共查询到19条相似文献,搜索用时 93 毫秒
1.
利用水平圆柱形激波管对激波驱动的可压缩性气固两相流进行了试验研究.利用压电式压力传感器、电荷放大器、示波器及计算机组成的压力信号测试系统, 对激波与颗粒作用前后的气相参数进行测量及分析. 试验中测得了激波在管中的传播速度, 波后气流的压力, 反射激波、透射激波的压力和速度等. 分别考察颗粒、装载比、驱动气源以及入射激波马赫数等因素的差异对气相参数的影响.试验结果表明: 激波与颗粒群相互作用时, 会产生反射激波和透射激波,其强度与驱动气源、颗粒大小、颗粒装载比等参数有关;激波衰减率随着装载比、马赫数的增大而减小. 研究指出,在颗粒群被激波加速的初始阶段, 颗粒间的弹性碰撞起着重要的作用. 相似文献
2.
利用水平圆柱形激波管对激波驱动的可压缩性气固两相流进行了试验研究.
利用压电式压力传感器、电荷放大器、示波器及计算机组成的压力信号测试系统, 对激波
与颗粒作用前后的气相参数进行测量及分析. 试验中测得了激波在管中的传播速
度, 波后气流的压力, 反射激波、透射激波的压力和速度等. 分别考察颗粒、装载
比、驱动气源以及入射激波马赫数等因素的差异对气相参数的影响.
试验结果表明: 激波与颗粒群相互作用时, 会产生反射激波和透射激波,
其强度与驱动气源、颗粒大小、颗粒装载比等参数有关;
激波衰减率随着装载比、马赫数的增大而减小. 研究指出,
在颗粒群被激波加速的初始阶段, 颗粒间的弹性碰撞起着重要的作用. 相似文献
3.
激波与可运动颗粒群相互作用反射与透射机理实验研究 总被引:1,自引:0,他引:1
对水平圆柱形激波管内可压缩性气体与颗粒群的相互作用进行了实验研究与理论分析。利用由压力传感器、信号放大器、示波器和计算机组成的压力测量系统对激波与颗粒群作用时的动态压力进行了测量。发现激波管内发生的是一个复杂的过程,包括激波与颗粒群作用时伴随了激波和膨胀波的反射与透射现象、激波和膨胀波与接触面的干涉、以及激波从激波管端壁的反射等现象。当颗粒装载比α=1时,透射激波被直径为6mm的颗粒群衍射并且有膨胀波紧随其后,因此由透射激波引起的第一个压力峰急剧下降。颗粒装载比和颗粒直径影响透射激波的衍射和衰减。 相似文献
4.
取稀颗粒群气固两相耦合的双流体简化模型,采用高解数值方法研究了收敛柱激波在粉尘气体中的传播和波后流场特性。通过与纯气体情况比较,揭示了固体颗粒出现对收敛柱激波传播特性的影响。 相似文献
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建立了用于模拟入射激波后可燃粉尘颗粒点火的一维非定常两相化学反应流模型,该模型考虑了气固两相间的相互作用、粉尘颗粒的加速、加热和化学反应。粉尘颗粒着火前的化学反应用发生在颗粒外表面和内孔表面的非均相反应描述,颗粒内部的温度变化用一含有化学反应源项的非稳态热传导方程来描述,以颗粒外表面温度的突跃上升作为可燃粉尘颗粒点燃的着火条件。我们用该模型和PSIC方法,对由中等强度激波从纯气相传入煤粉-氧气混合物而引起的非定常两相流动现象,包括气固两相间的相互作用、粉尘颗粒的加速、加热以及点火过程进行了数值研究,计算了对应于不同载荷比、马赫数为4~5的入射激波后煤尘颗粒的点火延迟时间,分析了由于可燃粉尘颗粒的存在,入射激波及波后气固两相流动参数的变化规律。数值计算结果与实验数据符合较好。文中建立的模型和所用的基于PSIC算法的数值方法,用最自然的方式描述气固两相流动,即用连续流模型(欧拉方程)描述输运相(气相)的流动,用轨道颗粒模型(拉格朗日方程)描述分散相(颗粒相)的运动。用这种方法模拟含尘介质中激波后颗粒的点火是很有效的,它可以清楚地确定哪一个颗粒群最先着火,它的初始位置以及在整个点火延迟时间内 相似文献
7.
