大迎角下翼型振动的气动性能研究

众所周知,风洞试验中的飞机模型,尤其是带有大展弦比机翼的模型有时会出现翼梢振动现象,振动模式主要表现为翼梢沉浮和俯仰形式,以致影响实验结果的精度和可靠性。选取相对厚度较小的NACA0008翼型,在求解非定常Navier-Stokes方程的基础上,采用改进的无限插值理论和绕翼型的C型网格,模拟风洞实验中模型振动条件下的流场,研究振动模式及其不同耦合对流场、尤其是大迎角流场的影响,并考虑了模型弹性轴不同位置对结果的影响。研究结果表明：在临近传统定常失速迎角的大迎角条件下,翼型的振动可以引起翼型大尺度的分离,导致翼型失速的提前发生;振动在不同的相位滞后条件下,对翼型流场的分离程度不尽相同。

Investigation of vibration on an airfoil aerodynamics at larger incidence

It is well known that the model wing may appear obvious vibration in wind tunnel experiments sometimes at high incidence especially in large aspect ratio aircraft models.The vibration modes mainly come in plunging and pitching which seriously affect the precision and reliability of wind tunnel experiments results.In this paper,the investigation of NACA0008 airfoil is carried out.Based on the unsteady Reynolds-Averaged Navier-Stokes equations,applying the modified infinite interpolation approach and the C type grid,the flow field and aerodynamic characteristics of the airfoil at high incidence are studied for simulating vibrations of wind-tunnel models,especially for the wind-tunnel airplane with high aspect ratio wing.Two vibration models and the phase delay between the different vibrations are also studied.It is shown that the vibrations of the airfoil can cause large scale unsteady separate vortex shedding before the stall incidence,and lead to the stall appearing at some lower incidence than the steady meaning stall incidence.The different phase delay has different effect on the flow-field.