Quantitative Measurements of Temperature and Species in Counterflow Flames Near Extinction

濒临灭绝的逆流火焰中温度和物种的定量测量

• 批准号: 2027740
• 负责人: Robert Lucht
• 金额: $ 33万
• 依托单位: Purdue University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2020
• 资助国家: 美国
• 起止时间: 2020-10-01 至 2024-09-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2027740&HistoricalAwards=false
• 关键词: Quantitative; Measurements; Temperature; Species; Counterflow

Accurate measurements of temperature are critical for improving our understanding and modeling of flame structure and pollutant formation in flames. Modern computational models of both laminar and turbulent flames incorporate detailed models of chemical reaction kinetics and transport processes. The rates of chemical reactions in particular can exhibit strong temperature dependence. Consequently, accurate and validated methods for measuring flame temperatures are critical for rigorous comparison of numerical calculations of flame structure and pollutant formation with experiment. Coherent anti-Stokes Raman scattering (CARS) spectroscopy is widely considered to be the most accurate temperature measurement technique for flames but it is difficult to assess accurately the absolute temperature accuracy of the method, mostly because of the lack of other validated methods for measuring temperatures in excess of 2000 K. In this work a rigorous theoretical analysis of the accuracy of temperature measurements using the laser diagnostic method CARS spectroscopy will be performed. In addition, a new type of CARS experimental system will be developed to eliminate some factors which cause increased uncertainty in CARS temperature measurements. The goal of the project is to demonstrate temperature measurement accuracies of better than one per cent, which will enable rigorous evaluation of important aspects of computational flame models. Temperatures will be measured in both near-adiabatic Hencken burner flames and in non-premixed counterflow flames using an advanced high-spectral-resolution scanning CARS system. These measurements are enabled by the recent acquisition by our group of a high-power, single-frequency-mode, tunable titanium:sapphire continuous-wave laser system. The spectral width of the CARS laser beams will be approximately an order of magnitude less than the spectral width of the Raman lines for species such as N2 and H2. Consequently, we will be able to resolve the CARS spectral lines, minimizing the effects of the uncertainties their linewidths. The impact of the vibration-rotation interactions (the Herman-Wallis effect) and the effect of vibrational anharmonicity on the accuracy of temperatures extracted from N2 and H2 CARS spectra will be theoretically investigated. The accuracy of the high-spectral-resolution CARS temperature measurements will be validated in near-adiabatic Hencken burner flames. The validated CARS temperature measurements will then be performed in laminar, counterflow, non-premixed hydrocarbon/air flames, emphasizing measurements of flame structure near extinction.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

准确的温度测量对于提高我们对火焰结构和火焰中污染物形成的理解和建模至关重要。 层流和湍流火焰的现代计算模型包含化学反应动力学和传输过程的详细模型。 化学反应的速率尤其表现出强烈的温度依赖性。 因此，准确且经过验证的火焰温度测量方法对于火焰结构和污染物形成的数值计算与实验的严格比较至关重要。 相干反斯托克斯拉曼散射 (CARS) 光谱被广泛认为是最准确的火焰温度测量技术，但很难准确评估该方法的绝对温度精度，主要是因为缺乏其他经过验证的温度测量方法超过 2000 K。在这项工作中，将对使用激光诊断方法 CARS 光谱法进行温度测量的准确性进行严格的理论分析。 此外，还将开发一种新型的CARS实验系统，以消除一些导致CARS温度测量不确定性增加的因素。 该项目的目标是证明温度测量精度优于百分之一，这将使计算火焰模型的重要方面得到严格评估。 将使用先进的高光谱分辨率扫描 CARS 系统在近绝热 Hencken 燃烧器火焰和非预混逆流火焰中测量温度。 这些测量是通过我们团队最近购买的高功率、单频模式、可调谐钛：蓝宝石连续波激光系统实现的。 CARS 激光束的光谱宽度将比 N2 和 H2 等物质的拉曼线光谱宽度小大约一个数量级。 因此，我们将能够解析 CARS 谱线，最大限度地减少线宽不确定性的影响。 将从理论上研究振动-旋转相互作用（赫尔曼-沃利斯效应）和振动非谐性对从 N2 和 H2 CARS 光谱中提取的温度精度的影响。 高光谱分辨率 CARS 温度测量的准确性将在近绝热 Hencken 燃烧器火焰中得到验证。 然后，经过验证的 CARS 温度测量将在层流、逆流、非预混合碳氢化合物/空气火焰中进行，强调对接近熄灭的火焰结构的测量。该奖项反映了 NSF 的法定使命，并通过使用基金会的智力优势进行评估，被认为值得支持以及更广泛的影响审查标准。

项目成果

A Study of the Effects of Steam Addition on Ammonia Hydrogen Air Combustion

蒸汽添加对氨氢空气燃烧影响的研究

• 发表时间: 2022-05
• 期刊: 2022 Spring Technical Meeting Central States Section of The Combustion Institute
• 作者: Bhaduri, Sreetam;Gore Jay P.
• 通讯作者: Gore Jay P.