对气、固两相正激波松弛流动进行了数值研究,方程中考虑了压力梯度及非匀速运动引起的附加质量力。给出了完整的计算方法,对三种不同固相容积比、不同固相颗粒直径和不同马赫数分别进行了数值计算,所得计算结果给出了气、固两相的速度、温度、压力、密度、固相容积比及熵值沿流向分布情况。文章对气、固两相参数在松弛区中的变化规律进行了讨论。 相似文献
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对气、固两相正激波松弛流动进行了数值研究,方程中考虑了压力梯度及非匀速运动引起的附加质量力。给出了完整的计算方法,对三种不同固相容积比、不同固相颗粒直径和不同马赫数分别进行了数值计算,所得计算结果给出了气、固两相的速度、温度、压力、密度、固相容积比及熵值沿流向分布情况。文章对气、固两相参数在松弛区中的变化规律进行了讨论。 相似文献
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A dense packed sand wall is impacted by a planar shock wave in a horizontal shock tube to study the shock-sand wall interaction. The incident shock Mach number ranges from 2.18 to 2.38. A novel device for actively rupturing diaphragm is designed for the driver section of the shock tube. An apparatus for loading particles is machined by the electrical discharge cutting technique to create a dense packed particle wall. High-speed schlieren imaging system and synchronized pressure measurement system are used together to capture the wave structures and particle cloud velocity. The dynamic evolution model from dense packed particles to dense gas–solid cloud at the initial driving stage is established. The blockage and permeation effects of the sand wall work together and influence each other. The high pressure gas behind the incident shock wave blocked by the sand wall pushes the upstream front of the wall forward like a piston. Meanwhile, the high speed gas permeating through the sand wall drags the sands of the most downstream layer forward. The incident shock strength, initial sand wall thickness and particle diameter are varied respectively to investigate the shock attenuation and the wall acceleration. Increasing the sands diameter or mixing in small diameter sands can significantly attenuate the incident shock. The smaller particles or the particles in thinner wall can be dispersed into a larger range in the process of transform from dense packed particles to dense gas–solid cloud. Moreover, the stronger incident shock can disperse the particles into a larger region. 相似文献
12.
Interaction of a shock wave with a system of motionless or relaxing particles is numerically simulated. Regimes of the gas flow around these particles are described, and the influence of the initial parameters of the examined phenomenon on the flow pattern is analyzed. The drag coefficient of particles is calculated as a function of the Mach number behind the shock wave at a fixed Reynolds number. The dynamics of heat exchange for particles of different sizes (10 μm–1 mm) is determined, and the laws of thermal relaxation after passing of a shock wave over the system of particles are found. The times of thermal and velocity relaxation of particles are estimated as functions of the Reynolds number, and the predicted relaxation time is compared with the corresponding empirical dependences. 相似文献
13.
铝颗粒在激波后气流作用下的点火 总被引:7,自引:1,他引:7
对铝颗粒在激波后气流作用下的点火进行了理论分析 ,用三个不同的判据得到铝颗粒点火的延时曲线并与实验进行了比较。理论分析结果表明 ,铝颗粒可以在远低于Al2 O3 的熔点被点火 ,甚至只要在铝的熔点时就被点火。提出的铝颗粒在温度达到铝的熔点且铝完全熔化时被点火这个判据在一些条件下与实验符合很好。如果铝颗粒表面的氧化层较厚 ,则点火温度为氧化铝的熔点。 相似文献
14.
When a shock wave impinges on a surface, it reflects and propagates across the surface at supersonic velocity. The gas is
impulsively accelerated by the passing shock wave. The resulting high-speed flow imparts sufficiently strong forces to particles
on the surface to overcome strong adhesive forces and entrain the surface-bound particles into the gas. This paper describes
an experimental study of the removal of fine particles from a surface by impinging shock waves. The surfaces examined in this
study were glass slides on which uniformly sized (8.3 μm diameter), spherical polystyrene particles had been deposited. Shock
waves were generated in a small, open-ended shock tube at various heights above and impingement angles to the surface. Particle
detachment from the carefully prepared substrates was determined from images of the surfaces recorded before and after shock
impingement. A single shock wave effectively cleaned a large surface area. The centerline length of the cleared region was
used to characterize the efficacy of shock cleaning. A model based upon the far field solution for a point source surface
shock provides a good fit to the clearance length data and yields an estimate to the threshold shock strength for particle
removal.
Received: 13 November 1997/Accepted: 23 April 1998 相似文献
15.
