The knowledge of wing orientation and deformation during flapping flight is necessary for a complete aerodynamic analysis, but to date those kinematic features have not been simultaneously quantified for free-flying i...The knowledge of wing orientation and deformation during flapping flight is necessary for a complete aerodynamic analysis, but to date those kinematic features have not been simultaneously quantified for free-flying insects. A projected comb-fringe (PCF) method has been developed for measuring spanwise camber changes on free-flying dragonflies and on beating-flying dragonflies through the course of a wingbeat, which bases on projecting a fringe pattern over the whole measurement area and then measuring the wing deformation from the distorted fringe pattern. Experimental results demonstrate substantial camber changes both along the wingspan and through the course of a wingbeat. The ratio of camber deformation to chord length for hind wing is up to 0.11 at 75% spanwise with a flapping angle of -0.66 degree for a free-flying dragonfly.展开更多
Using the method of elasticity, an analytical approach is developed to analyze the shear stress in a honeycomb wing structure with a large aspect ratio under the condition of free torsion. The formulas of shear stress...Using the method of elasticity, an analytical approach is developed to analyze the shear stress in a honeycomb wing structure with a large aspect ratio under the condition of free torsion. The formulas of shear stress, warping and angle of twist are derived. These formulas are both useful and convenient from the point of view in the structure design.展开更多
飞翼布局因其独特的翼身融合的气动外形,大大提高了飞行器的有效升力面积,外形优化问题和布局优化对于此类构型气动性能的提升同样重要。本文为解决飞翼布局无人机气动外形优化问题,建立了高效的参数化建模方法,实现了适应复杂外形的几...飞翼布局因其独特的翼身融合的气动外形,大大提高了飞行器的有效升力面积,外形优化问题和布局优化对于此类构型气动性能的提升同样重要。本文为解决飞翼布局无人机气动外形优化问题,建立了高效的参数化建模方法,实现了适应复杂外形的几何参数化变形控制,将基于梯度的优化算法、离散伴随方法与基于RANS(Reynolds average Navier-Stokes)方程的计算流体力学(Computational fluid dynamics,CFD)方法相结合,对飞翼布局无人机完成了气动外形的优化减阻设计,升阻比提升了7.17%。优化结果表明,在满足约束要求的前提下,基于上述技术的气动优化设计方法对翼身融合类构型具有良好的适应性,能有效改善无人机的气动性能。展开更多
将连续伴随方程法与自由变形技术(Free Form Deform-FFD)相结合开展了跨声速机翼气动外形优化设计方法研究。采用Bernstein基函数建立了空间FFD参数化方法,并应用基于控制理论的连续伴随方程方法建立了目标函数对于待优化几何外形的梯...将连续伴随方程法与自由变形技术(Free Form Deform-FFD)相结合开展了跨声速机翼气动外形优化设计方法研究。采用Bernstein基函数建立了空间FFD参数化方法,并应用基于控制理论的连续伴随方程方法建立了目标函数对于待优化几何外形的梯度求解模式,将几何外形参数化方法、连续伴随方法以及CFD数值模拟技术相结合,研究、构建了适合跨声速机翼的气动外形优化设计系统。利用该系统对ONERA M6机翼及某型民用客机机翼进行了气动减阻设计,算例验证表明该方法应用于跨声速机翼气动减阻设计效果明显,并且能较好的保持几何表面连续性和光滑性。展开更多
通过在三角翼上游加入干扰圆柱的风洞实验方法，研究了来流干扰对微小型飞行器MAV（Micro Air Vehicle）气动特性的影响．结果表明，在刚性和弹性三角翼顶点上游加入圆柱干扰时，两者均出现缓失速，刚性翼产生缓失速与干扰圆柱尾流关系...通过在三角翼上游加入干扰圆柱的风洞实验方法，研究了来流干扰对微小型飞行器MAV（Micro Air Vehicle）气动特性的影响．结果表明，在刚性和弹性三角翼顶点上游加入圆柱干扰时，两者均出现缓失速，刚性翼产生缓失速与干扰圆柱尾流关系密切，弹性翼的缓失速不仅与此有关，还与弹性翼的振动有关．无干扰或在机翼顶点加入干扰时，在攻角为4^o～18^o内弹性翼的升力系数比刚性翼的要大，但升阻比相对要小．由于弹性翼的振动与机翼绕流结构、气动力之间的耦合，弹性翼顶点与翼尖振动的主频随着攻角增大呈规律性的变化，失速攻角附近翼尖的振动主频是其涡脱落频率．展开更多
文摘The knowledge of wing orientation and deformation during flapping flight is necessary for a complete aerodynamic analysis, but to date those kinematic features have not been simultaneously quantified for free-flying insects. A projected comb-fringe (PCF) method has been developed for measuring spanwise camber changes on free-flying dragonflies and on beating-flying dragonflies through the course of a wingbeat, which bases on projecting a fringe pattern over the whole measurement area and then measuring the wing deformation from the distorted fringe pattern. Experimental results demonstrate substantial camber changes both along the wingspan and through the course of a wingbeat. The ratio of camber deformation to chord length for hind wing is up to 0.11 at 75% spanwise with a flapping angle of -0.66 degree for a free-flying dragonfly.
