共查询到19条相似文献,搜索用时 187 毫秒
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采用低磁雷诺数磁流体数学模型,对外加磁场下的高超声速半球体流场进行数值模拟.选取三种简单理想磁场(轴向、径向、周向均布磁场),分析了不同磁场类型对流场结构、气动阻力与洛伦兹阻力的影响及作用机理.研究发现,轴向磁场径向"挤压"效应使得激波外形凸出,且壁面静压存在"饱和现象";径向磁场存在轴向"外推"效应,较大的磁场强度会导致肩部形成高温区;周向磁场下感应电场的存在导致增阻效果很差.进而对比了两种相同驻点磁感应强度特殊分布磁场(偶极子磁场、螺线管磁场)下的流场,发现了不同于理想磁场的径向"扩张"效应.按增阻效果从大到小依次为径向磁场、螺线管磁场、轴向磁场、偶极子磁场、周向磁场. 相似文献
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对液态金属自由表面膜流在强磁场下的磁流体力学效应进行了数值模拟研究,获得了液态金属自由表面的形状、截面流速分布及截面上的电动势分布,从而能对膜流的一些磁流体动力学行为作出解释。数值计算结果与理论分析和实验结果符合较好。由实验和数值模拟结果可以得出,液态金属膜流通过强磁场时,磁场会阻碍膜流的运动。 相似文献
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为了提高微波等离子推力器性能,改善等离子体对电磁波能量的吸收状况,提高核心区温度,提出外加磁场的方案,并对热等离子体进行了数值模拟.假设局域热平衡条件,采用Navier-Stokes,Maxwell和Saha方程,利用压力修正的半隐格式和时域有限差分求解方法,建立了径向磁镜场下推力器内等离子体流场的数值计算模型.数值模拟结果表明:外加磁场后的磁感应强度小于0.5 T时,推力器内热等离子体核心区最高温度随磁感应强度的增加而迅速提高.外加磁场后的磁感应强度大于0.5 T时,核心区最高温度随磁感应强度的增加而缓慢提高.磁感应强度为0.5 T时,热等离子体核心区最高温度与不加磁场相比提高了24%.外加磁场对等离子体流场速度分布影响不大.
关键词:
等离子体模拟
等离子体相互作用
等离子体流动 相似文献
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针对等离子体流场的模拟准确性问题及其对高超声速磁流体控制的影响,通过数值求解三维非平衡Navier-Stokes流场控制方程和Maxwell电磁场控制方程,建立了三维低磁雷诺数磁流体数值模拟方法及程序,分析了不同空气组分化学反应模型和壁面有限催化效率等因素对高超声速磁流体控制的影响.研究表明:不同空气组分化学反应模型对高超声速磁流体流场结构、气动力/热特性控制的影响不容忽视;对于本文计算条件,Park化学反应模型在组分模型一致性、等离子体模拟准确性等方面具有一定优势;磁控热防护效果,受壁面有限催化复合系数影响较大,两者呈非线性关系,不同表面区域差异较大;磁场对磁阻力伞及其磁阻力特性影响,受壁面催化效应的影响相对较小. 相似文献
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《物理与工程》2016,(1)
基于特殊性能的磁性液体增设了综合性设计性实验项目,根据项目式教学法初步实现了以学生自我训练为主的教学模式.本文设计了磁性液体磁表面张力系数智能测试仪,研究了均匀磁场中4种不同类型磁性液体的磁表面张力系数随磁感应强度的变化规律.随外加磁场磁感应强度的增强,磁性液体的磁表面张力系数增大,主要是磁场增强了磁性颗粒之间的相互作用力.磁感应强度相同时,载液质量对磁性液体的磁表面张力系数影响较大,载液质量越小,单位体积内融入的磁性颗粒数量越多,导致磁性液体的磁表面张力系数越大.表面活性剂种类对磁性液体磁表面张力系数的影响也较大,由于油酸对磁性颗粒的吸附作用比PBSI-941表面活性剂强,油酸官能团较早吸附在磁性颗粒表面,限制了磁性颗粒进一步长大,导致MFO-4磁性液体磁表面张力系数较小. 相似文献
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本文提出一种采用石榴石型铁氧体磁性材料的太赫兹滤波器,利用波导线缺陷和腔内点缺陷的耦合特性,通过改变腔内介质柱半径及分布,实现对某个波长的耦合,达到了高效率滤波的功能;改变外磁场的大小,影响铁氧体材料的磁导率变化,使谐振频率发生改变,从而对THz波进行滤波.应用平面波展开法(PWM)和时域差分有限法(FDTD)进行仿真分析,研究结果表明,该滤波器其插入损耗为0.0997 d B,3 d B带宽为8.22 GHz,实现了低损耗窄带滤波. 相似文献
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This paper presents a numerical investigation of the hydro-thermal behavior of a ferrofluid (sea water and 4 vol% Fe3O4) in a rectangular vertical duct in the presence of different magnetic fields, using two-phase mixture model and control volume technique. Considering the electrical conductivity of the ferrofluid, in addition to the ferrohydrodynamics principles, the magnetohydrodynamics principles have also been taken into account. Three cases for magnetic field have been considered to study mixed convection of the ferrofluid: non-uniform axial field (negative and positive gradient), uniform transverse field and another case when both fields are applied simultaneously. The results indicate that negative gradient axial field and uniform transverse field act similarly and enhance both the Nusselt number and the friction factor, while positive gradient axial field decreases them. It is also concluded that, under the influence of both fields by increasing the intensity of uniform transverse field the effect of non-uniform axial fields decrease. 相似文献
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采用基于OpenFOAM环境自主开发的低磁雷诺数磁流体求解器,对45°和90°突扩矩形管中液态金属流体在受到垂直流向的外加磁场作用时的速度、感应电流、压力的分布及突扩位置处的MHD三维现象进行数值模拟.结果表明:磁场沿突扩方向时,由于无回流涡,45°比90°突扩管在肩部位置速度分布更优.哈特曼数增大,强射流和突扩结构,在突扩肩部位置引发流动的不稳定性.伴随感应电流的不稳定,流动不稳定发展到突扩位置上游.磁场沿垂直突扩方向时感应电流的三维效应显著.哈特曼数增大,MHD压降显著增大.同方向磁场和相同哈特曼数,不同突扩角度的三维无量纲压力梯度无明显差异. 相似文献
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Manuk G. Barseghyan Albert A. Kirakosyan 《Physica E: Low-dimensional Systems and Nanostructures》2005,28(4):471-481
The quantum states and energy spectrum of an electron in a rectangular step quantum well in a magnetic field parallel to the plane of two-dimensional electronic gas are investigated. It is shown that the joint effect of a magnetic field and confining potential of quantum well results in radical change of the electron energy spectrum. The energy dependencies on the parameters of the quantum well and magnetic field induction are investigated. Numerical calculations are carried out for an AlAs/ GaAlAs/ GaAs/ AlAs step quantum well. 相似文献
