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771.
Pressure distribution is important information for engineers during an aerodynamic design process. Pressure Distribution Oriented (PDO) optimization design has been proposed to introduce pressure distribution manipulation into traditional performance dominated optimization. In previous PDO approaches, constraints or manual manipulation have been used to obtain a desirable pressure distribution. In the present paper, a new Pressure Distribution Guided (PDG) method is developed to enable better pressure distribution manipulation while maintaining optimization efficiency. Based on the RBF-Assisted Differential Evolution (RADE) algorithm, a surrogate model is built for target pressure distribution features. By introducing individuals suggested by sub-optimization on the surrogate model into the population, the direction of optimal searching can be guided. Pressure distribution expectation and aerodynamic performance improvement can be achieved at the same time. The improvements of the PDG method are illustrated by comparing its design results and efficiency on airfoil optimization test cases with those obtained using other methods. Then the PDG method is applied on a dual-aisle airplane’s inner-board wing design. A total drag reduction of 8 drag counts is achieved. 相似文献
772.
A series of wind tunnel tests was conducted to examine how an end plate affects the pressure distributions of two wings with leading edge(LE) sweep angles of 23° and 40°. All the experiments were carried out at a midchord Reynolds number of 8×10~5, covering an angle of attack(AOA) range from -2° to 14°. Static pressure distribution measurements were acquired over the upper surfaces of the wings along three chordwise rows and one spanwise direction at the wing quarter-chord line. The results of the tests confirm that at a particular AOA, increasing the sweep angle causes a noticeable decrease in the upper-surface suction pressure. Furthermore, as the sweep angle increases, the development of a laminar separation bubble near the LEs of the wings takes place at higher AOAs. On the other hand, spanwise pressure measurements show that increasing the wing sweep angle results in forming a stronger vortex on the quarter-chord line which has lower sensitivity to AOA variation and remains substantially attached to the wing surface for higher AOAs than that can be achieved in the case of a lower sweep angle. In addition, data obtained indicate that installing an end plate further reinforces the spanwise flow over the wing surface, thus affecting the pressure distribution. 相似文献
773.
774.
空客A320系列飞机的襟/缝翼控制计算机对翼尖刹车线圈提供了相应的监控功能(包括开路和短路)。但是,不完善的监控逻辑可能导致一些奇怪的故障现象,影响维护人员对故障的判断,本文对其监控内涵进行深入分析。 相似文献
775.
776.
《中国航空学报》2020,33(7):1850-1866
Variable-camber technology is considered an effective way to adaptively improve the aerodynamic performance of aircraft under various flight conditions. This paper studies the aerodynamic characteristics of the trailing-edge variable-camber technology by means of Computational Fluid Dynamics (CFD) and a drag decomposition method. Trailing-edge variable-camber technology can be simply realized by the continuous deflection of the flaps and ailerons of a wing. A supercritical airfoil is used to study the two-dimensional effect of variable-camber technology, and a wide-body airplane model is used to validate the three-dimensional improvement in the wing's airfoil made by variable-camber technology. An optimization strategy for airfoil that incorporates variable-camber technology is proposed. The optimization results demonstrate that the proposed method can obtain better results than the traditional segregated shape optimization. 相似文献
777.
A closed-loop control allocation method is proposed for a class of aircraft with multiple actuators. Nonlinear dynamic inversion is used to design the baseline attitude controller and derive the desired moment increment. And a feedback loop for the moment increment produced by the deflections of actuators is added to the angular rate loop, then the error between the desired and actual moment increment is the input of the dynamic control allocation. Subsequently, the stability of the closed-loop dynamic control allocation system is analyzed in detail. Especially, the closedloop system stability is also analyzed in the presence of two types of actuator failures: loss of effectiveness and lock-in-place actuator failures, where a fault detection subsystem to identify the actuator failures is absent. Finally, the proposed method is applied to a canard rotor/wing (CRW) aircraft model in fixed-wing mode, which has multiple actuators for flight control. The nonlinear simulation demonstrates that this method can guarantee the stability and tracking performance whether the actuators are healthy or fail. 相似文献
778.
小展弦比飞翼标模尾部畸变影响试验研究 总被引:1,自引:0,他引:1
在飞翼布局模型风洞试验中,为实现尾部支撑需对模型进行尾部修形。为摸清飞翼布局模型局部外形畸变的影响规律,本文在 FL-14风洞对某小展弦比飞翼布局原始模型和尾部外形畸变模型进行了试验研究,采用增量法获得了尾部外形畸变的影响规律,并与国内三座低速风洞的三种支撑装置的近/远场支架干扰进行了对比分析。研究结果表明:小侧滑角时,在小迎角范围内尾部畸变影响量显著大于支架干扰量,在中大迎角范围则与支架干扰量级相当;畸变横向影响量较大,且随侧滑角增大而增大。所以应对全机的试验结果进行正确的“畸变”修正,或对尾部畸变外形进行优化,以减小畸变的影响。 相似文献
779.
基于雷诺平均Navier-Stokes(RANS)方程和结构网格技术,采用亚跨超声速平台(TRIP3.0),数值模拟了美国国家航空航天局(NASA)梯形翼构型。研究了控制方程、网格密度、流动转捩和初始条件等不同影响因素对气动特性的影响。风洞试验是2002年在NASA Langley 14ft×22ft亚声速风洞中完成的,试验结果包括了基本气动力和力矩、表面压力系数和边界层速度型分布。计算结果与试验数据的比较表明:求解完全的RANS方程,提高了翼梢涡的模拟精度;网格密度主要影响翼梢涡的强度;转捩模型提高了边界层的模拟精度,进而提高了升力系数、俯仰力矩系数的模拟精度;最大升力系数及失速迎角对初始条件具有依赖性。 相似文献
780.