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101.
利用量级分析和风洞实验研究了可压缩混合层流动第二发展阶段气动光学效应的规律性.理论分析主要针对二维大尺度结构存在时视线误差(boresight error,BSE)与混合层流场及其特征参数之间的关系进行了讨论.研究结果表明:在混合层发展的第二阶段,时均BSE与对流马赫数呈现出复杂的非线性关系;同时还发现流场中的湍动能和混合层界面处的雷诺应力分布也是影响时均BSE的重要因素;采用细光束穿越混合层流场的风洞试验结果主要证实了时均BSE与对流马赫数之间的非线性关系. 相似文献
102.
103.
Study of electron drift velocity caused by Etimes B motion is done with the help of a Mach probe in a dc cylindrical magnetron sputtering system at different plasma discharge parameters like discharge voltage, gas pressure and applied magnetic field strength. The interplay of the electron drift with the different discharge parameters has been investigated. Strong radial variation of the electron drift velocity is observed and is found to be maximum near the cathode and it decreases slowly with the increase of radial distance from the cathode. The sheath electric field, E measured experimentally from potential profile curve using an emissive probe is contributed to the observed radial variation of the electron drift velocity. The measured values of the drift velocities are also compared with the values from the conventional theory using the experimental values of electric and magnetic fields. This study of the drift velocity variation is helpful in providing a useful insight for determining the discharge conditions and parameters for sputter deposition of thin film. 相似文献
104.
105.
The lattice‐BGK method has been extended by introducing additional, free parameters in the original formulation of the lattice‐BGK methods. The relationship between these parameters and the macroscopic moment equations is analysed by Taylor series and Chapman–Enskog expansion. The parameters are determined from the macroscopic moment equations by comparisons with the governing equations to be modelled. Extensions are presented for the Navier–Stokes equations at low Mach numbers in Cartesian or axisymmetric coordinates with constant or variable density, for scalar convection–diffusion equations and for equations of Poisson type. The generalized lattice‐BGK concept is demonstrated by two applications of chemical engineering. These are the computation of chemically reacting flow through an axisymmetric reactor and of the transport and deposition of particles to filters under the action of different forces. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
106.
1 Introduction TheconventionalMach Zehnderinterferometerisanimportantdiagnostictool.Frequentlyusedinthefieldsofplasmaphysics,aerodynamics,andheattransferformeasuringdensity ,pressure ,andtemperaturechangesingases.Becauseofitsrelativelylargeandfreelyacces… 相似文献
107.
改进了有限差分格子Boltzmann方法(FDLBM),以直接数值模拟气动噪声.基于LB求解器特性,采用动力学方程中的恒定对流速度以实施高阶迎风差分,提高了声波和湍流的分辨率.通过建立一个新的三维粒子模型,计算得到了任意比热容的三维可压缩Navier-Stokes系统.此外,利用Bhatnagar-Gross-Krook (BGK)碰撞算子,通过引入热流量修正,实现了Prandtl数的可变性.在激波管内弱声波以及伴随有温度梯度的Taylor-Couette层流的验证计算中,提出的新方法结果良好.此外也对NACA0012翼型绕流进行了三维模拟.其中,Reynolds数、Mach数和攻角分别取2× 105,8.75×10-2以及9°.计算发现,在机翼前缘附近的分离气流位置,以及表面压力波动强度的Maeh数依赖性方面,数值计算结果与实验结果相吻合. 相似文献
108.
The substantial drop of the plasma temperature along magnetic field lines with increasing plasma density is one of the main features in tokamak divertors. As a result the temperature gradient at the divertor plates becomes very steep and the boundary condition normally applied for the parallel Mach number M at the target, Mt = 1, cannot be satisfied. In this case the value of Mt based on the general form of the Bohm criterion, Mt 1, has to be determined from the continuity of plasma parameters.In the present paper a new approach to resolve the Mach number at the target for such a situation is proposed. This method avoids the singularity problem that arises by treating the particle balance and parallel motion equations in a differential form. Instead, the integral representation of the equations is formulated for an arbitrary form of particle and momentum sources. The approach can also take into account transport perpendicular to the magnetic field lines.The proposed method is demonstrated on the example of a one-dimensional stationary model for the scrape-off layer (SOL) plasma and includes the continuity-, parallel momentum- and heat transfer equations. The recycled neutrals are described in the diffusion approximation. In the case of low density the normal condition Mt = 1 is satisfied and the results are in agreement with the two-point model. At high enough plasma density solutions with the supersonic flow at the divertor plates, Mt > 1, are found. These states correspond to a partially detached plasma with a temperature of a few eV. 相似文献
109.
A normalized plasma flow velocity in highly collisional plasma formed by a microwave plasma jet, which is dimensionless unit for plasma flow velocity/ion acoustic velocity, was measured by the parallel Mach probe. To deduce the normalized plasma flow velocity under highly collisional plasma conditions, the collisional model of a Mach probe was proposed. In addition, neutral gas flow velocity which assumed to be plasma flow velocity was calculated by the turbulent model. The results for the two different models were compared with those for the collsionless models of the Mach probe. The turbulent model produced 2–4 times reduced values than by measurements with collsionless models. The measured results with the collisional model were shown as approximately 100–250% lower than those for collsionless models. They were obtained to be in good agreement with difference rate of 10–30% when compared to those for the turbulent model. 相似文献
110.
This paper is concerned with the low Mach number limit for the compressible Navier-Stokes equations in an exterior domain.We present here an approach based on Strichartz estimate defined on a non trapping exterior domain and we will be able to show the compactness and strong convergence of the velocity vector field. 相似文献