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M. Brouillette 《Shock Waves》2003,13(1):3-12
We present a model for the effects of scale, via molecular diffusion phenomena, on the generation and propagation of shock waves. A simple parametrization of the shear stresses and heat flux at the wall leads to the determination of new jump conditions, which show that, for a given wave Mach number at small scales, the resulting particle velocities are lower but the pressures are higher. Also, the model predicts that the flow at small scale is isothermal and that the minimum wave velocity can be subsonic. Experiments with a miniature shock tube using low pressures to simulate the effects of small scale have shown qualitative agreement with the proposed model. In fact, the effects of scale appear even more important than what has been incorporated in the model.PACS:
47.40.-xReceived: 14 November 2002, Accepted: 2 April 2003, Published online: 18 June 2003 相似文献
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为研究爆炸应力波与裂纹相互作用机理,利用透射式爆炸动态焦散线光学实验系统研究了预制水平静态裂纹和切缝药包炮孔爆破产生的水平运动裂纹受正入射爆炸动载作用后动态特性的变化规律。结果表明:正入射爆炸应力波与静止裂纹作用时,爆炸应力波P波使得裂纹先闭合后张开,S波在裂纹壁面形成波浪状散斑上下交替向外扩展;运动裂纹尖端应力场对静止裂纹的起裂和扩展有重要影响。后爆孔爆炸应力波对先爆孔产生的水平定向运动裂纹尖端动力学特性影响显著。当爆炸应力波与运动裂纹同向时,P波使得裂纹扩展速度和应力强度因子KI^d先减小后增大,S波促进了裂纹的扩展,波与裂纹作用之后,裂纹扩展速度增大;当爆炸应力波与运动裂纹反向时,P波抑制了运动裂纹的扩展,波与裂纹作用之后,裂纹扩展速度和应力强度因子KI^d均逐渐降低。 相似文献
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Using the weakly non-linear geometrical acoustics theory, we obtain the small amplitude high frequency asymptotic solution
to the basic equations in Eulerian coordinates governing one dimensional unsteady planar, spherically and cylindrically symmetric
flow in a reactive hydrodynamic medium. We derive the transport equations for the amplitudes of resonantly interacting waves.
The evolutionary behavior of non-resonant wave modes culminating into shock waves is also studied.
相似文献
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坑道内化爆冲击波的传播规律 总被引:40,自引:2,他引:40
装药在坑道内部爆炸时将产生沿坑道传播的空气冲击波,由于受到坑道洞壁的限制,空气冲击波在坑道内的传播规律异于在自由大气中的传播。利用三维数值模拟计算程序,对长坑道中的化爆流场进行了数值计算,归纳出空气冲击波沿坑道方向的传播规律。计算结果与试验结果符合较好。 相似文献
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The mitigating effect of a water wall on the generation and propagation of blast waves of a nearby explosive has been investigated
using a numerical approach. A multimaterial Eulerian finite element technique is used to study the influence of the design
parameters, such as the water-to-explosive weight ratio, the water wall thickness, the air-gap and the cover area ratio of
water on the effectiveness of the water mitigation concept. In the computational model, the detonation gases are modelled
with the standard Jones–Wilkins–Lee (JWL) equation of state. Water, on the other hand, is treated as a compressible fluid
with the Mie–Gruneisen equation of state model. The validity of the computational model is checked against a limited amount
of available experimental data, and the influence of mesh sizes on the convergence of results is also discussed. From the
results of the extensive numerical experiments, it is deduced that firstly, the presence of an air-gap reduces the effectiveness
of the water mitigator. Secondly, the higher the water-to-explosive weight ratio, the more significant is the reduction in
peak pressure of the explosion. Typically, water-to-explosive weight ratios in the range of 1–3 are found to be most practical.
