【作者】 王林；

【导师】 刘冰；

【作者基本信息】 国防科学技术大学 ， 航空宇航科学与技术， 2009， 硕士

【摘要】 作为一种新兴的主动流动控制技术,合成射流正日益受到广大科技工作者的关注。合成射流激励器是合成射流技术发展的核心,其设计水平和工作性能决定了合成射流技术的应用方向和应用效果。合成双射流激励器作为合成射流技术的最新发展成果,不仅具有普通单腔体激励器的工作特点,还具有能量利用率高,结构紧凑、易于小型化,环境适应能力强等优点。本文采用理论分析与数值模拟相结合的方式,研究了不同激励器结构构型下的合成双射流流场,及合成双射流在机翼分离流动控制方面的应用。本文的研究内容和结论主要体现在以下四个方面:(1)数值模拟结果表明合成双射流是由两股相位差为180°的射流融合而成,在整个周期内合成双射流流场中始终存在一对较强的旋涡控制着下游流动。相对于单腔体合成射流,合成双射流一个周期内具有两个速度峰值,在靠近激励器出口处合成双射流具有更强的射流“穿透力”,在远离出口的下游,合成双射流具有更稳定的流动特征和更高的流动速度。(2)通过改变合成双射流激励器左右腔体设计可以实现射流的矢量性偏转,并且偏转效果随激励器结构参数和驱动参数不同而变化;通过改变两出口间距离的大小,可以控制两股射流间的融合效果,改变下游流场分布;斜出口合成双射流可以在近壁面形成一股附壁流,以实现对周围流体有方向性的动量和能量传递。(3)合成双射流对平板流动具有两种不同的影响效果:当射流垂直进入外部主流时,对主流起到“阻拦”作用,会在激励器出口产生“虚拟气动外形”效应,并使下游边界层变厚;当合成双射流以一定夹角进入外流时,可以实现对边界层的动量注入效应,使边界层厚度变薄,速度型更“饱满”。(4)合成射流和合成双射流均可以改善失速状态下的机翼气动特性,合成双射流具有更好的控制效果和控制能力,对最大升力和失速攻角的增加量都可达到单腔体合成射流的2倍。以外部主流流动特征频率倍频和较大动量系数工作的合成双射流激励器具有更好的改善机翼气动特性的能力。更多还原

【Abstract】 As a novel method of active flow control technology, synthetic jet is attractingmore researchers’attention. The application of synthetic jet technology to flow controlsystem is based on the synthetic jet actuator’s design level and work performance. As anup-to-the-minute result of the synthetic jet technology, dual synthetic jets actuator notonly has the property of the existing synthetic jet actuator, but also has the superiority ofhigh energy efficiency, compact structure, easy miniaturization and strongenvironmental adaptation.In this paper, the flow field of different actuator structure and the application inseparate flow control of an airfoil are studied in theory and numerical, the main workincludes four parts as follows:(1) The dual synthetic jets are merged by two jets with phase difference of 180degree, on the whole actuator cycle the downstream of the dual synthetic jets flow-fieldis controlled all along by a pair of strong vortexes. Compared with synthetic jet, dualsynthetic jets have two velocity peaks within one actuator cycle, in the near fielddownstream, the dual synthetic jets have stronger jet penetration and in the far fielddownstream, the merged jet is more stable and has higher velocity.(2) By changing the left and right cavity could vector the direction of the mergedjet, and the deflection is varied with different structural parameters and drivenparameters; by changing the distance between the exits could control the merge of theadjacent jet, and then influence the far flow-field; an increase in the exit angle couldlead to a wall-flow near the wall, it means that the energy and mass flux of fluid nearthe exit could be transmitted horizontally.(3) Dual synthetic jets have two different influence to the flat plate boundary layer:if the jets are injected perpendicular to the cross-flow, they will play a blocking role tothe mainstream and alter the effective shape of the body through“virtual aeroshaping”effect, then increase the thickness of the boundary layer; if the jets are injectedobliquitous, they will have the effective of increase the momentum of the boundarylayer, thin the boundary layer down and make the speed-type fuller.(4) Both of synthetic jet and dual synthetic jets could control flow separation of anairfoil, but dual synthetic jets have better performance and stronger capability, theincrement of the maximum lift and stall angle of attack can be up to 2 times higher thanthe synthetic jet. The dual synthetic jets actuator, which works with 1 or 2 times of thecharacteristics frequency of the cross-flow and with higher momentum coefficient, hasbetter ability to improve the aerodynamic characteristics of the airfoil.更多还原