蜻蜓滑翔时三维串列柔性双翼气动效能分析

为进一步揭示蜻蜓翼在被动的柔性变形和串列双翼柔性干涉作用下对气流的影响机制，本文基于STAR-CCM+软件，采用流固耦合方法对Navier-Stokes方程进行数值求解。研究了杨氏模量为3 800 MPa、泊松比为0.25时，蜻蜓柔性复翼的变形及其气动特性响应规律。研究表明：蜻蜓翼保持正向高置差气动布局均会带来相似且有益的影响。迎角5°时，1.2 mm的高置布局相比低置气动布局的升力系数提升了5.2%，当迎角增大到25°时，差值达到19%。双翼干涉效应下，前翼的气动特性会得到明显的提升，后翼虽会损失一定的气动力，但总体而言，动态干涉是有益的。从双翼气流分离下诱导的后缘涡强度来看，后翼的涡要明显强于前翼。9 m/s以后，蜻蜓滑翔时由前翼承担主要载荷的方式缓慢过渡到后翼，而且后翼翼梢处受载较明显，其最大变形达到16 mm；扭转变形方面：速度一定时，随着滑翔时失速迎角增大，后翼的动态弯扭变形明显强于前翼，验证了蜻蜓翼大迎角下利用后翼机动滑翔的观点。

Aerodynamic efficiency analysis of 3D tandem flexible wings in dragonfly gliding

In order to further reveal the influence mechanism on the airflow under the passive flexible deformation and interference of the flexible tandem wings, based on STAR-CCM+ software, this paper solves the Navier-Stokes equations using the fluid-solid coupling method numerically. When Young''s modulus is 3 800 MPa, and the Poisson''s ratio is 0.25, the deformation and aerodynamic response of the dragonfly flexible tandem wings are studied. Studies have shown that maintaining a favorable high-displacement aerodynamic layout of dragonfly wings will bring similar and beneficial effects. When the angle of attack is 5°, the lift coefficient of the 1.2 mm high-position layout increases by 5.2% compared with the low-position aerodynamic layout. When the angle of attack increases to 25°, the difference reaches 19%. Under the tandem wing interference effect, the aerodynamic characteristics of the front wing will be significantly improved. Although the rear wing will lose a certain amount of aerodynamic force, in general, dynamic interference is beneficial. Judging from the strength of the trailing edge vortex induced by the separation of the airflow between tandem wings, the vortex of the rear wing is significantly more potent than that of the front wing. After 9 m/s, when the dragonfly glides, the main load is slowly transitioned from the front wing to the rear wing, the tip of the rear wing is significantly loaded, and its maximum deformation reaches 16 mm; in terms of torsional deformation: when the speed is constant, with the stall angle of attack increases during gliding, the dynamic bending and torsional deformation of the rear wing is significantly more potent than that of the front wing, which verifies the view that the rear wing usually used for maneuvering gliding under the large angle of attack of the dragonfly wing.