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5磁驱动等熵压缩和高速飞片的冲击大电流技术与实验研究进展5.1冲击大电流发生器在一定负载上产生数兆安培以至几百兆安培的冲击大电流,是发展脉冲功率技术的主要目的之一。永久性冲击大电流发生器的主要技术途径是通过电容或电感式中间贮能、与负载匹配的快响应传输线或特殊的 相似文献
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电感储能功率调节系统驱动低电阻负载研究 总被引:1,自引:0,他引:1
对电感储能脉冲功率调节系统驱动低电阻负载的研究进展描述,用电爆炸丝作为断路关头,2uF/100kV电容器作为初级能源,储能电感为1uH。用12Ω硫酸铜水电阻作负载,在负载上可获得350kV、脉宽66ns的脉冲电压,负载电流为32kA,负载峰值功率达12GW。 相似文献
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利用脉冲大电流装置产生随时间变化平滑上升的磁压力,实现对平面、柱面等不同结构样品的磁驱动准等熵(斜波)压缩,为极端条件下材料动力学研究提供了一种偏离Hugoniot状态热力学路径的加载手段。本文从磁驱动准等熵加载装置、实验技术、数据处理方法等方面综述了磁驱动准等熵加载技术研究近十年的新进展,评述了利用磁驱动准等熵加载技术和方法开展极端条件下材料高压状态方程、高压强度与本构关系、相变与相变动力学等方面研究的进展情况,展望了磁驱动准等熵加载技术发展及其在材料动力学、武器物理和高能量密度物理等方面的应用前景。 相似文献
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介绍了Z箍缩(Z-Pinch)辐射源在冲击波物理研究中的应用。Z-Pinch辐射源可在材料中产生几百GPa甚至几千GPa的压力脉冲,扩展了材料状态方程的测量范围。本文着重介绍了Z-Pinch辐射源用于状态方程研究的实验装置结构,诊断方法等。 相似文献
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百万高斯会议是关于强磁场,尤其是以炸药为能源的爆炸磁压缩装置和爆炸电流发生器的系列性专业国际学术会议本次会议于86年7月14日至17日在美国新墨西哥州圣塔菲市召开,共有十一个国家243人参加,交流论文近110篇,大多数来自美国和苏联。我国有三人与会,宣读了西南流体物理研究所关于小型爆炸电流发生器的研究论文。会后组织参观了美国洛斯阿拉莫斯(LANL)圣地亚(SNL)及空军武器实验室(AFWL)等单位。 相似文献
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A numerical approach is proposed to simulate the interaction between flow and flexible nets in steady current. The numerical approach is based on the joint use of the porous-media model and the lumped-mass model. The configuration of flexible nets can be simulated using the lumped-mass model and the flow field around fishing nets can be simulated using the porous-media model. Using an appropriate iterative scheme, the fluid–structure interaction problem can be solved and the steady flow field around flexible nets can be obtained. In order to validate the numerical models, the numerical results were compared with the data obtained from corresponding physical model tests. The comparisons show that the numerical results are in good agreement with the experimental data. Using the proposed numerical approach, this paper presents the flow field around a single flexible net and two flexible nets with a spacing distance. Both the configuration of the flexible nets and the flow velocity results are in accordance with those of the corresponding physical model tests. 相似文献
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基于考察泥沙运动的细观行为特征,采用离散单元法(DEM)模拟泥沙颗粒运动,结合带自由表面的水动力学计算模型,建立了CFD-DEM耦合数值模型。计算程序开发基于Fortran语言来实现。耦合模型中实现了硬球模型和软球模型两种颗粒碰撞模型,应用范围较广。作为自由表面水流与泥沙颗粒流数值模型的初步研究,在模型建立的基础上,对模型做了基本的验证。分别通过单颗粒静水沉降和混合颗粒群分选两个计算工况,验证了模型的正确性及模拟精度。该耦合模型可进一步丰富带自由表面水流条件下泥沙运动的研究手段。 相似文献
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The shock stand-off distance of a spherical model flying with transonic speeds is determined through numerical simulations.
The model decelerates due to drag forces caused by the pressure and viscous shear stress at the model surface. Two-dimensional
axisymmetric numerical codes with numerical grids fixed to the flying spherical model are used in the simulations. Numerically
determined shock stand-off distances are compared with experimental data obtained in a previous study as well as with those
obtained in our ballistic-range experiments. The numerical results and the experimental data are found to be in good agreement.