文摘Using the method of elasticity, an analytical approach is developed to analyze the shear stress in a honeycomb wing structure with a large aspect ratio under the condition of free torsion. The formulas of shear stress, warping and angle of twist are derived. These formulas are both useful and convenient from the point of view in the structure design.
基金supported by the Key Laboratory of Icing and Anti/De-icing of China Aerodynamics Research and Development Center (CARDC) (No. IADL20210203)the Natural Science Foundation of Sichuan, China (No.2023NSFSC1393)+1 种基金the Scientific Research Starting Project of Southwest Petroleum University (SWPU) (No.2021QHZ001)the National Natural Science Foundation of China (No.52006235)。
基金supported in part by the National Natural Science Foundation of China(No.11972180)。
文摘飞翼布局因其独特的翼身融合的气动外形,大大提高了飞行器的有效升力面积,外形优化问题和布局优化对于此类构型气动性能的提升同样重要。本文为解决飞翼布局无人机气动外形优化问题,建立了高效的参数化建模方法,实现了适应复杂外形的几何参数化变形控制,将基于梯度的优化算法、离散伴随方法与基于RANS(Reynolds average Navier-Stokes)方程的计算流体力学(Computational fluid dynamics,CFD)方法相结合,对飞翼布局无人机完成了气动外形的优化减阻设计,升阻比提升了7.17%。优化结果表明,在满足约束要求的前提下,基于上述技术的气动优化设计方法对翼身融合类构型具有良好的适应性,能有效改善无人机的气动性能。
文摘将连续伴随方程法与自由变形技术(Free Form Deform-FFD)相结合开展了跨声速机翼气动外形优化设计方法研究。采用Bernstein基函数建立了空间FFD参数化方法,并应用基于控制理论的连续伴随方程方法建立了目标函数对于待优化几何外形的梯度求解模式,将几何外形参数化方法、连续伴随方法以及CFD数值模拟技术相结合,研究、构建了适合跨声速机翼的气动外形优化设计系统。利用该系统对ONERA M6机翼及某型民用客机机翼进行了气动减阻设计,算例验证表明该方法应用于跨声速机翼气动减阻设计效果明显,并且能较好的保持几何表面连续性和光滑性。
文摘通过在三角翼上游加入干扰圆柱的风洞实验方法，研究了来流干扰对微小型飞行器MAV（Micro Air Vehicle）气动特性的影响．结果表明，在刚性和弹性三角翼顶点上游加入圆柱干扰时，两者均出现缓失速，刚性翼产生缓失速与干扰圆柱尾流关系密切，弹性翼的缓失速不仅与此有关，还与弹性翼的振动有关．无干扰或在机翼顶点加入干扰时，在攻角为4^o～18^o内弹性翼的升力系数比刚性翼的要大，但升阻比相对要小．由于弹性翼的振动与机翼绕流结构、气动力之间的耦合，弹性翼顶点与翼尖振动的主频随着攻角增大呈规律性的变化，失速攻角附近翼尖的振动主频是其涡脱落频率．
