民用飞机起落架气动噪声数值仿真

Aerodynamic Noise Simulation of Commercial Aircraft Landing Gear

对某型民用飞机前起落架进行气动噪声进行数值仿真分析。采用分离涡模拟方法,计算起落架周围非定常湍流流场,提取声源信息,利用FW-H方程积分外推法求解模型辐射的声场,获得噪声的频谱特性及远场指向特性曲线。通过频谱对比,研究粗网格和细网格对仿真精度的影响以及不同积分面对噪声预测结果的影响。结果表明,分离涡模拟方法能够较好地模拟流场中存在的大量复杂的涡结构;当选取模型固体表面为积分面时,基于粗网格比基于细网格计算的声压级低约1dB;基于细网格定义空间可穿透面为积分面比定义模型固体表面为积分面计算的声压级高约5～7dB;起落架气动噪声源与其后部有规律的涡脱落相关,并且噪声辐射具有明显的指向特性。

Aerodynamic noise of a commercial aircraft landing gear component is explored. The flow field around the landing gear is produced using detached eddy simulation （DES）. The source information is obtained. The acoustic field radiated from the model is calculated via FW-H equation. The influences of course/fine grid on simulation precision and porous/solid integration surface on noise prediction are eval- uated by spectra comparison. Frequency spectra and directivity characteristics are investigated. The re- sults show that DES displays the capability to resolve fine-grained turbulence and exhibits the complex vertical structures. The sound pressure level calculated based on the coarse grid is about 1 dB less than that calculated based on the fine grid when using the solid integration surface. The sound pressure level calculated from the porous surface is 5--7 dB greater than that calculated from the solid surface because of the quadrupole sources in the wake. The noise source is relevant to the vortex shedding behind the model. Noise radiation has obvious directivities.