边条翼布局双垂尾抖振实验与数值研究

【作者】 李劲杰；

【导师】 杨永年；

【作者基本信息】 西北工业大学 ， 流体力学， 2006， 硕士

【摘要】 本文对新一代战斗机广泛采用的气动布局形式——边条翼双垂尾布局的垂尾抖振特性进行了深入研究,包括风洞实验研究和数值模拟研究。 实验研究方面的内容和成果主要有四个方面: (1)边条翼布局飞机模型双垂尾抖振风洞实验研究。设计了双垂尾抖振响应测量的实验方案,并初步研究了某边条翼布局的飞机模型的双垂尾抖振响应特性。通过实验检验了实验方案的正确性、可行性,并通过垂尾的根部弯矩测量和翼尖加速度测量得到了双垂尾的抖振响应曲线和抖振起始迎角,掌握了边条翼布局的双垂尾抖振响应随迎角变化的规律,即在抖振起始迎角之前,双垂尾的抖振响应很小且基本不随迎角变化,当迎角超过抖振起始迎角时,抖振响应急剧增加并在某一迎角范围达到最大值,之后抖振响应逐渐降低。 (2)边条翼布局飞机模型双垂尾抖振发生机理风洞实验研究。通过激光片光源流场显示技术研究了边条涡随迎角的发展和破裂特性,以及垂尾附近的破裂涡流场。结合该模型的垂尾抖振实验表明,该边条翼布局模型的垂尾抖振响应随迎角的变化特性与边条涡流场随迎角的发展和破裂特性是一致的,从而验证了边条破裂涡是引起双垂尾抖振的主要原因。 (3)边条翼布局双垂尾抖振表面脉动压力的风洞实验研究。测量和研究了垂尾表面脉动压力随迎角的变化特性,并将垂尾表面脉动压力积分近似得到垂尾的根部弯矩响应。将压力积分所得的根部弯矩响应曲线与垂尾根部应变片所测得的根部弯矩响应曲线比较发现二者符合得很好,从而进一步验证了边条翼布局的双垂尾抖振是由边条涡破裂气流作用在垂尾表面上的脉动载荷引起的,并且这种振动属于强迫振动。 (4)边条翼布局各主要参数对其双垂尾抖振响应的影响研究。通过翼根弯距测量,翼尖加速度测量和表面脉动压力测量研究了边条后掠角,机翼后掠角,垂尾的展向、弦向位置等主要参数对双垂尾抖振响应的影响。为工程应用和型更多还原

【Abstract】 In this thesis, the twin-vertical-tails buffet of strake-wing layout which is the primary configuration of the new generation of fighter is investigated, by both wind tunnel experiments and numerical simulations.The wind tunnel experiments include four aspects:1) A wind tunnel investigation of twin-vertical-tails buffet of a strake-wing layout was conducted to study the test method of tail buffet. The test method include root bending moment measurement and tip acceleration measurement. The root-mean-square (RMS) values of root bending moment and tip acceleration were used to scale the buffet intensity. The characteristics of twin-vertical-tails buffet of the strake-wing layout was also studied in the test.2) A flow visualization experiment was conducted to study the vortex flow field of the strake-wing layout at high angles of attack, using a laser light sheet technique. Combining with the result of the vertical tail buffet characteristic obtained from the wind tunnel experiment, the visualization experiment came to the conclusion that: The bursting of the vortex shed from leading-edge-extension (LEX) is the primary contributor to the twin-vertical tail buffet.3) A wind tunnel investigation was conducted to study the unsteady pressures on the surface of the vertical tail in buffet. The unsteady pressures were integrated along the surface to yield the root bending moment of the vertical tail. The root bending moment computed from root bending strain was also discussed. Then the RMS bending moments measured by two different method were compared. Results show that they are consistent well with each other. So the unsteady load of vortex breakdown flow impinging on the vertical tail is the primary contributor of the vertical tail buffet.4) The last wind tunnel investigation was conducted to study the influence ofthe primary parameters of strake-wing layout on the twin-vertical-tails buffet, including the influences of sweep angle of LEX, sweep angle of wing, chord-wise and span-wise position of vertical tail on the buffet of vertical tail.The contents of numerical simulation of twin-vertical-tails buffet consists of three aspects:1) The LU-SGS implicit time-stepping scheme was used to solve 3-dimensional compressible Euler equations. Combining the grid reordering technology, a much higher efficient Euler equations solver for 3-D unstructured mesh was developed.2) The Roe scheme of flux difference splitting was used to discrete the spatial flux, this scheme could simulate the separated flow field at high incidence efficiently.3) The numerical simulation of the twin-vertical-tails buffet of several different strake-wing layout were conducted, using the time accurate unsteady Euler equations solver developed in the thesis. The development and breakdown of the LEX vortex was investigated, along with the unsteady pressures on both sides of the vertical tail. Then the unsteady pressures were integrated along the surface to yield the root bending moment of the vertical tail. The numerical simulation explained the mechanism and characteristics of twin-vertical-tails buffet of strake-wing layout in detail. And the results were consist well with experiments data, that proved the feasibility of Euler equations for simulating the vertex breakdown and the tail buffet caused by vertex breakdown or separated flow.更多还原