Physics-based predictive modeling for ultra-low-emission combustion technology

低排放动力和推进系统的前瞻性技术依赖于高度稀释的低温燃烧。低温燃烧可以防止氮氧化物的形成，但由于缺乏理解和预测模型，在汽车和航空航天应用中尚未实现。这项研究将探索在这种高度稀释的条件下，确保燃料能源稳定、高效和清洁转化的基本流体动力学过程。两个互补的技术应用激发了这项研究。首先是“分注”策略的应用，汽车行业的合作伙伴正在研究这一策略。这些策略采用大量单独的燃油喷射事件，以精确控制时间和速度的热量释放和污染物的形成。第二种应用是将高度稀释的反应物注入到循环燃烧产物的流动结构中。这一过程是项目合作伙伴罗尔斯·罗伊斯公司开发低排放航空发动机的基础——实际上，它是燃烧系统总体发展的基础。采用高端的科学计算方法进行全分辨率数值实验，旨在解释劈裂喷射的流体动力学、混合动力学和化学动力学之间的关系。首次将年龄概念应用于实验分析；混合物的年龄或停留时间是理解动力学受限燃烧过程（如自燃、高度稀燃、NOx和烟灰颗粒形成）如何演变的自然参考量。一个基于流体时代概念的新型建模框架将被开发出来，随后其超低排放燃烧系统设计的潜力将在汽车和航空航天应用中得到证明。

Prospective technologies for low-emission power and propulsion systems rely on highly dilute, low-temperature combustion. Low-temperature combustion prevents formation of oxides of nitrogen, but it has not been achieved in automotive and aerospace applications due to lack of understanding and predictive models. This study will probe the fundamental fluid dynamic processes which are critical to ensure stable, efficient, and clean conversion of fuel energy under such highly dilute conditions. Two complementary technological applications motivate this study. The first is application of 'split-injection' strategies, which are being investigated by partners in the automotive industry. These strategies employ large numbers of separate fuel-injection events in order precisely to control the timing and rate of heat release and pollutant formation. The second application is the injection of highly dilute reactants into a flow structure that recirculates combustion products. This process underpins low-emission aero-engine development by project partner Rolls-Royce - indeed it is fundamental to the development of combustion systems in general. High-end scientific computing methods will be employed to perform full-resolution numerical experiments, designed to explain the relationship between the fluid-, mixing-, and chemical-dynamics of split-injection. For the first time, the age concept will be used in the analysis of these experiments; the age, or residence time, of a mixture is a natural reference quantity for understanding how kinetically limited combustion processes (e.g. autoignition, highly-dilute combustion, NOx and soot-particle formation) evolve. A novel modelling framework, built on this concept of fluid age will be developed and subsequently its potential for the design of ultra-low-emission combustion systems will be demonstrated in automotive and aerospace applications.