Study of Nonequilibrium High-Speed Plasma Flows with a Large Amount of Oxygen Atom

(1)研制了适用于空气、氮气或氧气的非平衡等离子体发生器进行试验。等离子炬的阳极为Cu，阴极为Hf。Hf阴极对减少电极的损伤是有效的。初步实验表明，等离子体流的核心长度约为2-6 cm，其温度范围为4000-9000K，随实验室压力的变化而变化。结果表明，该装置可用于研究物质与非平衡等离子体的相互作用。(2)对强空气激波在激波管内的传播过程进行了数值研究，包括了详细的非平衡反应过程和辐射过程。计算了M=20以上激波马赫数时的气体动力学行为。在M bbb30处，发现了独特的辐射特性，在辐射强度分布上有两个峰，一个是由于非平衡物理化学过程，另一个是由于平衡物理化学过程。(3)用数值方法研究了非平衡化学反应速率、振动松弛截面等物理参数对强氮激波中低密度滞流的影响。这些参数对激波层内的流动特性有较大的影响，但对到达驻点的对流换热率影响很小。(4)基于“有效键能”概念，计算了O_2、N_2、NO和C_2的非平衡离解反应速率和有效离解能。给出了有效离解能的简单数学表达式。(5)采用莫尔纹影法对超声速自由射流进行了结构可视化研究。利用作者提出的数学变换方法，对三维喷管的射流结构进行了澄清。(6)利用maecker等离子体发生器对空气等离子体的非平衡辐射进行了初步研究。结果表明，等离子体温度约为6000 ~ 10000k，相对低温区以N_2分子带为主，高温区以N、O相关辐射为主。少

(1) Nonequilibrium plasma generator which operates for air, nitrogen or oxygen gas was made for trial. Plasma torch has Cu anode and Hf cathode. The Hf cathode was effective for reducing the damage of the electrode. Preliminary experiments indicate that the core of plasma flows is about 2-6 cm long, and its temperature ranges 4000-9000K, depending on test-chamber pressure. From the results, it was found that the present apparatus was useful for the study of an interaction of material with nonequilibrium plasmas.(2) Strong air shock waves propagating in a shock tube were investigated numerically, detailed nonequilibrium reactive and radiative processes being included. Gas dynamic behaviors were calculated for shock Mach number above M=20. At M>30, unique radiative property with two peaks in radiative intensity distribution was found, one of which was due to nonequilibrium physico-chemical process and the other due to equilibrium one.(3) Low-density stagnation-flows in a strong N_2 shock … More layer were studied numerically to examine the effect of physical parameters such as nonequilibrium chemical reaction rates, cross section for vibrational relaxation, and so on. These parameters were found to have large effect on flow properties in the shock layer, but have very minor effect on the convective heat transfer rate to a stagnation point.(4) Nonequilibrium dissociation reaction rates and effective dissociation energy for O_2, N_2, NO and C_2 were calculated based upon the concept of "effective bond energy". Simple mathematical expressions for the effective dissociation energy are presented.(5) The Moire-Schlieren method was applied to supersonic free jets to visualize and investigate their structure. Using mathematical transformation method developed by the authors, jet structures from 3D nozzles were clarified.(6) Nonequilibrium radiation from air plasma was preliminarily investigated by means of the Maecker-type plasma generator. It was found that the plasma temperature was about 6000-10000K, and that N_2 molecular bands predominated for relatively low-temperature region and radiations associated with N and O did for high-temperature zone. Less