CAREER: Steady and Transient Dynamics of Catalyst-Assisted Combustion in Micro-Scale Power Generators

广泛使用MEMS和其他微尺度器件的主要限制是合适的电源的可用性。 由于其高能量密度，燃烧是一种有吸引力的动力源，但存在主要的技术挑战，包括冷启动点火和持续燃烧的控制。 鉴于微燃烧室固有的高表面积与体积比，使用非均相催化反应来促进点火和扩展可燃性极限具有吸引力。 这是一个计算和实验研究的物理和化学过程相关的这一战略。先进的计算方法的开发和验证与实验测量和参数的研究是专门针对小规模的燃烧系统。 研究了两种典型构型。 首先，通过修改现有的瞬态一维驻点流动代码与详细的表面和气相化学动力学的催化表面上的驻点流动进行了分析。 参数研究解决了各种燃烧制度，改进的点火和熄火限制，由于催化反应，和整体燃烧性能。 此外，瞬态调制的表面温度和入口流量的影响进行了研究，作为一个潜在的控制方法。 其次，微通道燃烧室建模开发高保真多维直接模拟代码提供详细的时间和空间信息的燃烧室过程。 非预混燃烧模式（使用同轴供应的燃料和氧化剂）作为一种手段，提高点火和发热的可行性进行了评估。 对于这两种配置，温度分布和产品种类组成的实验测量值与计算结果进行比较，以验证嵌入的submodels.As教育计划，交互式计算流体动力学（CFD）工具是专为本科生和研究生在热流体科学。 其中包括与广泛使用的动力学模拟软件包兼容的应用软件包和用于求解微分方程和模拟反应流数据的网络工具。

A major limitation to the wide use of MEMS and other micro-scale devices is the availability of suitable power sources. Combustion is an attractive power source because of its high energy density, but there are major technical challenges including ignition from cold start and control of sustained combustion. Given the high surface-to-volume ratio inherent in a microcombustor, there is attraction in using heterogeneous catalytic reactions to promote ignition and to extend flammability limits. This is a computational and experimental study of the physical and chemical processes relevant to this strategy.Advanced computational methods are developed and validated with experimental measurements and parametric studies are done specifically targeted at small-scale combustion systems. Two canonical configurations are studied. First, stagnation-point flow over a catalytic surface is analyzed by modifying existing transient one-dimensional stagnation-point flow code with detailed surface and gas-phase chemical kinetics. Parametric studies address various combustion regimes, modified ignition and extinction limits due to catalytic reaction, and overall combustion performance. Also, the effects of transient modulation of the surface temperature and inlet flow are investigated as a potential control methodology. Second, a microchannel combustor is modeled by developing a high-fidelity multidimensional direct simulation code providing detailed temporal and spatial information on the combustor process. The feasibility of a nonpremixed combustion mode (using a coaxial supply of fuel and oxidizer) as a means of enhancement of ignition and heat generation is assessed. For both configurations, experimental measurements of temperature distribution and product species compositions are compared with computational results to validate embedded submodels.As an education program, interactive computational fluid dynamics (CFD) tools are designed for undergraduate and graduate students in thermo-fluid sciences. These include application packages that are compatible with widely used kinetic simulation packages and web-based tools for solving differential equations and simulating data on reacting flows.