The Dynamics of Combustion Systems With Swirl and Vortex Breakdown

9904327 Zvi Rusak这项工作的目标是开发一个经过实验验证的旋流燃烧状态动力学模型，并提供对稀薄预混燃烧系统中导致不稳定性的物理机制的理解。分析将经典的渐近方法与泛函分析、动力系统理论和非线性偏微分方程组理论的现代工具相结合。重点放在燃烧和流动条件上，在这些条件下，可能会发生分叉，并且可能会发展出小幅度或大幅度的不稳定性。边界条件取自实验观测。进行了大量的数值计算，特别是对系统的远离分叉行为进行了研究。理论和数值结果与路易斯安那州立大学的数据进行了比较，以验证模型和代码，并预测了影响燃烧过程的不稳定性或瞬变。在现代低排放系统中，稀薄、预混和旋流预混燃烧系统中的不稳定性给设计带来了严重的限制，特别是当涡流破裂被用来稳定火焰和提高燃烧效率时。

ABSTRACTCTS-9904327 ZVI RUSAK The goal of this effort is the development of an experimentally verified model for the dynamics of combustion states with swirling flows and to provide an understanding of the physical mechanisms leading to instabilities in lean, premixed combustion systems. Analyses combine classical asymptotic approaches with modern tools from functional analysis, dynamical system theory, and the theory of nonlinear partial differential equations. Emphasis is on combustion and flow conditions for which bifurcations may occur and where small- or large-amplitude instabilities may evolve. Boundary conditions are taken from experimental observations. Extensive numerical computations are conducted, in particular of the far-from bifurcation behavior of the system. Theoretical and numerical results are compared with data from Louisiana State University for model and code validation, and from prediction of instabilities or transients that affect the combustion process.Instabilities that develop in lean, premixed combustion systems with swirl present severe design limitations in modern, low-emission systems, especially when vortex breakdown is exploited to stabilize the flame and enhance combustion efficiency.