Optimization of aerodynamic efficiency for twist morphing MAV wing

Twist morphing(TM) is a practical control technique in micro air vehicle(MAV) flight.However, TM wing has a lower aerodynamic efficiency(CL/CD) compared to membrane and rigid wing. This is due to massive drag penalty created on TM wing, which had overwhelmed the successive increase in its lift generation. Therefore, further CL/CDmaxoptimization on TM wing is needed to obtain the optimal condition for the morphing wing configuration. In this paper, two-way fluid–structure interaction(FSI) simulation and wind tunnel testing method are used to solve and study the basic wing aerodynamic performance over(non-optimal) TM, membrane and rigid wings. Then,a multifidelity data metamodel based design optimization(MBDO) process is adopted based on the Ansys-DesignXplorer frameworks. In the adaptive MBDO process, Kriging metamodel is used to construct the final multifidelity CL/CDresponses by utilizing 23 multi-fidelity sample points from the FSI simulation and experimental data. The optimization results show that the optimal TM wing configuration is able to produce better CL/CDmaxmagnitude by at least 2% than the non-optimal TM wings. The flow structure formation reveals that low TV strength on the optimal TM wing induces low CDgeneration which in turn improves its overall CL/CDmaxperformance.     

助推滑翔变体飞行器弹道方案多目标近似优化

针对助推滑翔变体飞行器弹道方案最优变形求解难、多设计指标相互矛盾等问题,开展助推滑翔变体飞行器弹道方案多目标设计优化研究。首先构建了助推滑翔变体飞行器全程弹道方案优化框架,通过内外层分别优化控制参数及弹道方案参数,并建立了以起飞质量最小、射程最大为优化目标的弹道方案多目标优化模型。在弹道建模中,基于牛顿迭代法建立助推段弹道模型,基于伪谱法建立最优变体再入滑翔段弹道模型。此外,提出了基于差分进化的多目标近似约束优化方法(MACO-DE),实现助推滑翔变体飞行器弹道方案优化。对比初始方案,在射程不变情况下,起飞质量至多降低3.81%,在起飞质量不变情况下,射程至多提升6.62%,从而验证了全程弹道模型的合理性与MACO-DE方法的有效性。     

变弯度后缘与常规舵面机翼的颤振主动抑制对比

后缘变弯度机翼的气动弹性建模与稳定性分析日益受到关注。为了探究变弯度后缘相比常规偏转舵面机翼颤振主动抑制的方法与特点，以一个小展弦比后缘变弯度机翼为对象，首先建立结构有限元模型，并引入变弯度后缘变形模态和常规舵面偏转模态，采用亚声速偶极子格网法计算非定常气动力；然后使用基于最小状态法的有理函数拟合进行频域到时域模型的转换，建立两种构型机翼的气动弹性模型，并在建模时考虑了变弯度后缘与常规舵面控制带宽的差异；最后利用线性高斯二次型方法设计控制律进行颤振主动抑制，分析对比两种控制方式的特性差异。结果表明：采用变弯度后缘的闭环系统能够将颤振临界速度提高22%，其提升效果优于常规舵面，所需舵面偏转峰值更小。