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991.
G. V. Belyakov A. A. Charakhch'yan 《Journal of Applied Mechanics and Technical Physics》2003,44(2):243-248
Several variants of the problem of heating a compressible liquid by a timeindependent heat flux are numerically studied. It is shown that, after a certain time, the pressure everywhere behind the shock wave differs only little from some constant value. Approximate analytical formulas are obtained, which demonstrate independence of pressure of thermal conductivity and some other features of the relation between the pressure and the heatflux intensity. Several examples are given, which confirm the adequacy of formulas to numerical solutions of the problem. 相似文献
992.
Shock wave interaction with a sphere is one of the benchmark tests in shock dynamics. However, unlike wind tunnel experiments, unsteady drag force on a sphere installed in a shock tube have not been measured quantitatively. This paper presents an experimental and numerical study of the unsteady drag force acting on a 80 mm diameter sphere which was vertically suspended in a 300 mm x 300 mm vertical shock tube and loaded with a planar shock wave of M
s
= 1.22 in air. The drag force history on the sphere was measured by an accelerometer installed in it. Accelerometer output signals were subjected to deconvolution data processing, producing a drag history comparable to that obtained by solving numerically the Navier-Stokes equations. A good agreement was obtained between the measured and computed drag force histories. In order to interpret the interaction of shock wave over the sphere, high speed video recordings and double exposure holographic interferometric observations were also conducted. It was found that the maximum drag force appeared not at the time instant when the shock arrived at the equator of the sphere, but at some earlier time before the transition of the reflected shock wave from regular to Mach reflection took place. A negative value of the drag force was observed, even though for a very short duration of time, when the Mach stem of the transmitted shock wave relfected and focused at the rear stagnation point of the sphere.Received: 31 March 2003, Accepted: 7 July 2003, Published online: 2 September 2003 相似文献
993.
T. Tominaga A. Nakagawa T. Hirano J. Sato K. Kato S. H. R. Hosseini K. Takayama 《Shock Waves》2006,15(1):55-67
Paper deals with applications of underwater shock waves to medicine. A historical development of underwater shock wave generation by using pulsed Ho:YAG laser beam irradiation in water is briefly described and an overview is given regarding potential applications of shock waves to neuro-surgery. The laser beam irradiation in a liquid-filled catheter produces water vapor bubble and shock waves intermittently produces micro-liquid jets in a controlled fashion from the exit of the catheter. Correlations between shock dynamics and bubble dynamics are emphasized. To optimize the jet motion, results of basic parametric studies are briefly presented. The liquid jet discharged from the catheter exit has an impulse high enough to clearly exhibit effectiveness for various medical purposes. In liquid jets we observed reasonably strong shock waves and hence invented a compact shock generator aiming to apply to microsurgery. We applied it to a rat's bone window and developed an effective method of brain protection against shock loading. The insertion of Gore-Tex® sheet is found to attenuate shock waves drastically even for very short stand off distance and its physical mechanism is clarified. The laser-induced liquid jet (LILJ) is successfully applied to soft tissue dissection. Animal experiments were performed and results of histological observations are presented in details. Results of animal experiments revealed that LILJ can sharply dissect soft tissue with a minimum amount of liquid consumption, while blood vessels larger than 0.2 mm in diameter are preserved. Shock waves and LILJ have a potential to be indispensable tools in neuro-surgery.This paper was based on work that was presented at the 2nd International Symposium on Interdisciplinary Shock Wave Research, Sendai, Japan, March 1–3, 2005.Communicated by K. Takayama
PACS 42.62.Be, 47.40.-x, 42.62.-b 相似文献
994.
995.
The weak Mach reflection phenomenon has been analyzed by applying both the shock dynamics approach and the disturbance propagation concept. The analysis which is based on modified Whitham's ray shock theory results in analytical expressions for the triple point trajectory angle,, and the shape of the curved Mach stem, which are functions of the incident shock wave Mach number,M
i, and the reflecting wedge angle,
w. The analytical results were found to be in good agreement with experimental results.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
996.
空气冲击波作用下人的安全距离 总被引:7,自引:1,他引:7
为了解决空气冲击波作用下人的安全距离问题,我们进行了1~10~5kg梯恩梯炸药爆炸情况下动物(羊、狗、兔)的试验。同时根据试验求得的各种爆炸条件下空气冲击波的传播规律,通过对炸药爆炸事故人伤亡情况的调查及对动物试验数据的分析,确定出人在空气冲击波作用下的安全距离。 相似文献
997.
利用激波管中波系间的相互干扰,实验模拟了爆炸波对水汽的作用,并通过光学测试方法,对水汽同质核化、凝结非定常瞬态变化过程进行了测定.结果表明:在爆炸波强度较弱时,水汽不发生凝结;而在一定强度爆炸波后的非定常流场中,水汽会发生同质核化、凝结.这说明较强爆炸波后的绝热冷却过程可以使水汽发生相变 相似文献
998.
999.
1000.
为了评估高温气冷核反应堆热交换器H2泄漏、爆炸的安全性,研究含内构件管道的H2/空气爆燃传播现象,建造了几何相似、尺寸相同的实验管道(真空筒)。分别充入不同初压和当量比H2/空气混合物,在真空筒顶部点火并引发爆燃,利用多通道瞬态压力测量和数据采集系统,记录各测点压力时间曲线。结果表明:对化学计量比H2/空气混合物,在慢化剂室和真空筒顶部空间产生爆燃,邻近测点的压力时间曲线显示了冲击波特征。该冲击波通过慢化剂室和真空筒侧壁的狭缝(2.5 mm),进入含内构件的扩张管道并形成爆燃。冲击波在真空筒端部反射、向后传播并与火焰相互作用,爆炸流场波系复杂。对富油和低初压化学计量比混合物,在慢化剂室和真空筒顶部空间产生燃烧,高温富油燃气的压力上升速率较慢。当燃气通过上述狭缝时,在真空筒突扩空间内再次点火并形成较强爆燃,压力时间曲线显示了冲击波特征及其在端面的反射。 相似文献