基于动态重叠网格的折叠翼展开过程非定常气动加热数值模拟

Unsteady aerodynamic thermal numerical simulation of folding wing deployment process based on dynamic overset grid

  • 摘要: 相比于传统高速飞行器,折叠翼飞行器除了面临常规固定翼的气动加热问题外,还面临翼展开过程中带来的局部热扰动问题,对防热设计提出严峻挑战。针对折叠翼飞行器动态展开过程中的气动热环境特性,建立了基于刚体运动理论和动态重叠网格方法的非定常数值模拟方法。通过构建折叠翼简化模型,系统分析了翼面展开过程中的非定常流场演化特征及其气动加热规律。研究结果表明:与准定常仿真计算结果相比,两种方法得到的热流分布总体上基本一致,但是在局部存在由非定常热效应产生的热流差异:随着折叠翼面展开,翼尖和翼中部处非定常热效应凸显,翼尖处热扰动与当地线速度较大有关,翼中部处热扰动与时变的波系干扰和热累积有关;飞行攻角对大折叠角度状态下翼前缘热流影响较为明显,攻角–10°与10°的热流在相同位置的差值可达2055 kW/m2;飞行马赫数减小,翼前缘受到的激波干扰强度减弱,翼前缘热流分布的起伏程度也相应减弱。本研究揭示了折叠翼动态展开过程中的关键热环境特征,为高速变体飞行器的防热设计提供了理论依据。

     

    Abstract: Folding wings are increasingly being adopted to expand aircraft flight envelopes due to their capability to increase the lift-drag ratio and payload capacity. However, compared with traditional fixed-wing aircraft, this configuration not only inherits the aerodynamic heating problems associated with fixed wings but also introduces extra localized thermal disturbance during the wing deployment, imposing a severe challenge to thermal protection design. In this paper, we propose a method for simulating the unsteady aerodynamic heating of a simplified folding-wing aircraft model during wing deployment using dynamic overset grids. The unsteady aerodynamic heating environment during the deployment of the folding wing is numerically investigated using the newly developed unsteady method and the conventional quasi-steady method, focusing on the unsteady flow fields around a rotating folding wing and the variation trend of the aerodynamic heating during the deployment process as well as the dependence on the freestream condition. The heat flux distributions obtained by the two methods are generally consistent, but local distributions in heat flux arise from unsteady thermal effects: pronounced unsteady thermal effects manifest at both the wingtip and mid-span regions during the folding process. The thermal disturbances at the wingtip are related to the strong local linear velocity, while that at the mid-span is associated with time-varying wave interference and heat accumulation. The flight angle of attack has a more pronounced effect on the heat flux at the wing leading edge under large folding angle configurations; the difference in heat flux between angle of attack of -10° and 10° at the same location can reach 2055kW/m2. As the flight Mach number decreases, the intensity of shock wave interference acting on the wing leading edge weakens, and the magnitude of fluctuations in the heat flux distribution at the wing leading edge correspondingly diminishes.

     

/

返回文章
返回