PACS 47.40.-x; 47.40.Nm; 02.60.Cb
This paper was based on work that was presented at the 19th Interna-tional Colloquium on the Dynamics of Explosions and Reactive
Sys-tems, Hakone, Japan, July 27 - August 1, 2003 相似文献
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The solution of the problem of propagation of a wave in soils is presented for the case when the wave is produced by the detonation of a spherical charge of some explosive material (EM). The solution is obtained on a computer by the method of characteristics. The soils are regarded as multicomponent media consisting of solid particles, water, and air in conformity with the model proposed in [1, 2]. The dependence of the pressure, velocity of the particles, and the density in the wave front on the distance is determined; the variation of these parameters with time at fixed points of the medium is also determined. The results are compared with the results of tests [1, 2]. Their close agreement for different contents of the components indicates the applicability of the multicomponent model to soils. The limits of applicability of the model are determined. The propagation of a plane wave under the same conditions was investigated in [3]. 相似文献
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A. S. Fonarev 《Journal of Applied Mechanics and Technical Physics》1992,33(1):56-59
Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, No. 1, pp. 62–65, January–February, 1992. 相似文献
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Shock waves in aviation security and safety 总被引:2,自引:0,他引:2
Accident investigations such as of Pan Am 103 and TWA 800 reveal the key role of shock-wave propagation in destroying the
aircraft when an on-board explosion occurs. This paper surveys shock wave propagation inside an aircraft fuselage, caused
either by a terrorist device or by accident, and provides some new experimental results. While aircraft-hardening research
has been under way for more than a decade, no such experiments to date have used the crucial tool of high-speed optical imaging
to visualize shock motion. Here, Penn State's Full-Scale Schlieren flow visualization facility yields the first shock-motion
images in aviation security scenarios: 1) Explosions beneath full-size aircraft seats occupied by mannequins, 2) Explosions
inside partially-filled luggage containers, and 3) Luggage-container explosions resulting in hull-holing. Both single-frame
images and drum-camera movies are obtained. The implications of these results are discussed, though the overall topic must
still be considered in its infancy.
Received 22 July 2001 / Accepted 19 July 2002 Published online 4 November 2002
Correspondence to: G.S. Settles (e-mail: gss2@psu.edu)
An abridged version of this paper was presented at the 23rd International Symposium on Shock Waves at Fort Worth, Texas, from
July 22 to 27, 2001. 相似文献
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B. E. Gelfand A. M. Bartenev S. P. Medvedev A. N. Polenov S. V. Khomik M. Lenartz H. Grönig 《Shock Waves》1994,4(3):137-143
On the basis of numerical modeling specific features of shock wave reflections were analyzed. It was found, that after diaphragm rupture self-modeling pressure and velocity distributions nearby the shock front establish. But in some special cases the temperature behind the shock front can rise. This peculiarity should be taken into account when performing experiments with high reactive gaseous mixtures. The temperature on the shock front and the velocity gradient behind it are uniform in the case of strong blast wave reflections. This effect is observed in the zone with an elevated temperature profile behind the incident blast wave. The reflected triangular waves conserve a quasi-self-modeling character by pressure. Typical experiments were carried out to verify the theoretical predictions. The effects of reflected wave acceleration in the case of triangular waves and the self-similar character of the pressure profiles were observed.This article was processed using Springer-Verlag TEX Shock Waves macro package 1.0 and the AMS fonts, developed by the American Mathematical Society. 相似文献
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Matthew F. McCarthy 《Archive for Rational Mechanics and Analysis》1991,115(2):167-178
A continuum theory for the distribution of incompressible particles in an incompressible fluid is employed to study the behaviour of plane shock waves in a particulate suspension. An expression is derived for the speed of displacement in terms of the jump in the volume fraction of one of the constituents across the shock. A differential equation is derived to govern the evolutionary behaviour of the shock wave propagating into a region which is in a uniform equilibrium state before the arrival of the shock wave. The implications of this equation are examined in detail. 相似文献
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Summary The thermodynamic theory of shock waves in incompressible elastic solids is reviewed, and the Hugoniot relation and the propagation condition for the shock speed are derived. Expanding the equations, for weak shock waves, in powers of the shock strength some well-known results of gasdynamics are generalized to the dynamics of shock waves in incompressible elastic media.
With 2 figures 相似文献
Zusammenfassung Die thermodynamische Theorie der Stoßwellen in inkompressiblen elastischen Körpern wird zusammenfassend dargestellt, die Hugoniot-Relation und die Ausbreitungsbedingung für die Stoßgeschwindigkeit werden abgeleitet. Durch Reihenentwicklung nach Potenzen der Stoßstärke werden für schwache Stoßwellen einige bekannte Ergebnisse der Gasdynamik für die Dynamik der Stoßwellen in inkompressiblen elastischen Medien verallgemeinert.
With 2 figures 相似文献