【作者】 陈逖；

【导师】 刘卫东；

【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】 本文建立了一套适用于超声速壁面湍流流动的数值模拟方法，建设了一座自由射流实验系统，采用上述数值模拟方法对高超声速进气道中的激波/湍流边界层干扰现象和射流式涡流发生器对边界层分离区的控制作用进行了研究，并在自由射流实验系统上进行了实验验证。构造了一种基于低扩散通量分裂方法的WENO格式，通过对Riemann问题的求解发现该格式对激波和膨胀波的分辨率高于传统的、基于Lax-Fridrichs分裂的WENO格式。建立了用于超声速壁面湍流计算的混合大涡/雷诺平均Navier-Stokes（混合LES/RANS）模拟方法并对其进行了理论分析，通过对高雷诺数超声速湍流边界的计算研究了空间维数、混合函数的过渡特性和网格分辨率的影响。发现二维计算会使入口边界层的平均参数发生不合理的漂移；RANS区域和LES区域的转换位置应当设置在对数层和尾迹层过渡区，且转换区域应当尽量窄；流向及展向的网格尺度和Escudier混合长相当时就能够获取精度较好的雷诺应力。建立了用于生成可压缩壁面湍流入口脉动边界条件的“回收/调节”方法，通过对超声速湍流边界层的计算分析了展向宽度、回收距离、网格分辨率和Klebanoff间歇函数的影响。发现展向宽度太小会导致入口边界层的平均参数发生漂移；回收距离过短会使流场中出现不合理的周期性涡结构和流向速度条带结构；在足够的网格分辨率下，“回收/调节”方法能够获得精度较高的雷诺应力；Klebanoff间歇函数可以合理地抑制边界层外层的脉动，提高雷诺应力的计算精度。建立了两种超声速湍流边界层混合LES/RANS模拟的初始化方法，一种是基于湍流边界层理论的相似变换方法，另一种是合成湍流方法，通过对超声速湍流边界层的计算发现相似变换方法构造的初场和N-S方程的相容性更好，从初场计算过渡至充分发展的湍流流场的时间大大短于合成湍流方法。对高超声速进气道中的流动问题进行了简化和计算，包括二维进气道的不启动流场和两种构型的交叉激波/湍流边界层干扰问题，发现在所研究的三个流动问题中分离区和分离激波存在大时空尺度的低频运动，其主频和理论值吻合；二维进气道可能在启动与不启动之间出现间歇性的转换，隔离段的流动呈现与分离区一致的低频特性；在交叉激波/湍流边界层干扰中，随着干扰强度的增大，分离区和分离激波的运动幅度会显著增大。对超声速边界层和射流涡流发生器的相互作用进行了研究，获取了精细的流场结构，包括不对称的弓形激波、桶状激波和流向涡对结构。射流倾斜一侧的流向涡生成较早，涡核离壁面较近，持续距离较短，搅拌作用较强，另一侧流向涡生成较晚，涡核离壁面较远，持续距离较长，搅拌作用较弱。射流可以增大边界层内层的能量。研究了射流对二维边界层分离区的控制作用，结果表明增大喷注压力可以减小分离区，但并不是越大越好，而是存在一个最佳值；俯仰角为45°时效果较好，偏航角影响较小，射流和分离区之间的距离应当足够长。对双孔射流阵和超声速边界层的相互作用进行了研究，发现两个射流孔的间距对下游的流场影响很大，间距较小会使得两股射流产生的流向涡结构相互挤压，导致耗散加快，带来不利影响。研究了双孔射流对二维边界层分离区的控制作用，发现同向喷射的效果优于反向喷射。更多还原

【Abstract】 A set of numerical simulation method for supersonic wall-bounded turbulent flowswere studied and a freejet experimental facility was built in the present work.Shock/boundary layer interactions and the control of boundary-layer separation withvortex generator jets in hypersonic inlets were investigated and experimental validationswere performed.A WENO scheme based on low diffusion flux splitting method was constructedand used in the calculation of Riemann problem. The results showed it has betterresolution than the traditional WENO scheme based on Lax-Fridrichs splitting.A hybrid Large-Eddy/Reynolds-Averaged Navier-Stokes(hybrid LES/RANS)method for supersonic wall-bounded turbulent flows was established and analyzedtheoretically. In the calculation of a high Reynolds-number supersonic turbulentboundary-layer, geometric dimensions, grid resolution and the transition characteristicsof the blending function were considered. The results showed that the mean parametersof the inflow boundary-layer shifted unreasonably in two-dimensional calculation. TheRANS to LES transition zone should be placed in the interface region of logarithmiclayer and wake layer and the transition zone should be narrow. Acceptable predictionsof Reynolds stress can be obtained if streamwise and spanwise grid spacings are scaledaccording to the Escudier mixing length.A recycling/rescaling method for generating turbulent inflow flucutations wasestablished. The effects of spanwise width, recycling distance and grid resolution werestudied in the calculation of a supersonic turbulent boundary-layer. The results showedthat inadequate spanwise width led to shift of the mean inflow parameters.Unreasonable periodic vortex structures and streaks of streamwise velocity appearedwith inadequate recycling distance. Good predictions of Reynolds stress could beobtained by the recycling/rescaling method with enough grid resolution. Klebanoffintermittency function helped attenuate fluctuations in the outer layer of theboundary-layer and thus improved the calculation of Reynolds stress.Flow fileds in hypesonic inlets were simplified and calculated, including anunstarted flow field in a two-dimensional inlet and two crossing-shock/boundary-layerinteraction(CSBLI) cases. The results showed that the shock systems and separationzones in all three cases exhibited low-frequency motions in large scale of time andspace and their main frequencies were close to theoretic values. In the two-dimensionalinlet case, the flow field might be switch between start and unstart intermittently, andthe flow in the isolator exhibited similar low-frequency characteristic in the separationregion. In the two CSBLI cases, the motion of the shock system and separation regionexhibited in larger scale when interaction strength increased. The interaction of between vortex generator jet and supersonic boundary-layer wasinvestigated. The flow field includes asymmetric bow shock, barrel shock andstreamwise vortex pairs. The streamwise vortex on the side which the jet inclined to wasstronger, closer to the wall, generated earlier and existed with shorter duration than itscounterparts on the other side of the jet. The control effect of a two-dimensionalboundary-layer separation zone with a vortex generator was validated. The resultsshowed that increasing pressure of the jet makes the separation zone become smaller.An optimal pitch angle is close to45degrees and the change of yaw angle seemsineffective to the flow field. The distance from the jet to the separation region should belong enough for the streamwise vortexes to play a role on the separation. Double jetswith inadequate distance of each other promoted the interaction of the streamwisevortexes and make them dissipate fastser. Co-direction jets did a better job thancounter-direction jet in the control of the separation zone.更多还原