruction of the sound source, but the measurement circumstance is limited

关键词： Neural network near-field acoustic holography noise source random noise.

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