翼型加速飞行过程中气动力特性研究

Aerodynamic characteristics of an airfoil during acceleration

在飞行器起飞或者发射过程中,飞行器速度是变化的,因此气动力特性是非定常的。通过NACA4412翼型以固定加速度加速飞行过程来研究飞行器气动力与加速度的关系及攻角变化对这种关系的影响。计算结果显示,同样速度下,升力系数随加速度增大而减小,阻力系数随加速度增大而增大,速度越大,受加速度的影响越小;加速度一定时,随着速度增加,升力系数增加,阻力系数减小;阻力中的附加惯性力影响突出,升力则相反,历史效应均随时间流逝而减少;攻角变化时,升阻力特性变化趋势与无攻角时一致;加速飞行有效改善了失速特性。

During aircraft＇ s take-off and launch,their aerodynamic characteristics are unsteady for a changing speed. This paper investigated relationship between aircraft aerodynamics and its acceleration,and effects of varied attack angles on the relationship by Computational Fluid Dynamics（ CFD） to observe flight of NACA4412 airfoil with a fixed acceleration. The results showthat lift coefficient decreases while drag coefficient increases with increasing acceleration under the same speed. The higher the speed,the less the effect of the speed on drag coefficient. However,the lift coefficient increases while drag coefficient decreases with increasing speed under a constant acceleration. The additional inertial force for drag coefficient is remarkably affected,but the lift coefficient has an opposite trend. History effects for the lift coefficient reduced with time. Furthermore,the lift and drag characteristics are consistent with the changes of attack angle. The accelerated flight effectively improves stall characteristics.