Subjects: Mechanics >> Applied Mechanics submitted time 2023-03-20 Cooperative journals: 《应用力学学报》
Abstract： In order to the study the characteristics of open-rotor noise in low speed , CFD ( computationalfluid dynamics)/CAA ( computing aerodynamic acoustics ) hybrid method of the open-rotor tone noise wasset up.N-S equation is expanded by NLH method in the frequency domain, and the unsteady componentsare obtained.'These unsteady components and steady load are used to construct Lighthill sound source.Fi-nally ,FW-H integration method is used to calculate far-field noise radiation. The noise experimental plat-form is built and test scheme is designed.The noise directivity in the range of 0� -90� is measured by usingthe far-field directivity array surround scale prototype. The characteristic of the noise of open-rotor is ana-lyzed by comparing the numerical simulation results and experimental results. The results show that inter-action noise is the major component of open-noise.'The simulation results are basically consistent with thedistribution trend of the experimental results at key frequency ,the error is within 3 dB.'The numerical sim-ulation method of aerodynamic noise based on nonlinear harmonic method is developed to solve unsteadydisturbance in frequency domain , which can provide some help for rapid and accurate prediction of open rotor noise.
Subjects: Mechanics >> Applied Mechanics submitted time 2023-03-20 Cooperative journals: 《应用力学学报》
Abstract： In onder to study the transmission loss of composite laminate under high frequency noise excita-tion , first , the laminate is equivalent to a single-layer anisotropic panel based on the general laminate theo-ry. Then, the transmission loss model of equivalent single-layer panel is established by SEA method , andmodal density , coupling loss factor , and other important input paramelers are calculated. Last , the trans-mission loss of laminate panel is obtained and compared with the experimental results. The results showthat the prediction results of transmission loss are basically consistent with the distribution trend of the ex-perimental values. However, due to the limitation of SEA method and the influence of stiffness equivalenton the inherent characteristics and radiation efficiency of laminate panel , the emor of low frequency band(200 H:-2 500 Hz) is above 3 dB. The high frequency band (2 500 Hz-10 000 Hz) prediction results a-gree well with the experimental values , and the error is within 3 dB. The two-dimensional equivalent SEAmodel of laminate panel can provide certain help for the rapid and accurate prediction of sound transmission characteristics of composite laminates under the excitation of high frequency noise in the process ofnoise reduction design and optimization.
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