RUI: Indirect Measurement of Reaction Rates in Laminar Flames

与燃烧化学相关的化学反应速率通常通过理论计算或直接实验来确定。与所有实验一样，这些实验也有局限性。在一种常用的装置（快速压缩机）中，测量是在与发动机点火有关的条件下进行的——中等温度和高压。在另一种最常用的设备（激波管）中，测量可以达到更高的温度，但是它们通常限于非常低的反应物浓度。我们将在这些装置无法达到的条件下使用火焰间接测定反应速率。这种测量将在比快速压缩机更高的温度和比激波管更高的反应物浓度下进行。与燃烧化学有关的反应速率通常是通过理论计算或直接实验确定的。与所有实验一样，这些实验，如激波管（ST）和快速压缩机（RCM）测量，都有局限性。RCM测量在与发动机点火有关的条件下是有价值的——中温和高压。ST测量可以达到更高的温度，但它们通常限于低反应物浓度，以及不代表火焰化学的自由基池。我们提出了一个新的实验活动来测量层流火焰速度使用中尺度发散通道在混合条件下，该量是敏感的目标基本反应速率。然后，我们将使用这些火焰速度测量来改进目标反应速率的表征。这代表了使用火焰速度对反应速率的间接实验测量，这是一种不常见的提取反应速率的方法，我们已经在以前的工作中成功地证明了这一点。使用内部的开源软件包，我们确定了常压下富乙烯火焰的层流火焰速度对三个反应敏感。我们目前正在建设一个大气压力发散的中尺度通道，提出的项目将资助在该通道中在良好的量化条件下测量层流火焰速度的验证，以及上述反应的富乙烯火焰。然后，我们将使用测量作为验证和优化目标，以改进在文献中实验测量有限的温度下这三种反应速率的表征。如果成功，这个项目将导致未来的实验活动，目标是通过测量层流火焰速度的其他反应。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Chemical reaction rates that are relevant to combustion chemistry are typically determined using theoretical computations or direct experiments. As with all experiments, these have limitations. In one commonly used setup (rapid compression machine), measurements are performed at conditions relevant to ignition in engines – intermediate temperatures and high pressures. In the other most commonly used device (shock tube), measurements can access a higher temperature, however they are typically limited to very low reactant concentrations. We will indirectly determine reaction rates at conditions that are inaccessible to these devices by using a flame. This measurement will occur at higher temperatures than the rapid compression machine and higher reactant concentration than the shock tube. Reaction rates that are relevant to combustion chemistry are typically determined using theoretical computations or direct experiments. As with all experiments, these experiments, such as shock tube (ST) and rapid compression machine (RCM) measurements, have limitations. RCM measurements are valuable at conditions relevant to ignition in engines – intermediate temperatures and high pressures. ST measurements can access a higher temperature, however they are typically limited to low reactant concentrations, and a radical pool that is not representative of flame chemistry. We propose a new experimental campaign to measure the laminar flame speed using a mesoscale diverging channel at mixture conditions where this quantity is sensitive to targeted elementary reaction rates. We will then use those flame speed measurements to improve characterization of the targeted reaction rates. This represents indirect experimental measurements of reaction rates using flame speed, an uncommon method to extract reaction rates that we have successfully demonstrated in previous work. Using an in-house, open-source software package, we have determined that the laminar flame speed for rich ethylene flames at atmospheric pressure is sensitive to three reactions. We are currently constructing an atmospheric pressure diverging meso-scale channel, and the proposed project would fund validation of laminar flame speed measurement in this channel at well-quantified conditions, as well as rich ethylene flames the mentioned reactions. We will then use the measurements as validation and optimization targets to improve characterization of these three reaction rates at temperatures where there are limited experimental measurements in the literature. If successful, this project will lead to future experimental campaigns targeting other reactions by measuring laminar flame speed.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.