CAREER: Compressive Laser Absorption Spectroscopy for Supercritical Combustion Studies

下一代超清洁、高效的内燃机有望在比现在的发动机更高的压力下运行。不幸的是，人们对高压下的燃烧物理和化学知之甚少，这阻碍了更清洁、更省油的发动机（包括汽车、柴油、喷气和火箭发动机）的发展。因此，该项目的首要目标是更好地了解极端压力下的燃烧。一种新的激光诊断方法用于研究极端压力下燃烧的基本化学和辐射特性，针对与当前和未来发动机发展相关的特定燃料和操作条件。该项目的成功完成将产生：(1)一种新的、广泛适用的诊断工具，将加速在一个至关重要但尚未开发的高压领域的基础燃烧研究；(2)对这些条件下点火和污染物形成的基本化学原理有了新的认识。补充教育活动将利用现代媒体技术来测试实验室研究在课堂上的整合，并吸引大学以外更广泛的群体参与当前与能源和燃烧相关的科学和工程挑战。该项目的一个挑战和研究重点是超临界热力学条件下的燃烧，其中反应流体既不是液体也不是气体，并且表现出难以建模的非理想行为。为了研究这种状态下的非平衡过程，介绍了一种实验方法，该方法将先进的信号压缩理论应用于波长域，以便在超临界压力下进行基于激光吸收的物质和温度测量。该方法可用于中远红外波段的广谱测量或较窄波长范围内的超快速传感。因此，该项目涉及对基础高温光谱研究和激波管内原位物种测量方法的重新检查，并启用新的探索方法，利用新型测量技术的优势。可以设想，当压缩感知方法与高压、高重复率激波管协同结合时，将(1)扩展和/或允许建立新的光谱数据库，以包括极端压力，(2)实现新的燃烧化学研究，分离超临界状态下的高压反应动力学。提出了一项研究计划，以测试压缩传感技术的变化，研究超临界流体的光谱特性，并研究高压点火和烟灰形成的化学动力学。

The next generation of ultra-clean, efficient combustion engines are expected to operate at much higher pressures than today's engines. Unfortunately, combustion physics and chemistry are poorly understood at these high pressures, which has slowed the advancement of cleaner, more fuel-efficient engines (including automotive, diesel, jet, and rocket engines). Therefore, the overarching goal of this project is to better understand combustion at extreme pressures. A new laser diagnostic method is used to investigate fundamental chemistry and radiative properties of combustion at extreme pressures, targeting specific fuels and operating conditions relevant to current and future engine development. Successful completion of the project will yield (1) a novel, broadly-applicable diagnostic tool that will accelerate basic combustion research in a critically important, but largely unexplored high-pressure domain, and (2) new insights into the fundamental chemistry of ignition and pollutant formation at these conditions. Complementary educational activities will leverage modern media technologies to test the integration of laboratory research in the classroom and to engage broader groups outside the university in current scientific and engineering challenges related to energy and combustion.A challenge and research focal point of this project is combustion at supercritical thermodynamic conditions, where the reacting fluid is neither liquid or gas and exhibits non-ideal behavior that is difficult to model. To study non-equilibrium processes in this regime, an experimental method is introduced that adapts advanced theories of signal compression to the wavelength domain in order to conduct laser absorption-based measurements of species and temperature at supercritical pressures. The proposed method can be used to perform broad spectral surveys of the mid- to far-infrared domain or ultra-fast sensing in a narrower wavelength range. Accordingly, this project involves a re-examination of the approaches to fundamental high-temperature spectroscopy studies and in situ species measurements in shock tubes, and enables new exploratory approaches that leverage the strengths of the novel measurement technique. It is envisioned that the compressive sensing method, when synergistically combined with a high-pressure, high repetition-rate shock tube, will (1) extend and/or allow the building of new spectroscopic databases to include extreme pressures, and (2) enable new combustion chemistry studies that isolate high-pressure reaction kinetics in the supercritical regime. A research plan is set forth to test variations of the compressive sensing technique, investigate spectroscopic properties of supercritical fluids, and examine chemical kinetics of high-pressure ignition and soot formation.