高超声速飞行器强激波后高温气体会形成具有导电性的等离子体流场， 电离气体为磁场应用提供了直接工作环境。 磁流体流动控制技术利用外加磁场影响激波后的离子或电子运动规律， 可以有效改善高超声速飞行器气动特性； 该技术具有非接触、 主动控制、 无复杂机械部件、 响应时间短等优势， 具有广阔应用前景。弓形激波作为高超声速磁流体流动控制较为直观的气动现象， 受到研究者重点关注， 磁场添加后弓形激波结构发生变化， 进而可以直接反映磁控效果。 当前， 关于磁控弓形激波的研究依旧非常有限， 包括磁控激波脱体距离理论研究、 磁控弓形激波建立过程等。 此外， 国内尚未开展该领域的实验研究工作。 本文采用理论分析与数值计算方法研究了高温气体效应影响下磁控弓形激波的建立过程， 并在高焓脉冲设备中进行初步的实验观测， 主要研究内容如下：
1. 基于偶极子磁场分布和低磁雷诺数假设条件， 通过将连续方程积分， 利用动量方程建立流场与磁场的联系， 采用分离变量及量级分析方法， 对激波层内驻点线附近区域进行求解， 得到了磁控激波脱体距离关于磁相互作用系数以及激波前后密度比的解析关系， 该理论模型可以达到快速评估磁控效果的目的。
2. 在理想气体模型条件下， 将 Patz 理论与数值计算相结合， 研究磁场对弓形激波建立过程的影响。 另外， 考虑高温真实气体效应， 采用空气 7 组分化学反应模型， 对弓形激波建立过程数值模拟， 从反射激波位移和驻点压力的时间历程分析高温电离作用对磁控弓形激波建立过程的影响， 进而获得磁场添加对弓形激波达到稳定状态所需时间的影响规律， 并分析了流场稳定延迟对在脉冲实验装置中的磁流体流动控制实验所带来的影响。
3. 利用高温气体动力学国家重点实验室的激波管/风洞（JF10 风洞、 JFX 风洞以及Φ800 激波管） ， 对高超声速磁流体流动控制进行初步实验研究， 观测了磁控弓形激波建立过程以及稳定状态。 采用球形钕磁体作为磁场源装置， 气动外壳为球头； 观测方法采用纹影法和直接拍摄自发光法。 在实验过程中尝试空气和氩气两种实验气流， 通过对比有无磁场的球头激波脱体距离， 观察和分析磁控效果。

High speed and shock compression behind the bow shock of an aircraft head result in very high temperature, which would subsequently lead to a conductive plasma flow field around the hypersonic vehicle. The plasma gas provides a direct working environment for magnetic field. The magnetohydrodynamic (MHD) flow control, which manipulates the magnetic field to alter the trajectory of ions or electrons, can improve the aerodynamic characteristics of hypersonic vehicles effectively. It has a number of advantages, such as the non-intrusive, active control, no complex mechanical parts and short response time, and has broad application prospects. As an intuitive aerodynamic phenomenon in the field of hypersonic MHD flow control, bow shock waves have attracted close attention from researchers. Under the influence of the applied magnetic field, the structure of bow shock waves will change with it, which can directly reflect the effect of MHD flow control. However, the current research on the MHD bow shock waves is still very limited, including the theoretical research on the MHD shock stand-off distance, the establishment process of the MHD bow shock waves, etc. In addition, experimental research in this field has not been carried out in China. In this paper, the formation of MHD bow shock waves under the influence of high-temperature gas effects has been studied with theoretical analysis and numerical simulation, and preliminary experimental observations have been performed in the high enthalpy pulse facilities. The main work of present thesis include:
1. By means of radially integrating the continuity equation and applying mathematical method of variable separation to the momentum equation, the theoretical analysis for MHD shock stand-off distance has been performed. The analysis was based on the assumption of low magnetic Reynolds number and the common-used dipole distribution of magnetic field as applied. The relationship between the shock stand-off distance and the variables of the magnetic interaction parameter and the density ratio has been obtained.
2. Ideal gas model was firstly applied. Patz’s theory and numerical calculation are combined to study the basic influence of magnetic field on the establishment process of bow shock waves. Further, the effect of high temperature gases has been considered. The chemical reaction model with 7 species of ionized air has been adopted. The time histories of reflected shock wave displacement and the stagnation pressure have been analyzed to describe influence from high temperature ionization on MHD flow control, through which the delay effect caused by magnetic field has been studied. The influence caused by delayed stabilization of flow field on MHD experiments in the pulse equipments has been analyzed.
3. The preliminary experimental study of hypersonic MHD flow control has been carried out by using the shock tube/shock tunnels of State Key Laboratory of High Temperature Gas Dynamics (LHD), and the establishment process and steady state of MHD bow shock waves were observed. A spherical neodymium magnet was used as the magnetic field device, and a spherical head was applied as areodynamic shell. Schlieren method and directly shooting gas luminosity method were used for observation. During the experiments, test gases of air and argon were applied. The MHD effect was observed and analyzed by comparing the stand-off distance of the bow shock waves with or without magnetic field.