【作者】 王登攀；

【导师】 夏智勋；

【作者基本信息】 国防科学技术大学 ， 航空宇航科学与技术， 2012， 博士

【摘要】 超声速/高超声速飞行器内、外流场中普遍存在着部件之间的耦合影响，部件之间相互干扰涉及多种复杂流动现象，如边界层转捩、复杂激波干扰、激波诱导边界层分离、再附激波与尾迹的相互作用等，对飞行器的气动、动力和控制等性能具有十分重要的影响。这些复杂流场结构体现了典型壁面突起物绕流特征，是当前流动控制研究中的热点和难点问题，因此，相关流场的精细结构与动力学特性研究，具有重要的理论研究价值和广泛的工程应用价值。超声速壁面涡流发生器绕流流场受到可压缩性、湍流、大尺度涡结构、激波、滑移线等强间断和强非线性因素的影响，导致绕流流场精细结构的高分辨率数值模拟和测量十分困难。本文采用高分辨率NPLS技术，从涡结构、速度场和密度场三个方面，分别对三角翼、圆柱和半球三种构型附壁涡流发生器的超声速绕流流场的空间精细结构、时间演化特征及动力学特性进行了深入研究。由于涡流发生器附近流场区域的流动结构变化快、时间相关性差，某些特征通过实验直接辨识存在一定的困难，本文结合数值模拟技术与实验结果进行了相互验证。多视角和多分辨率NPLS图像再现了超声速壁面涡流发生器绕流流场的复杂结构。超声速气流与不同构型涡流发生器相互作用，可能产生前缘三维压缩激波、三维脱体激波、再附激波、小激波等复杂波系结构，及上游分离区、壁面三维拓扑结构、下游回流区、尾迹和流向涡等复杂流动结构。基于时间相关的NPLS图像，系统研究和分析了不同构型涡流发生器绕流流场结构随时间的演化特征；根据不同流向和展向平面绕流流场结构的时空结构特征，发现了不同构型涡流发生器涡结构的周期性脱落模式；建立了不同构型涡流发生器绕流流场的激波结构和拟序结构模型。超声速绕流流场一般具有较大的速度梯度，特别是激波前后会存在间断，相应的速度场测量极具挑战性。本文利用NPLS系统中纳米粒子的高动态响应特性，结合当前PIV测速技术，对超声速三角翼、圆柱和半球三种涡流发生器绕流速度场进行了深入研究。不同流向切面的速度分布表明，不同构型超声速附壁涡流发生器绕流的速度场结构及其动力学成因存在较大的区别；发现了尾流区拟序结构所表征的涡结构特征，并据此建立了尾流区拟序结构模型。基于NPLS图像，实现了对三种构型涡流发生器的超声速绕流密度场的瞬态测量。根据相应绕流流场的密度分布情况，发现超声速绕流流场在激波前后、涡流发生器附近、主流与边界层和尾流区拟序涡结构之间存在较大的密度梯度。分别对尾流涡结构和壁面效应对密度脉动的作用效应及密度脉动的非定常性进行了研究，并由此分析了激波结构、尾流区拟序涡结构对超声速绕流流场密度脉动造成的影响；频域特征分析表明尾流区大尺度涡结构是尾流区拟序涡结构质量、动量和能量的主要载体，主导着与高密度高速主流的质量、动量和能量的交换，其沿流向的发展和演化是导致超声速壁面涡流发生器尾流区发生密度脉动的主要因素。论文研究过程中，提出了基于NPLS技术的超声速附壁涡流发生器绕流密度场和速度场的测量方法；发现了超声速附壁涡流发生器绕流流场的三维激波/边界层相互干扰、波-涡相互作用和尾流区拟序结构等复杂流场结构；建立了超声速附壁涡流发生器绕流流场激波结构和尾流区的流动结构模型，对利用涡流发生器干扰和控制超声速流场具有重要的意义。由于绕流流场结构比较复杂，需要采用更高分辨率的测量技术，对绕流流场更加精细的结构特征和复杂动力学过程进行更加深入的研究。更多还原

