翟志刚, 郭旭, 司廷. 激波冲击锯齿形界面的气泡竞争实验研究[J]. 空气动力学学报, 2020, 38(2): 339-347. DOI: 10.7638/kqdlxxb-2020.0020
引用本文: 翟志刚, 郭旭, 司廷. 激波冲击锯齿形界面的气泡竞争实验研究[J]. 空气动力学学报, 2020, 38(2): 339-347. DOI: 10.7638/kqdlxxb-2020.0020
ZHAI Zhigang, GUO Xu, SI Ting. Experimental study on bubble competition of shock-accelerated saw-tooth interface[J]. ACTA AERODYNAMICA SINICA, 2020, 38(2): 339-347. DOI: 10.7638/kqdlxxb-2020.0020
Citation: ZHAI Zhigang, GUO Xu, SI Ting. Experimental study on bubble competition of shock-accelerated saw-tooth interface[J]. ACTA AERODYNAMICA SINICA, 2020, 38(2): 339-347. DOI: 10.7638/kqdlxxb-2020.0020

激波冲击锯齿形界面的气泡竞争实验研究

Experimental study on bubble competition of shock-accelerated saw-tooth interface

  • 摘要: 通过实验在激波管中研究了平面激波冲击锯齿形界面的流动不稳定性演化过程,重点关注锯齿形界面初始顶角角度对气泡竞争的影响。利用肥皂膜技术生成初始气体界面,并采用高速摄影结合纹影方法对波后流场进行观测。结果表明:在界面发展早期,大、小界面几乎独立发展,说明气泡竞争在早期不起作用;随着时间发展,气泡竞争起作用,且随着锯齿形界面角度改变而变化,角度越小,界面上产生的斜压涡量越大,界面发展越快,气泡竞争越早出现且作用越显著。气泡竞争能够促进大气泡、抑制小气泡的振幅增长,且对小气泡的影响更大。气泡竞争同时会导致尖钉结构扭曲,进而改变界面总体振幅。气泡头部位移差在进入非线性增长之前会经历两个线性阶段,且第二个线性增长率较小,表明非线性效应在该阶段具有重要作用,大气泡受到非线性效应的影响更大。不同条件下的气泡位移差无法归一化,说明初始顶角角度对气泡竞争和界面演化具有重要影响。

     

    Abstract: The flow instability development of a shock-accelerated saw-tooth interface has been studied in shock tube experiments, and the effect of initial vertex angle on the bubble competition is highlighted. The soap film technique is adopted to generate the initial saw-tooth gaseous interface, and the post-shock flow is captured by a high-speed video camera combined with the schlieren photography. The results show that at the very early stages, the large and small bubbles develop independently, implying that the bubble competition does not work initially. As the time goes by, the bubble competition plays an important role, and behaves differently for the saw-tooth interface with different vertex angles. As the vertex angle reduces, more baroclinic vorticity is deposited with the interface developing more quickly, and the bubble competition occurs earlier and becomes more significant. The bubble competition promotes the large bubble growth, whereas it inhibits the small bubble growth. Relatively, the bubble competition has a more prominent effect on the small bubble growth. Moreover, the bubble competition will distort the spike head, which will affect the total interface amplitude growth. The bubble front difference seems to experience two linear stages before it enters nonlinear stage. The growth rate in the second linear stage is smaller than that in the first linear stage, indicating that the nonlinearity exerts a significant effect to the flow in the second stage. Specifically, the nonlinearity plays a more significant effect on the large bubble growth. The bubble front difference cannot collapse in dimensionless form, which means the vertex angle has a great influence on the saw-tooth interface development.

     

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