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1.
反射激波冲击重气柱的RM不稳定性数值研究   总被引:1,自引:0,他引:1  
数值研究了二维气柱在入射激波以及反射激波作用下的Richtmyer-Meshkov(RM)不稳定性发展规律,采用有限体积法结合网格自适应技术的VAS2D程序,精确刻画激波和界面的演化.入射平面激波的马赫数为1.2,气柱界面内气体为六氟化硫(SF6),环境气体为空气,激波管的尾端为固壁.通过改变气柱与尾端之间的距离调节反射激波再次作用已经变形的气柱的时间,获得不同时刻下已经变形的气柱形态、界面尺寸以及环量演化受到反射激波的影响.结果表明,反射激波再次作用气柱时,气柱所处发展阶段不同,界面演化规律以及环量随时间的变化也不相同,反射激波与气柱相互作用过程中的涡量产生和分布与无反射情况差异较大,揭示了不同情况下界面演化的物理机理.  相似文献
2.
We describe a laser absorption technique to obtain reasonably accurate density profiles within a shock-induced Richtmyer-Meshkov mixing zone. Assuming a small temperature variation through the probed region, a single wavelength absorption experiment only is needed. When this criterium is satisfied, the technique described represents a considerable simplification over the more generally required dual wavelength experiments. Received 4 May 1996 / Accepted 7 October 1996  相似文献
3.
Based on the previously formulated mathematical model of mechanics of a two-velocity two-temperature mixture of gases, the evolution of an initially disturbed mixing layer of two gases with different densities under the action of shock waves is considered in a two-dimensional unsteady approximation. Problems of interaction of shock waves with a sinusoidally disturbed diffuse layer are solved numerically. The predicted variation of the mixing-region width are in satisfactory agreement with experimental data. __________ Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 46, No. 3, pp. 3–11, May–June, 2005.  相似文献
4.
施红辉  卓启威 《力学学报》2007,39(3):417-421
使用矩形激波管,在马赫数分别为M=1.5和1.7的条件下实验研究了气/液界面上(即Atwood数A接近1时)由Richtmyer-Meshkov不稳定性引起的流体混合现象.得到了气/液界面上Richtmyer-Meshkov不稳定性后期流体混合区域宽度随时间的发展呈现出线性关系的结果,即h∝t.比较了不同马赫数和初始扰动下的发展情况,发现当马赫数增加时,同一时间混合区域宽度随之增加,混合区域宽度增长变快;而相比于波长差别不大的弱多模态初始扰动(无人为干扰界面),当界面初始扰动获得随机外界干扰时,界面混合区域具有较大的宽度以及增长速度.并且增加激波马赫数和初始扰动多模态性,流体混合程度更为剧烈.  相似文献
5.
Abstract. A new large cross-section shock tube has been developed in order to investigate different stages of the development of the Richtmyer-Meshkov instability and the instability-induced turbulent mixing. The main benefits of such a facility are that it allows, first, to create a free turbulent mixing with the knowledge of its initial conditions and, second, to follow different transition phases from the beginning to the fully developed turbulent stage. Received 10 May 2002 / Accepted 20 July 2002 Published online 4 February 2003 Correspondence to: L. Houas (e-mail: Lazhar.Houas@polytech.univ-mrs.fr)  相似文献
6.
采用基于有限体积法的二阶Godunov格式模拟了柱形密度交界面在同轴激波加速下的演化过程。得到了以下初步结果:在参数相同的情形下,内聚激波比中心爆炸波对界面的扰动更危险;内聚激波从轻质流体进入重质流体与从重质流体进入轻质流体相比,界面有更快的增长。周向波数大小对界面增长率有很大的影响,在计算的参数下,n=8~12有最大增长率,大于和小于这个范围的周向波长,增长率均明显减弱。  相似文献
7.
A constant temperature hot-wire anemometry method is applied to the study of mixing zones induced by the interaction of a shock wave with Mach number 1.25 in air with air/helium (heavy/light), air/argon or air/krypton (light/heavy) initially plane interfaces. The single wire gauge is positioned at various locations along the shock tube axis. At the present stage of our investigation, although the analysis of the hot-wire signal is not achieved yet, we report the interesting concept of using hot-wire anemometry as a diagnostic method for shock tube studies of the Richtmyer-Meshkov instability. Based on this preliminary work, we discuss prospective experimental signal conversion, in order to provide some new results for this field of investigation, in particular for resolving characteristics of the turbulent mixing zone which is of most interest. Received 3 August 2000 / Accepted 15 February 2001  相似文献
8.
B.P. Howell  G.J. Ball 《Shock Waves》2000,10(4):253-264
Mesh-induced errors at material interfaces are identified as a source of unphysical behaviour in Lagrangian numerical simulations of Richtmyer-Meshkov instability. The mesh geometry introduces interface perturbations with wavelengths of the same order as the mesh resolution. When a shock propagates through the interface, these perturbations can grow, severely contaminating the predicted interface development. Here an algorithm is presented which damps small-scale interface perturbations. A body force is applied at the interface which depends upon the disturbance amplitude and growth rate, and which resembles surface tension. Using this technique, qualitative improvements are obtained in Free-Lagrange simulations of single-mode Richtmyer-Meshkov instability. Growth rate behaviour and the evolution of the instability are seen to agree well with previously published results. Received 9 March 2000 / Accepted 30 May 2000  相似文献
9.
The effect of the thin membrane on the time evolution of the shock wave induced turbulent mixing between the two gases initially separated by it is investigated using two different sets of experiments. In the first set, in which a single-mode large-amplitude initial perturbation was studied, two gas combinations (air/SF and air/air) and two membrane thicknesses were used. The main conclusion of these experiments was that the tested membrane has a negligible effect on the evolution of the mixing zone, which evolves as predicted theoretically. In the second set, in which similar gas combinations and membrane thicknesses were used, small amplitude random-mode initial perturbation, caused by the membrane rupture, rather than the large amplitude single-mode initial perturbation used in the first set, was studied. The conclusions of these experiments were: (1) The membrane has a significant effect on the mixing zone during the initial stages of its growth. This has also been observed in the air/air experiment where theoretically no growth should exist. (2) The membrane effect on the late time evolution, where the mixing zone width has reached a relatively large-amplitude, was relatively small and in good agreement with full numerical simulations. The main conclusion from the present experiments is that the effect of the membrane is important only during the initial stages of the evolution (before the re-shock), when the perturbations have very small amplitudes, and is negligible when the perturbations reach relatively large amplitudes. Received 29 August 1998 / Accepted 25 December 1998  相似文献
10.
An experimental investigation on gaseous mixing zones originated from the Richtmyer-Meshkov instability has been undertaken in a square cross section shock tube. Mass concentration fields, of one of the two mixing constituents, have been determined within the mixing zone when the shock wave passes from the heavy gas to the light one, from one gas to an other of close density, and from the light gas to the heavy one. Results have been obtained before and after the coming back of the reflected shock wave. The diagnostic method is based on the infrared absorption of one of the two constituents of the mixing zone. It is shown that the mixing zone is strongly deformed by the wall boundary layer. The consequence is the presence of strong gradients of concentration in the direction perpendicular to the shock wave propagation. Finally, it is pointed out that the mixing goes more homogeneous when the Atwood number tends to zero.  相似文献
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