摘要
The large-eddy simulation(LES)with the dynamic Smagorinsky model is used to predict the interior sound of an idealized vehicle cabin under the excitation of the wall pressures from turbulent channel flows.In comparison with direct numerical simulation(DNS),the LES results overpredict the sound pressure level(SPL)at low frequencies and underpredict the SPL at high frequencies.The incorrect predictions result from the incorrect prediction of LES on surface pressures,where the LES over-estimates the wavenumber and frequencies spectra of surface pressures at small wavenumbers and frequencies and under-estimates the spectra at large wavenumbers and frequencies.However,the LES results are close to the filtered-DNS results,implying that the unresolved scales are also important to surface pressures and interior sound.The Euler-Bernoulli beam under the excitation of exterior pressures,which serves as a simple model for aero-vibro-acoustics in the case of hydrodynamical fast,is used to explain the observed predictions and show that the Corcos model cannot represent the variation of turbulence pressure spectra at wavenumbers and frequencies.Therefore,the new requirement for the LES method,when applied to fluid-structural-acoustic interaction problems at high Reynolds numbers,is the correct prediction of wavenumber and frequency spectra of turbulence wall pressure.
高雷诺数流固声耦合的大涡模拟是湍流和计算流体力学的前沿领域.它可以用于飞机、潜艇和新能源汽车的舱内噪声预测.本文设计了槽道湍流激励下的平板-空腔系统作为典型案例,研究了大涡模拟方法用于高雷诺数流固声耦合系统的可能性.我们的数值结果表明,基于动态Smagorinsky模型的大涡模拟方法得到的振动声学响应与直接数值模拟接近,但是在高频部分低估了振动声学响应,并在低频部分高估响应.其主要原因在于大涡模拟未能准确预测壁面压力时空能谱,而时空能谱决定了流固声耦合系统的振动声学响应.通过Corcos模型激励的Euler-Bernoulli梁的理论分析,我们确认了不准确壁面压力时空能谱影响振动声学响应的机制.最后,本文工作表明了有必要通过发展新型的亚格子项模型,提升壁面压力时空能谱的预测精度,最终实现大涡模拟方法对高雷诺数流固声耦合系统的准确预测.
作者
Lixing Zhu
Ting Wu
Guowei He
朱力行;吴霆;何国威(The State Key Laboratory of Nonlinear Mechanics,Institute of Mechanics,Chinese Academy of Sciences,Beijing,100190,China;School of Engineering Science,University of Chinese Academy of Sciences,Beijing,100049,China)
基金
Basic Science Center Program of the National Natural Science Foundation of China for“Multi-scale Problems in Nonlinear Mechanics”(Grant No.11988102)
National Key Project(Grant No.GJXM92579).