【Abstract】 The mutual interference between the components of a vehicle in the supersonic orhypersonic flow field generates complex flow field structures, which contain theboundary layer transition, the interaction between shock waves, the boundary layerseparation, the reattached shock wave and the wake. Controlling and disturbing of theflow field by using vortex generator has been becoming a research hotspot but alsodifficulty in the study of the flow control. The study of the fine structures and dynamicbehaviors of the flow field has an important theoretical and engineering practical value.The influences of strong nonlinearity and diffusion factors, such as compressibility,turbulence, large scale structure, shock waves and slip line, make it difficult to study thefine structures of supersonic flow over a protuberance by means of high resolutionnumerical simulation and measurement. Based on the high resolution NPLS(Nano-tracer Planar Laser Scattering) technique, the spatial fine structures and temporalevolution characteristics of supersonic flow over various models (the delta wing, thecylinder and the hemisphere) on the flat plate were studied. The distortion of the flowstructures is rapider and the time correlation is worse near the vortex generators.Considering the difficulty of identifying the evolutionary characteristics of the flowstructures only using the experimental images, the method of numerical simulation isused in the thesis to mutually verify the results with the experimental.The complex flow field structures of supersonic flow over the varied vortexgenerator on the flate plate were observed based on the multi-view and multi-resolutionNPLS images, which contain the three-dimensional detached shock wave, the separationregion, the recirculating region in the downstream, the reattached shock wave, the wakeand so on. Based on the time correlation NPLS images, the temporal evolutioncharacteristics of supersonic flow over the various vortex generators weresystematically studied. According to the space-time structure characteristics of the flowfield, the modes of the vortexes shedding off were discovered. Naturally the shock wavestructures and the vortex structure modes in the wake flow were modeled.In general, the supersonic flow over a protuberance possesses the characteristics oflarger velocity gradient. The disconnected will be generated when the supersonic flowpasses through the shock wave, which makes the velocity field measurement verydifficult. Here, the high dynamic response characteristics of nanoparticles of NPLSsystem were used and associate the PIV (Particle Image Velocimetry) technique toprofoundly study the velocity distribution of supersonic flow over various models. Theanalysis of the velocity distribution at the different streamwise planes indicates that thevelocity field and the dynamics origin are different. According to the measurementresults of supersonic PIV in the streamwise planes at different positions, the velocity field structures of supersonic flow over the various vortex generators on the wall wereprofoundly studied. The vortex structure characteristics of the coherent structure werediscovered. And the mode of the coherent structures in the wake was modeled.The transient measurement of the density field on the supersonic flow over thevaried vortex generators was achieved. According to the density distributioncharacteristics of the flow field, a larger density gradient occurs in front and back of theshock waves, between the main stream flow and boundary layer/coherent structures inthe wake flow and in the vicinity of the vortex generators. The influences of the vortexstructures and the wall on the density fluctuation were studied. And the unsteady of thedensity fluctuation was also studied. Consequently the influences of the shock wavesand the coherent structures on the density fluctuation were analyzed. The spectrumanalysis indicates the large-scale vortex structures are the main carrier of mass,momentum and energy in the wake flow, and predominates the exchange of thembetween the main stream flow and the coherent structures. The evolution of thelarge-scale vortex structures is the major factor of the density fluctuation in the wakeflow.Based on the NPLS technique, the method of measuring the distribution of thevelocity and density on the supersonic flow over a vortex generator was put forward.The complex flow structures, such as the mutual interference between thethree-dimensional shock waves and the boundary layer, the interaction between wavesand vortexes, and the coherent structure in the wake flow, were discovered. And themodes of shock waves and flow structures in the wake flow were modeled. It ismeaningful to achieve the control and disturbance of the flow field by using vortexgenerator. Due to the complexity of supersonic flow over a vortex generator, it isnecessary to study further into the finer structures characteristics and the complexdynamic behavior.更多还原