Experimental investigation of influence of strake wings on self-induced roll motion at high angles of attack

The modern high performance air vehicles are required to have extreme maneuverability,which includes the ability of controlled maneuvers at high angle of attack. However, the nonlinear and unsteady aerodynamic phenomena, such as flow separation, vortices interaction, and vortices breaking down, will occur during the flight at high angle of attack, which could induce the uncommanded motions for the air vehicles. For the high maneuverable and agile air missile, the nonlinear roll motions would occur at the high angle of attack. The present work is focused on the selfinduced nonlinear roll motion for a missile configuration and discusses the influence of the strake wings on the roll motion according to the results from free-to-roll test and PIV measurement using the models assembled with different strake wings at a = 60°. The free-to-roll results show that the model with whole strake wings(baseline), the model assembled with three strake wings(Case A)and the model assembled with two opposite strake wings(Case C) experience the spinning, while the model assembled with two adjacent strake wings(Case B), the model assembled with one strake wing(Case D) and the model with no strake wing(Case E) trim or slightly vibrate at a certain "×"rolling angle, which mean that the rolling stability can be improved by dismantling certain strake wings. The flow field results from PIV measurement show that the leeward asymmetric vortices are induced by the windward strake wings. The vortices would interact the strake wings and induce crossflow on the downstream fins to degrade the rolling stability of the model. This could be the main reason for the self-induced roll motion of the model at a = 60°.     

平面形状对MAV气动特性的影响

通过风洞测力实验研究了平面形状(后掠角)对展长/根弦长之比为1.0的机翼的气动特性的影响,实验结果表明,模型后掠角在很大程度上影响小展弦比机翼的气动特性,当模型后掠角Λ≤35°时,能增大模型的最大升力系数和失速迎角,推迟失速;当模型后掠角Λ=56°~64°时,能得到较好的升力曲线,改善机翼的失速特性。此外,实验结果表明模型前缘背风面倒角与迎风面倒角相比,有效地提高了模型的最大升阻比和失速后的升力系数。     

防空导弹翼面弹性支承边界参数识别

利用系统可测自由度上获得的不完全模态来识别尾翼的边界支承参数。直接由特征方程出发求解边界的未知位移和内力，借此计算边界动刚度，同时对带有一定误差的已知试验模态进行叠代修正，然后通过最小二乘法求解边界的支承刚度和附加质量。本文方法简捷。精度和效率都较高。在防空导弹及其他相关领域都有一定的应用价值。     

基于随机测量点的机翼精加工位姿计算方法

在机翼精加工过程中,需要对机翼的位姿进行计算,以指导其调整。通过对翼面水平测量原理的分析,提出一种基于随机测量点的机翼精加工位姿计算方法。首先,以翼面水平测量数据为基础,采用以最小二乘法为目标函数的迭代最近点算法,求解出测量点在翼面设计模型上的匹配点,形成位姿计算所需的2个点集。然后,运用Levenberg-Marquardt算法计算出这2个点集间的变换关系,实现位姿参数的求解。最后,为减少测量点误差对位姿计算的影响,给出了测量点精度补偿方法。仿真算例表明,该方法具有较高的计算精度,能够满足实际工程需求。     

X-47B飞翼气动布局设计分析

对X-47B双后掠飞翼布局的气动布局设计进行了研究,分析了前缘后掠角、外翼弦长等平面形状参数对单后掠、双后掠飞翼布局的气动及隐身特性的影响,讨论了内外翼采用不同前缘剖面形状的原因,总结了X-47B无人作战飞机布局的发展历程及详细设计阶段翼尖修形的效果,为飞翼布局飞机的气动隐身设计提供设计参考。     

大展弦比飞机模型边界层转捩模拟技术

针对大展弦比飞机模型高速风洞试验需求,进行了边界层转捩模拟技术研究.研究表明:与传统的金刚砂粗糙带相比,柱状转捩带具有粘贴牢靠、可操作性强等优势,已经推广应用于大展弦比飞机模型高速风洞试验;边界层转捩对大展弦比飞机模型气动特性有重要影响,不仅影响阻力,而且对升力与俯仰力矩均有明显影响;在目前国内低雷诺数风洞条件下建议在边界层固定转捩条件下进行风洞试验,以提高风洞试验精度.     

Shock/shock interactions between bodies and wings

This paper examines the Shock/Shock Interactions (SSI) between the body and wing of aircraft in supersonic flows. The body is simplified to a flat wedge and the wing is assumed to be a sharp wing. The theoretical spatial dimension reduction method, which transforms the 3D problem into a 2D one, is used to analyze the SSI between the body and wing. The temperature and pressure behind the Mach stem induced by the wing and body are obtained, and the wave configurations in the corner are determined. Numerical validations are conducted by solving the inviscid Euler equations in 3D with a Non-oscillatory and Non-free-parameters Dissipative (NND) finite difference scheme. Good agreements between the theoretical and numerical results are obtained. Additionally, the effects of the wedge angle and sweep angle on wave configurations and flow field are considered numerically and theoretically. The influences of wedge angle are significant, whereas the effects of sweep angle on wave configurations are negligible. This paper provides useful information for the design and thermal protection of aircraft in supersonic and hypersonic flows.     

某型飞机机翼液压管路优化设计与分析

针对某支线飞机试飞过程中机翼液压管路的故障问题展开分析研究,给出了排除故障的办法,对这部分管路进行了优化设计,并对相似机型的管路设计进行了对比分析,提出了机翼后缘导管设计的注意事项.     

考虑复合材料蒙皮稳定性的飞机翼面结构布局优化设计

 复合材料蒙皮稳定性是飞机翼面结构设计需要考虑的重要方面。由于翼面结构稳定性理论分析的复杂性,工程中,通常采用与理论分析相比拟的简化方法、使用简便可靠的经验公式在设计过程中进行稳定性校核。多墙式结构是当前翼面结构中普遍采用的结构形式,墙的布局和蒙皮的厚度对复合材料蒙皮的临界屈曲载荷有着重要影响。因此,针对多墙式翼面结构,以工程经验公式为基础,以蒙皮单位长度上的的重量为优化目标,以墙的布局参数和蒙皮厚度为设计变量,以临界失稳载荷为约束,建立了一种考虑复合材料蒙皮稳定性的翼面结构布局优化问题的数学模型,导出了目标函数敏度计算的解析式,并提出了优化问题的求解方法。以翼盒结构为例,验证了该方法的有效性。     

飞机机翼表面霜冰的三维数值模拟

基于欧拉两相流理论对三维情况下飞机机翼表面的霜冰进行了数值模拟.根据水滴拟流体模型建立三维水滴控制方程;提出一套水滴控制方程的数值求解方法;由三维水滴流场的求解结果计算机翼表面的水滴收集特性,提出一种三维积冰外形的生成方法,完成了对飞机机翼表面霜冰的三维数值模拟.对ONERA M6机翼在不同迎角下霜冰的积冰情况进行了数值预测,并分析了结冰条件对积冰的影响.