Structure, propagation, and stabilization of turbulent flames at aircraft engine conditions

气候变化对地球上的生命构成了生存威胁。虽然大多数温室气体（GHG）排放者都有一些可能的替代品，但由易于获得的具有特殊能量密度的液体燃料提供动力的商用远程飞机发动机尚未实现零GHG排放解决方案。这种情况突出表明迫切需要最大限度地提高效率，从而减少飞机发动机的燃料消耗和排放。通过增加总压力比，相应地增加燃烧室中的压力和温度，可以实现效率的逐步增加。H2也被认为是一种零温室气体排放的航空燃料。任何一种解决方案都涉及极端的工程，需要基础研究投入，以确保安全运行，使持续，稳定的燃烧和火焰稳定，而不会自燃，回火或井喷，这将在极端和广泛变化的发动机热力学状态下加剧。在这样的高压-高温发动机工作条件下，对湍流修正火焰速度、火焰结构、传播模式和吹出机制所需的测量仍然是难以捉摸的。 拟议的计划将提供全面的测量，科学的基础，和模拟的本地和全球的火焰速度和结构，火焰传播模式和制度，和吹出机制的旋流稳定，湍流预混火焰在飞机发动机条件。为此，实验将进行压力高达25巴，入口温度高达700 K，并在湍流雷诺数高达68000与亚临界，超临界喷气燃料，和H2。在加拿大的大学中是独一无二的，在世界各地也只有很少的同类项目-UTIAS新建的高压燃烧研究设施（HPCRF）使拟议的研究计划成为可能。这将解决湍流燃烧的一些最深刻的问题，同时为下一代飞机发动机的设计输入服务。具体而言，高速断层粒子图像测速，化学发光成像，和最近开发的火焰粒子跟踪算法将被用来测量本地和全球的火焰速度。通过拉格朗日流体粒子跟踪法在小尺度下获得的湍流扩散系数，结合高速激光诱导荧光和拉曼散射，将产生湍流火焰结构。高保真计算辅助实验诊断将描绘不同的火焰传播模式和相应的制度。最后，H2-空气湍流燃烧实验和收集到的见解将最终成为零温室气体排放航空发动机的新燃烧室。 除了深远的工程影响外，在该计划中培训的高素质人员将在HPCRF拥有无与伦比的研究经验，这将使他们成为碳中和航空航天推进的下一代领导者。

Climate change poses an existential threat to life on earth. While most greenhouse gas (GHG) emitters have some possible alternatives; commercial, long-range aircraft engines powered by easily accessible liquid fuels of exceptional energy density, are yet to realize zero GHG-emission solutions. Such a situation underscores the urgent need to maximize efficiency, thereby reduce fuel consumption and emissions from aircraft engines. A step increase in efficiency can be achieved by correspondingly increasing the pressure and temperature in the combustor by increasing the overall pressure ratio. H2 is also being seriously considered as a zero GHG-emission aviation fuel. Either solution involves extreme engineering which behooves fundamental research inputs to ensure safe operation by enabling sustained, stable combustion, and flame stabilization without autoignition, flashback, or blowoff, which would be exacerbated in the extreme and widely varying engine thermodynamic states. The required measurements for turbulence modified flame speeds, flame structure, propagation modes, and blowoff mechanisms at such high pressure-temperature, engine operating conditions remain elusive. The proposed program will provide comprehensive measurements, scientific underpinnings, and modeling of local and global flame speeds and structure, flame propagation modes and regimes, and blowoff mechanisms of swirl-stabilized, turbulent premixed flames at aircraft engine conditions. To this end, experiments will be conducted at pressure up to 25 bar, inlet temperature up to 700 K, and at turbulence Reynolds numbers up to 68000 with both subcritical, supercritical jet fuels, and H2. Unique in Canadian universities and only very few of its kind around the world - the newly constructed High-Pressure Combustion Research Facility (HPCRF) at UTIAS enables the proposed research program. This will address some of the most profound questions of turbulent combustion, all the while serving design inputs for next-generation aircraft engines. Specifically, high-speed tomographic particle image velocimetry, chemiluminescence imaging, and the recently developed Flame Particle Tracking algorithms will be utilized to measure the local and global flame speeds. Turbulent diffusivity obtained by Lagrangian Fluid Particle Tracking at small scales, combined with high-speed laser induced fluorescence and Raman scattering will yield the turbulent flame structure. High fidelity computation aided experimental diagnostics will delineate the different flame propagation modes and corresponding regimes. Finally, H2-air turbulent combustion experiments and the insights gleaned will culminate into new combustors for zero GHG-emission aircraft engines. Alongside the far-reaching engineering impact, the highly qualified personnel trained in this program will have an unmatched research experience at HPCRF, which will prepare them to emerge as next-generation leaders of carbon-neutral aerospace propulsion.