L. T. Zhang H. H. Shi C. Wang R. L. Dong H. X. Jia X. N. Zhang S. Y. Yue 《Shock Waves》2011,21(3):243-252
In this study, the interaction of a planar shock wave with a group of particles has been investigated using high-speed photography
and dynamic pressure measurements. Experiments were carried out in a horizontal circular shock tube. The influence of the
particle loading ratio, particle diameter, driving gas and shock wave Mach number on the acceleration was studied. It was
found that the higher the particle loading ratio, the greater was the particle velocity. This is due to the higher driving
pressure. Helium and nitrogen gases play quite different roles in acceleration. Pressure multiplication during shock wave
interaction with particles also appears. Based on the experimental results, the discussion regarding partial quantitative
velocities and accelerations of particle groups, as well as the attenuation factors when shock waves pass through the particles,
is given. 相似文献
16.
A. P. Vasil'kov 《Fluid Dynamics》1975,10(5):806-812
The fluid-mechanics equations of a two-velocity, two-temperature medium are used to investigate flow near the stagnation point of a blunt body washed by a hypersonic stream of gas containing solid or liquid deformed particles. The effect of particles of the gasdynamic flow parameters is analyzed. A relaxation layer was found to occur near the body, with marked changes in the gas parameters. It is shown that the presence of particles in the flow reduces the shock stand-off distance. The results of computations on the dynamics and heating of particles in the shock layer are discussed. A solution in finite form is obtained in the limiting case of fine particles by the method of asymptotic expansions. The motion of solid or liquid particles in hypersonic shock layers has been the subject of several papers [1–6], in which particle dynamics was examined, assuming that the particles have a negligible influence on the gasdynamic flow parameters. The solutions obtained are therefore limited to the case of low mass particle concentration in the incident flow. A numerical solution not subject to this limitation was obtained in [7] for supersonic two-phase flow over a wedge. 相似文献
17.
The motion of an inertial dispersed admixture near a plane cylinder immersed in a steady-state hypersonic dusty flow in the
presence of an oblique shock wave interacting with the bow shock is considered. It is assumed that the free-stream particle
mass concentration is small and the particles do not affect the carrier flow. The III and IV shock wave interaction regimes
are considered. The gas flow parameters in the shock layer are calculated from the numerical solution of the full Navier-Stokes
equations for the perfect gas. A TVD second-order finite-difference scheme constructed on the basis of a finite volume method
is used. For calculating the dispersed-phase parameters, including the concentration, the full Lagrangian method is used.
On a wide range of variation of the particle inertia parameters, the patterns of the particle trajectories, velocity, concentration,
and temperature in the shock layer are studied. The possibility of aerodynamic focusing of the particles behind the shock
wave intersection point and the formation of narrow beams with a high particle concentration is revealed. These beams impinge
on the cylinder surface and result in a sharp increase in the local heat fluxes. The maximal possible increase in the heat
fluxes caused by the particles colliding with the cylinder surface is estimated for the flows with and without the incident
oblique shock wave. 相似文献
18.
本文讨论了激波后可燃颗粒点火、燃烧的机制和波后流场的松弛结构,结果表明,点火阶段颗粒外层浓度梯度极大,燃烧速率由非均相化学反应速率决定,而在燃烧阶段,外层的浓度梯度极大,燃烧速率由气体的扩散速率所决定。在考虑管壁效应时,对守恒方程中的能量耗散项作了说明。 相似文献
19.
The acceleration of aluminum particles with a 5μm diameter in the flow field behind an incident shock wave was investigated
experimentally in a 10-m long and 70 mm inner diameter shock tube. By means of instantaneous Laser Doppler Velocimetry (LDV)
the velocity of the particles was observed directly. The light scattered by the moving particles is Doppler shifted and sent
to the laser Doppler velocimeter. The velocimeter essentially consists of a phase-stabilized Michelson interferometer used
as a sensitive spectrometer. An electro-optical circuit ensures the phase stabilization that results in a voltage signal independent
of the scattered light intensity and proportional to the mean velocity of the particles at the measurement point. Because
of the very short response time (1μs) of the LDV system used here, the latter gives a continuous real-time signal of the particle
acceleration. To avoid particle oxidation the particles were accelerated by a high-speed nitrogen gas flow. From the measured
velocity the dimensionless drag coefficient was calculated. The drag coefficient is related to the fluid dynamic force exerted
by the gas on the particles. The experimental data were compared to theoretical models from the literature. A significant
deviation between the model and the experimental data was observed. This deviation is supposed to be induced by the shock
wave, which hits the particles and breaks them into pieces of a smaller diameter. Further experiments will be carried out
in the future to check the size distribution of the particles after the shock has gone past them.
相似文献