In addition, the time-dependent shock stand-off distance of a decelerating model is investigated. 相似文献
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A numerical model of pollutant transport acted by water waves on a shallow‐water mild‐slope beach is established in this study. The numerical model is combined with a wave propagation model, a multiple wave‐breaking model, a wave‐induced current model and a pollutant convection–dispersion model. The wave propagation model is based on the higher‐order approximation of parabolic mild‐slope equation which can be used to simulate the wave refraction, diffraction and breaking in a large area of near‐shore zone combined with the wave‐breaking model. The wave‐induced current model is established using the concept of the radiation stress and considering the effect of bottom resistance caused by waves. The numerical model is verified by laboratory experiment results of regular and irregular waves over two mild beaches with different slopes. The numerical results agree well with experimental results. The numerical model has been applied in the near‐shore zone of Bohai bay in China. It is concluded that pollutant transport parallel to the shoreline due to the action of waves, which will induce serious pollution on the beach. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
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A 2D numerical model is proposed to simulate unsteady cavitating flows. The Reynolds‐averaged Navier–Stokes equations are solved for the mixture of liquid and vapour, which is considered as a single fluid with variable density. The vapourization and condensation processes are controlled by a barotropic state law that relates the fluid density to the pressure variations. The numerical resolution is a pressure‐correction method derived from the SIMPLE algorithm, with a finite volume discretization. The standard scheme is slightly modified to take into account the cavitation phenomenon. That numerical model is used to calculate unsteady cavitating flows in two Venturi type sections. The choice of the turbulence model is discussed, and the standard RNG k–εmodel is found to lead to non‐physical stable cavities. A modified k–εmodel is proposed to improve the simulation. The influence of numerical and physical parameters is presented, and the numerical results are compared to previous experimental observations and measurements. The proposed model seems to describe the unsteady cavitation behaviour in 2D geometries well. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
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基于CT扫描的花岗岩三维数值试件重构模型及应用 总被引:2,自引:0,他引:2
岩石细观结构控制宏观破裂模式,建立一种表征岩石细观结构的数值模型重构方法并能够嵌入到力学模型中计算岩石破坏过程应力分布,对于揭示岩石破坏机理具有重要的理论意义.论文以花岗岩试件为研究对象,借助于先进的CT技术获取试件内部结构切片图像,利用数字图像处理技术实现了基于CT图像的花岗岩试件结构的识别和表征,基于矢量化方法和岩石破裂过程分析系统RFPA3D建立了花岗岩三维数值试件,对花岗岩试件单轴压缩破裂过程进行了数值模拟.通过数值试验结果与物理实验结果对比发现,基于CT扫描的花岗岩数值试件真实表征了岩石细观结构,所以力学模拟得到的破裂模式与室内物理实验得到的破裂模式相似,同时能够解译岩石破裂力学机理,为深入研究岩石、复合材料等力学特征提供了一种可行方法. 相似文献
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Xu Zhang William D. Armstrong William R. Lindberg Jonathan W. Naughton 《Experiments in fluids》2012,53(4):1107-1121
Experimental measurements are used to validate a numerical model of a dynamic resonant wall shear stress sensor. The numerical model consists of an unsteady two-dimensional boundary-layer model for the flow and a simple mechanical model for the sensor itself. The sensor’s sensitivity to wall shear stress is experimentally determined in a flat-plate boundary layer, and the results agree closely with those from the numerical simulations. Using the validated model, it is determined that the energy lost in each sensor oscillation due to the interaction between the sensor and fluid increases with increasing mean wall shear stress. 相似文献
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We assess the applicability of the numerical dissipation as an implicit turbulence model. The nonoscillatory finite volume numerical scheme MPDATA developed for simulations of geophysical flows is employed as an example of a scheme with an implicit turbulence model. A series of low resolution simulations of decaying homogeneous turbulence with and without Coriolis forces in the limit of zero molecular viscosity are performed. To assess the implicit model the long-time evolution of turbulence in the simulations is investigated and the numerical velocity fields are analyzed to determine the effective spectral eddy viscosity that is attributed to the numerical discretization. The detailed qualitative and quantitative comparisons are made between the numerical eddy viscosity and the theoretical results as well as the intrinsic eddy viscosity computed exactly from the velocity fields by introducing an artificial wave number cutoff. We find that the numerical dissipation depends on the time step and exhibits contradictory dependence on rotation: it is overestimated for rapid rotation cases and is underestimated for nonrotating cases. These results indicate that the numerical dissipation may fail to represent the effects of the physical subgrid scale processes unless the parameters of a numerical scheme are carefully chosen. 相似文献