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A theory has been constructed that strictly describes the spectrum of dipole-exchange spin waves in an arbitrarily magnetized anisotropic ferrite waveguide with a rectangular cross section. The theory takes into account the spatial inhomogeneity of the internal magnetic field in the waveguide cross section. The influence of parameters of the ferrite waveguide on the distribution of the internal magnetic field in the waveguide cross section is analyzed. The dispersion characteristics of two waveguide types most widely used in practice are investigated. The dipole-exchange spin wave spectra calculated for a transversely magnetized waveguide are presented and the distributions of the dynamic magnetization in the waveguide cross section for several types of volume and localized spin-wave modes are constructed. 相似文献
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The pair distribution function of a monodisperse magnetic fluid simulated by a liquid made of dipolar hard spheres with constant
magnetic moments is calculated. The anisotropy of the pair distribution function and the related structure factor of scattering
in a dc uniform magnetic field are studied. The calculation is performed by diagrammatic expansion in the volume concentration
of particles and the interparticle magnetic-dipole interaction intensity using a thermodynamic perturbation theory. Limitation
by three-particle diagrams makes it possible to apply the results obtained to magnetic fluids with a moderate concentration.
Even for low-concentration and weakly nonideal magnetic fluids, the anisotropic interparticle magnetic-dipole correlations
in a magnetic field lead to the repulsion of particles in the direction normal to the field and to the formation of particle
dimers along the field. 相似文献
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The effect of magnetic field on electron energy spectrum, wave functions and probabilities of intraband quantum transitions in multilayered spherical quantum-dot-quantum-well (QDQW) CdSe/ZnS/CdSe/ZnS is studied. Computations are performed in the framework of the effective mass approximation and rectangular potential barriers model. The wave functions are expanded over the complete basis of functions obtained as exact solutions of the Schrodinger equation for the electron in QDQW without the magnetic field.It is shown that magnetic field takes off the spectrum degeneration with respect to the magnetic quantum number and changes the localization of electron in the nanostructure. The field stronger effects on the spherically-symmetric states, especially in the case of electron location in the outer potential well. The magnetic field changes more the radial distribution of probability of electron location in QDQW than the angular one. The oscillator strengths of intraband quantum transitions are calculated as functions of the magnetic field induction and their selection rules are established. 相似文献
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Modified magnetomechancial model in the constant and low intensity magnetic field based on J-A theory 下载免费PDF全文
《中国物理 B》2017,(7)
The existing magnetomechancial models cannot explain the different experimental phenomena when the ferromagnetic specimen is respectively subjected to tension and compression stress in the constant and low intensity magnetic field,especially in the compression case. To promote the development of magnetomechancial theory, the energy conservation equation, effective magnetic field equation, and anhysteretic magnetization equation of the original Jiles-Atherton(J-A)theory are elucidated and modified, an equation of the local equilibrium status is employed and the differential expression of the modified magnetomechancial model based on the modified J-A theory is established finally. The effect of stress and plastic deformation on the magnetic parameters is analyzed. An excellent agreement is achieved between the theoretic predictions by the present modified model and the previous experimental results. Comparing with the calculation results given by the existing models and experimental results, it is seen indeed that the modified magnetomechanical model can describe the different magnetization features during tension-release and compression-release processes much better, and is the only one which can accurately reflect the experimental observation that the magnetic induction intensity reverses to negative value with the increase of the compressive stress and applied field. 相似文献