【作者】 冮强；

【导师】 范宝春；

【作者基本信息】 南京理工大学 ， 热能工程， 2004， 硕士

【摘要】 本文属于工程力学研究领域，课题源于自然科学基金《收敛激波与火焰作用对燃烧转爆轰的强化机制》中的一部分，分别从实验、理论和数值模拟三个方面对激波诱导下火焰的稳定性问题进行了系统深入的研究。 在长9.4米，内径32毫米的卧式激波管上，进行了激波与火焰相互作用界面稳定性的实验研究。利用YA—16多闪光高速照相机拍摄该过程的清晰照片，详细讨论了火焰在激波和波后流场作用下失稳、变形和破碎的全过程。 通过建立数学模型定性地讨论了两种不相混的流体之间交界面上小扰动引起的Rayleigh-Taylor和Kelvin-Helmholtz不稳定是否发展的问题，讨论了流体的物理性质对两种不稳定的影响。介绍了界面不稳定性的五个发展阶段，着重讨论了界面不稳定的非线性发展阶段。 基于带化学反应的Navier-Stokes方程和有关的热力学和反应动力学数据，利用改进的VLS格式，对该过程进行了数值模拟，讨论了火焰不稳定性和漩涡生成机理。计算结果表明，激波掠过火团时，分叉形成λ波；前引激波在火团内透射并在轴线处碰撞形成Mach杆，进而逐渐发展为球形激波；火焰在激波作用下先后出现Richtmyer-Meshkov不稳定和Helmholtz不稳定，火焰逐渐变形以致破碎；燃烧速率因此剧增。不同激波马赫数和不同初始组分对激波导致火焰失稳的影响方式不同，结果表明激波马赫数的增加会促进火焰的变形、膨胀，而随着初始混合气中CH₄和O₂的增加火焰燃烧加剧乃至有向爆轰状态发展的趋势。 计算结果与实验现象相吻合表明：本文采用的数值模拟方法是可行的。更多还原

【Abstract】 As a part of a project "enhancement mechanism of focusing shock-flame interactions on deflagration-to-detonation transition", the experimental investigations, theoretical analysis and numerical simulations are carried out to study the flame instabilities induced by shock-flame interactions.Shock-flame interactions experiments are conducted in a horizontal shock tube with 9.4 m long, 32 mm inner diameters. A series of photographs are successfully obtained using a YA-16 high speed camera. The photographs display the flame’s instability, distortion and breakup.The Rayleigh-Taylor and Kelvin-Helmholtz instabilities induced by small disturb in the two unmixed fluids interface are discussed, and the influences by fluids physics properties such as viscidity are also discussed by means of the established mathematical model. And five phases of instabilities development are introduced, especially, the nonlinearity process of the instabilities is analyzed.Based on the Navier-Stokes equations coupled with the chemical reaction terms and some relevant thermodynamic and kinetic data, the interaction between shock wave and flame is investigated numerically using modified Van Leer splitting scheme, flame instability and mechanism of vortex formation are discussed. The calculated results indicate that a bifurcated A. wave can be formed when the shock passes through the flame, and pre-induced shock transmission in the flame leads to the formation of Mach stem, followed by spheral shock wave. The Rayleigh-Taylor and Kelvin-Helmholtz instabilities occurred in the flame induced by shock wave lead to the flame distortion and breakup. The consequent distortion and enlargement of flame surfaces lead to substantial enhancement of the burning rate. The influences of the shock Mach number and initial mass percentage of premixed gas on the interface instabilities are different, the former dominates the enhancement of the flame distortion and enlargement -of flame surfaces, while the latter is contributed to the trend of deflagration to detonation transition.The experimental and calculated results are in good agreement.更多还原