基于吹吸气控制的飞行器大攻角气动性能提升方法研究
STUDY OF IMPROVING METHOD OF AERODYNAMIC PERFORMANCE FOR AN AIRCRAFT AT HIGH ANGLES OF ATTACK BASED ON BLOWING AND SUCTION CONTROL
-
摘要: 流动控制是改善飞行器气动性能、拓展飞行包线的重要途径. 以往流动控制设计较少考虑实际流动情况, 导致控制方法和参数设计存在难实现等问题. 本文提出了通过吹吸气调控前缘涡进而改善大攻角气动性能的涡扰动控制原理, 以一个飞翼布局飞机为例, 阐述了如何依据未控制工况的翼面流动压力信息设计控制参数, 并且验证了控制效果和可操作性. 首先, 研究了一个后掠角为65°的小展弦比飞翼标模的纵向气动特性, 发现该飞翼标模会在38°攻角下发生升力失速和力矩失速. 其次, 在涡扰动控制原理的指导下, 设计了沿飞行器前缘分布的4个吹吸气狭缝, 研究了在机翼不同位置分别施加吹气、吸气时的控制效果. 进一步, 设计了前段狭缝吹气与后段狭缝吸气联合控制方法, 翼面压强分布和控制参数设计表明, 该方法可将吸气口吸入的气体经由吹气口吹出, 从而可在不依赖外部气源供气的情况下实现控制. 控制效果分析表明, 吹吸气联合控制能够增强前缘涡强度和负压、延缓前缘涡破裂, 进而显著提高后失速阶段的升力系数, 延缓失速后升力系数和俯仰力矩系数的掉落, 拓展飞行包线. 综上, 本文提出的控制原理和方法基于飞行器翼面实际流动情况设计, 方法有效、可操作性强, 具有重要价值.Abstract: Flow control is an important approach to improve the aerodynamic performance of aircraft and expand flight envelope. Previous flow control designs rarely considered actual flow conditions, leading to problems such as difficulty in implementing control methods and parameter designs. This paper proposes a control principle based on vortex disturbance that improves aerodynamic performance by regulating leading-edge vortex through blowing and suction at high angles of attack. Taking a flying-wing configuration aircraft as an example, it elaborates on how to design control parameters based on the pressure information of the flow over an uncontrolled aircraft, and further verifies the control effect and operability. First, the longitudinal aerodynamic characteristics of a low-aspect-ratio flying-wing aircraft with a sweep angle of 65° are studied, and it was found that the aircraft would experience lift stall and moment stall at an angle of attack of 38°. Second, under the guidance of the control principle based on vortex disturbance, four blowing and suction slots distributed along the leading edge of the aircraft are designed, and the control effect of applying blowing and suction at different positions of the wing is studied. Furthermore, a combined control method of blowing from the front slots and suction from the rear slots is proposed. The pressure distribution on the wing surface and the design of control parameters show that this method can blow out the gas sucked in by the suction ports through the blowing ports, thus realizing control without relying on external air source. Analysis of the control effect shows that the combined blowing and suction control can enhance the intensity and negative pressure of the leading-edge vortex while delaying vortex breakdown, thereby significantly increasing the lift coefficient in the post-stall phase, delaying the drop of the lift coefficient and pitching moment coefficient after stall, and expanding the flight envelope. In summary, the control principle and method proposed in this study are designed based on the actual flow conditions on the aircraft wing surface, which are effective, highly operable, and of great value.
下载: