Watery Fuel Diffusion Flames

目前，全球90%的能源利用来自化石燃料的燃烧，在可预见的未来，这种使用预计不会在全球范围内下降。因此，改善燃烧性能以提高燃油效率和减少有害污染物的排放是很重要的。经典的火三角形表明，要发生持续的燃烧，必须有热量、燃料和氧化剂的供应；其中任何一种物质的减少都可能使火焰燃烧不那么强烈，这可能导致温度下降，火焰波动增加，最终火焰熄灭。有趣的是，有时这些几乎熄灭的火焰表现出最高的燃烧性能（即高效率和低排放）。由于水通常用于熄灭不需要的火焰，因此确定适量的水是否可能产生高性能的近熄灭燃烧是很重要的。此外，一些下一代燃料的含水量非常高，自然会产生同样的近乎灭绝的行为。提出的研究探讨了水在非预混火焰中作为燃料侧反应物引入时的作用。这项工作的广泛科学和技术影响包括提高对自然或人为掺入水以操纵燃烧过程的系统的燃烧化学的理解。本项目对对可持续能源感兴趣的本科生、研究生和国际学者具有重要价值；它将包括各级学生的研究参与，以及扩大专业合作的机会。该项目还将扩大代表性不足的少数民族在STEM领域的参与，并作为美国国家科学基金会资助的路易斯-斯托克斯少数民族参与联盟（LSAMP）的一部分。这项工作的技术重点是探索水在1-50大气压和操作条件之间的压力范围内，使用共流射流和逆流燃烧器配置扩散火焰中的作用。这项工作将特别关注由于水的加入而导致的火焰熄灭，这大大降低了火焰温度并稀释了燃料-空气混合物。测量包括火焰温度和参与抑制燃烧的重要自由基的浓度。测量温度的方法将包括热电偶、细丝高温法和相干反斯托克斯拉曼光谱（CARS）。OH和CO的定性测量将采用平面激光诱导荧光。实验结果将与计算流体动力学计算以及大气和高压条件下的详细化学动力学计算进行比较。实验与计算相结合，全面揭示了水在控制燃烧中的作用。

1605533 - Dunn-RankinCurrently, 90% of worldwide energy utilization comes from the combustion of fossil fuels, and this use is not expected to decline worldwide for the foreseeable future. Consequently, improvements in combustion performance to increase fuel efficiency and reduce the emission of harmful pollutants are important. The classical fire triangle shows that for sustained combustion to occur, heat, fuel, and a supply of oxidizer must be present; a reduction of any of these can make a flame burn less robustly, which may result in a decrease in temperature, an increase in flame fluctuations, and ultimately flame extinction. Interestingly, sometimes these nearly extinguished flames exhibit the highest combustion performance (i.e., high efficiency and low emissions). Since water is commonly used to extinguish unwanted flames, it is important to determine if just the right amount of water can potentially produce high performance near-extinction combustion. In addition, some next-generation fuels have very high water content that can naturally produce this same near-extinction behavior. The proposed research explores the role of water when it is introduced as a fuel side reactant in a non-premixed flame. The broad scientific and technical impact of this work includes an improved understanding of combustion chemistry of systems that incorporate water naturally or artificially to manipulate the combustion process. The project is of great value to undergraduates, graduates, and international scholars interested in sustainable energy; it will incorporate research participation for students at all levels, as well as opportunities to extend professional collaborations. The project will also broaden the participation of underrepresented minorities in STEM fields and as part of the NSF-funded Louis-Stokes Alliance for Minority Participation (LSAMP).The technical focus of the work is to explore the role of water, over a range of pressures between 1-50 atm and operating conditions, in diffusion flames using a co-flow jet and counter-flow burner configuration. This work will look specifically at flame extinction due to the addition of water, which significantly reduces flame temperature and also dilutes the fuel-air mixture. Measurements include flame temperature and concentrations of important radical species involved in inhibiting combustion. The methods for measuring temperature will include thermocouples, thin filament pyrometry, and Coherent anti-Stokes Raman spectroscopy (CARS). Qualitative measurements of OH and CO will employ planar laser induced fluorescence. Experimental results will be compared with computational fluid dynamic calculations and with detailed chemical kinetics calculations for both atmospheric and high pressure conditions. The combination of experiments and calculation will expose comprehensively the role of water in controlling combustion.