非定常等离子体射流数值研究

发布时间：2018-01-30 07:17

本文关键词： 等离子体非定常射流外加磁场偏转特性　出处：《南京理工大学》2017年硕士论文　论文类型：学位论文

【摘要】：为探究等离子体射流在大气中的流动规律,诸多学者开展了较为广泛的理论、实验和数值计算研究。由于受到实验周期、实验环境以及经济因素等诸多条件的限制,人们常采用数值模拟的方法开展对这一领域的研究。随着计算流体力学的发展,采用数值模拟计算对等离子体射流的发展过程进行研究也逐渐成为经济、有效的手段。新概念武器,如电磁轨道炮、电热化学炮在发射后,喷出非定常高速等离子体射流,会对周围环境或者设备等构成危害,如电磁辐射、高温烧蚀等。因而,从发射安全的角度讲,开展非定常等离子体射流的研究,具有非常重要的现实意义。本文对非定常等离子体射流在有、无外加磁场,以及不同初始条件下,如速度和压力分布,对等离子体射流流场结构及其发展过程进行了数值模拟,讨论了等离子体射流流场的发展特征和偏转特性。并采用高精度计算格式对其进行了数值模拟,对比了不同计算格式下非定常射流的流场结构。数值模拟时,二维部分的基本方程为不考虑粘性的欧拉方程,计算采用Roe格式和WENO格式;三维部分的基本方程为Navier-Stokes方程,并求解MHD方程,计算采用AUSM格式。二维非定常射流的计算部分分别采用了二阶Roe格式,五阶、七阶WENO格式计算了激波管黎曼问题,并选用五阶WENO格式计算等离子体欠膨胀射流,与AUSM格式的计算结果进行对照表明,WENO格式的耗散性较小,可以更清晰的表现欠膨胀射流的结构特点。三维非定常射流部分,主要对磁场强度以及不同初始条件下等离子体射流的偏转特性进行了数值模拟,数值结果表明等离子体射流在外加磁场的作用下发生了偏转,其偏转角度随外加磁场强度的增大而增大,近似呈线性变化;不同初始速度和压力也会影响等离子体射流的偏转,偏转角度随着速度和压力的增大而增大。
[Abstract]:In order to investigate the flow law of plasma jet in the atmosphere, many scholars have carried out a wide range of theoretical, experimental and numerical research. With the development of computational fluid mechanics (CFD), many conditions such as experimental environment and economic factors are limited, people often use numerical simulation method to carry out the research in this field. Numerical simulation is used to study the development process of plasma jet. The new concept weapon, such as electromagnetic rail gun, electrothermal chemical gun, has become an economic and effective means. The ejection of unsteady high speed plasma jet will cause harm to the surrounding environment or equipment, such as electromagnetic radiation, high temperature ablation, etc. Therefore, the research of unsteady plasma jet is carried out from the point of view of launch safety. This paper deals with the distribution of velocity and pressure in unsteady plasma jet with or without external magnetic field and under different initial conditions. The structure and development process of plasma jet flow field are numerically simulated. The development and deflection characteristics of plasma jet flow field are discussed. The flow field structure of unsteady jet under different computational schemes is compared. In numerical simulation, the basic equation of two-dimensional part is Euler equation without viscosity, and the Roe scheme and WENO scheme are used in the calculation. The basic equation of the three-dimensional part is the Navier-Stokes equation, and the MHD equation is solved. The second order Roe scheme, the fifth order scheme and the seventh order WENO scheme are used to calculate the Riemannian problem of shock tube. The fifth order WENO scheme is used to calculate the plasma underexpansion jet. The comparison with the results of AUSM scheme shows that the dissipative property of Weno scheme is small. Three dimensional unsteady jet, the magnetic field intensity and the plasma jet deflection characteristics under different initial conditions were numerically simulated. The numerical results show that the plasma jet deflects under the action of the external magnetic field, and the deflection angle increases with the increase of the external magnetic field intensity, which is approximately linearly changed. Different initial velocities and pressures also affect the deflection of the plasma jet, and the deflection angle increases with the increase of velocity and pressure.
【学位授予单位】：南京理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O358;TJ01

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