论文部分内容阅读
依据翼型理论分别提取四种鸟类翅膀沿展向40%截面处的翼型,采用大涡模拟结合声类比的FW-H方程的方法对不同仿生翼型进行流场及声场的模拟。非定常流场的计算结果表明,在逆压梯度作用下,气流在叶片吸力面前缘开始分离;在叶片下游处产生了明显的涡结构,脱离叶片尾缘后涡结构发生破碎。在四种仿生翼型中,海鸥翼型的升阻比最大,鹗翼的升阻比最小,但鹗翼具有优良的降噪特性。声压级的方向性分布揭示了仿生翼型声源具有偶极子声源特性。
According to the airfoil theory, the airfoils at four percent cross sections of wings of four birds were extracted respectively. The large-eddy simulation and the FW-H equation of acoustic analogies were used to simulate the flow field and the sound field of different bionic airfoils. The results of unsteady flow field show that the airflow begins to separate at the suction edge of the blade under the action of the reverse pressure gradient, and vortex structure is formed at the downstream of the blade. The vortex structure is broken after it leaves the trailing edge of the blade. Among the four kinds of bionic airfoils, the gull-wing has the highest lift-drag ratio and the smallest drag-drag ratio, but the gull wing has excellent noise reduction characteristics. The directional distribution of sound pressure level reveals the dipole sound source characteristics of the bionic airfoil.