Large-eddy simulation of laminar transonic buffet
Large-eddy simulation of laminar transonic buffet
复制标题
层流跨音速抖振的大涡模拟
DOI：
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发表时间：
2018
影响因子：
3.7
通讯作者：
V. Brion
中科院分区：
文献类型：
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作者：
J. Dandois;I. Mary;V. Brion
马赫数M=0.735，攻角为4，雷诺数Re_{c}=3时翼型层流跨音速抖振的大涡模拟 10^{6}$已完成。边界层是层流的冲击脚和层流/湍流过渡发生在分离泡在冲击脚。与紊流情况相反，紊流情况下壁面压力谱的特征是在低频处有明显的峰值（St=fcdot c/U_{infty }simeq 0.06{-}0.07$，其中St为Strouhal数，f为激波振荡频率，c为弦长，U_{infty }$为自由流速度），在层流情况下，也有明显的峰值，但频率高得多（St=1.2）。激波振荡幅度也较低：层流情况下为弦的6%，并限于激波根部区域，而湍流情况下为整个激波振荡和间歇边界层分离和再附着的20%。通过对相平均场的分析，可以把层流跨音速抖振的频率同与旋涡脱落机制有关的分离气泡呼吸现象联系起来。这些涡旋以U_{c}/U_{infty }simeq 0.4$（其中U_{c}$是对流速度）对流。本文的主要发现是，在层流状态下的激波振荡的较高频率是由于一个不同的机制比在湍流之一：层流跨音速抖振是由于分离气泡呼吸现象发生在激波脚。
A large-eddy simulation of laminar transonic buffet on an airfoil at a Mach number $M=0.735$ , an angle of attack $unicode[STIX]{x1D6FC}=4^{circ }$ , a Reynolds number $Re_{c}=3 imes 10^{6}$ has been carried out. The boundary layer is laminar up to the shock foot and laminar/turbulent transition occurs in the separation bubble at the shock foot. Contrary to the turbulent case for which wall pressure spectra are characterised by well-marked peaks at low frequencies ( $St=fcdot c/U_{infty }simeq 0.06{-}0.07$ , where $St$ is the Strouhal number, $f$ the shock oscillation frequency, $c$ the chord length and $U_{infty }$ the free-stream velocity), in the laminar case, there are also well-marked peaks but at a much higher frequency ( $St=1.2$ ). The shock oscillation amplitude is also lower: 6 % of chord and limited to the shock foot area in the laminar case instead of 20 % with a whole shock oscillation and intermittent boundary layer separation and reattachment in the turbulent case. The analysis of the phase-averaged fields allowed linking of the frequency of the laminar transonic buffet to a separation bubble breathing phenomenon associated with a vortex shedding mechanism. These vortices are convected at $U_{c}/U_{infty }simeq 0.4$ (where $U_{c}$ is the convection velocity). The main finding of the present paper is that the higher frequency of the shock oscillation in the laminar regime is due to a different mechanism than in the turbulent one: laminar transonic buffet is due to a separation bubble breathing phenomenon occurring at the shock foot.