【作者】 杨波；

【导师】 倪晓武；

【作者基本信息】 南京理工大学 ， 光学工程， 2007， 博士

【摘要】 本文从理论和数值模拟方面对激光推进中冲击波在固体中传播和衰减特性、激光支持爆轰波的冲量耦合过程及其随环境气压变化对应的不同作用机理进行了研究。在对激光等离子体冲击波在固体中传播和衰减的研究中，根据点爆炸的球对称模型，引入了极坐标下等熵非定常流动的球面波质量、动量守恒方程，得到了LSD波(激光支持爆轰波)对固态靶表面的作用压力；就稀疏波追赶冲击波模型提出了压力的梯形模型，得到了冲击波产生的压力随传播距离变化关系，且理论分析和数值模拟结果与实验结果吻合。利用悬摆法和光电测速相结合的方法，研制了激光靶冲量耦合测试系统，建立了基于小雷诺数绕流空气阻力模型的靶摆运动方程，得到了激光作用于靶的初始冲量。综合激光靶冲量耦合实验和流体动力学数值模拟的结果，得到了激光吸收区的组分，根据其中等离子体的变化结果可以得到标准大气压下LSD波的点燃阈值。在利用真空箱模拟真空环境的基础上，得到了冲量耦合系数随环境气压的变化情况，进而发现当环境气体的气压变大时LSD波点燃机制的转变。通过对激光吸收区的成分和稀疏波与LSD波相互作用过程的分析，得到了表征等离子体微观过程的位力系数。本文的研究结果对激光推进技术和金属表面激光热处理等激光加工技术的研究均有参考价值。更多还原

【Abstract】 The shock propagation and attenuation in solid in the process of laser propulsionand the impulse coupling process of Laser-Supported Detonation Wave with differentambient pressure are studied in this paper by analyzing the data simulation andtheoretical result.In the study of the shock propagation and attenuation in solid, according toconstraint conditions of the point-explosion spherical shock transmission, by adoptingthe polar coordinate for describing the isentropic mass and momentum conservationequation of spherical wave, the pressure on the solid target applied by theLaser-Supported Detonation Wave is determined. Based on the theoretical model ofrarefaction wave overtaking shock, the equicrural trapezoidal pressure profile isdeduced for the relation between shock pressure and time interval. The relationbetween shock pressure and propagation distance can be determined and iscorrespondence with the data simulation and experimental result.By the self-developed test system of laser impulse coupling to target based on thependulous method and the light electric tachometry, the experimental result is scaled.The pendulous equation of resistance model of low Reynolds number is founded andadopted for the initial impulse of laser coupling to target and examined by theexperimental method. Considering the experimental and hydrodynamic resultsgenerally, the components in the laser absorption zone can be determined byanalyzing the mechanical effect of Laser Supported Detonation Wave of interactionbetween laser and ambient gas or evaporation applied to the target. The ignitionthreshold of Laser Supported Detonation Wave can be determined by analyzing theplasma component in laser absorption zone under the standard atmosphere. Using thevacuum chamber for simulating the vacuum environment based on upward theoreticalprinciple, the relation between impulse coupling coefficient and ambient pressure. Byanalyzing the relation between experiment and numerical simulation, with theincrement of ambient pressure, the components in the laser absorption zone are fromplasma and target evaporation to plasma and ambient air. The phenomenon indicatesthe ignition mechanical transition of Laser Supported Detonation Wave, that is, LaserSupported Detonation Wave is ignited from target evaporation to ambient air. The experimental results can be divided into three stages based on components in the laserabsorption zone and the interaction between Laser Supported Detonation Wave andthe rarefaction wave, and the virial coefficient which indicates the micro phenomenonof plasma can be determined.These research results will provide the theoretical, numerical simulationreferences for laser processing technology, such as laser propulsion and heat treatmentof metal surface.更多还原