Molecular Transport and Kinetics in Hydrogen-Fueled Cellular and Non-Cellular Flames

1134268pitzh原子在氢（H2）和烃（HC）燃烧化学动力学中起主导作用，通过链分支步骤H + O2 OH + O，其速率强烈地决定了火焰速度和整体燃料/空气反应速率。准确预测h原子输运对于H2、HC燃料以及生物燃料的准确燃烧特性至关重要。然而，h原子输运的预测仍然存在很大的不确定性。更精确的h原子输运模型已经提出，但很少实现，也没有通过火焰结构测量来验证。在实际燃烧条件下，火焰中h原子的定量测量很少。在拉伸和弯曲火焰中，H原子的传递尤为重要，因为H原子（和其他轻气体如H2）的优先扩散非常强烈，并且极大地影响火焰温度、熄灭极限和细胞火焰形成的设定。高度弯曲和拉伸的火焰细胞可以超越正常的一维消光极限，而h原子的快速扩散是火焰存活的必要条件。管状燃烧器产生高度弯曲和拉伸的火焰，是研究h原子传输的理想选择，这将导致先进和有效的分子传输模型。可以研究均匀拉伸和均匀曲率下的预混和非预混火焰，其中整体拉伸和曲率可以独立变化。在高拉伸和高曲率下，h原子的优先扩散将是最强的，h原子的分布可以在Vanderbilt的光学可及燃烧器上用h原子LIF测量。高局部曲率增强了h原子的优先扩散，可以研究拉伸的胞状火焰。利用h原子LIF和拉曼散射测量了管状燃烧器在极端条件下形成的火焰细胞，并将数据与具有先进h原子分子输运的详细3D CFD模型进行了比较。智力优势：在本提案中，我们将在h2燃料的管状火焰中验证先进的h原子（和小而轻的分子）传输模型。h原子分布将在氢燃料非预混和预混管火焰中测量，以验证先进的分子传输代码。利用拉曼位移ArF激光器对h原子进行定量的双光子LIF测量。h原子LIF淬火将从亨肯燃烧器中的h原子LIF测量中进行校正，该测量与管状燃烧器中火焰浴气体的拉曼测量相关。OH浓度将用用拉曼散射淬火校正的OH liff信号来测定。H/OH自由基比（对H原子传输非常敏感）将在实验和模型之间进行比较，以验证先进的分子传输代码。中国厦门大学的王培勇博士将把精确的h原子分子输运模型应用到一维和三维模拟中。将研究细胞和非细胞管状火焰，以验证在各种环境下精确的h原子输运。最终的结果将是一个先进的经过验证的分子传输代码，可用于各种燃烧H2、HC和生物燃料的燃烧设备（燃气轮机、锅炉、发动机），以提高可靠性、安全性和效率。更广泛的影响：包括少数民族在内的研究生和本科生将接触到最新的计算机模拟和激光诊断设备。工程师将指导当地高中生进行工程设计项目和研究。厦门大学和范德比尔特大学的学生将交换在实验和计算燃烧方面的全球研究经验，并促进亚洲和美国的互动。在范德比尔特大学的教师研究经验项目下，纳什维尔当地的高中教师将在夏天参与激光诊断和燃烧研究。

1134268PitzH-atoms play a dominate role in hydrogen (H2) and hydrocarbon (HC) combustion chemical kinetics through the chain branching step H + O2 OH + O whose rate strongly dictates flame speeds and overall fuel/air reaction rates. Accurate prediction of H-atom transport is essential to give accurate flame properties for combustion of H2, HC fuels as well as bio-fuels. However, great uncertainties in the prediction of H-atom transport remain. More accurate H-atom transport models have been proposed but are seldom implemented and have not been validated by flame structure measurements. There are few quantitative H-atom measurements in flames under realistic combustion conditions. H-atom transport is particularly important in stretched and curved flames where preferential diffusion of the H atoms (and other light gases such as H2) is very strong and greatly affects flame temperature, extinction limits and the on-set of cellular flame formation. Highly curved and stretched flame cells can survive beyond normal 1D extinction limits and fast diffusion of H-atoms is essential to the flame survival. The tubular burner creates a highly curved and stretched flame that is ideal for the study of H-atom transport that will lead to advanced and validated molecular transport models. Premixed and non-premixed flames can be studied under uniform stretch and curvature where the overall stretch and curvature can be varied independently. At high stretch and curvature, preferential diffusion of H-atoms will be the strongest and the H-atom distributions can be measured in Vanderbilt's optically accessible burner with H-atom LIF. Stretched cellular flames can be studied with high local curvature that enhances H-atom preferential diffusion. The flame cells formed at extreme conditions in the tubular burner can be measured with H-atom LIF and Raman scattering and the data compared to detailed 3D CFD models with advanced H-atom molecular transport. Intellectual Merit: In this proposal, we will validate advanced H-atom (and small, light-weight molecule) transport models in H2-fueled tubular flames. H-atom profiles will be measured in hydrogen-fueled non-premixed and premixed tubular flames to validate advanced molecular transport codes. Quantitative 2-photon LIF measurements of H-atoms will be developed using a Raman-shifted ArF laser. The H-atom LIF quenching will be corrected from H-atom LIF measurements in a Hencken burner that are correlated to Raman measurements of flame bath gases in the tubular burner. OH concentrations will be determined with OH LIF signals that are quenching corrected with Raman scattering. The H/OH radical ratio (found to be very sensitive to H atom transport) will be compared between experiment and model to validate the advanced molecular transport code. Accurate H-atom molecular transport models will be implemented into 1D and 3D simulations by Dr. Peiyong Wang at Xiamen University in China. Cellular and non-cellular tubular flames will be studied to validate accurate H-atom transport in a variety of environments. The ultimate outcome will be an advanced validated molecular transport code that can be used in a wide variety of combustion devices (gas turbines, boilers, engines) burning H2, HC and bio-fuels to improve reliability, safety and efficiency.Broader Impacts: Graduate and undergraduate students including underrepresented minorities will be exposed to the latest computer simulation and laser diagnostic facilities. Engineers will mentor local high school students in engineering design projects and research. Students from Xiamen University and Vanderbilt University will be exchanged to gain global research experiences in experimental and computational combustion and promote Asian-US interactions. Local Nashville high school teachers will be involved in laser diagnostic and combustion research in the summer under the Research Experience for Teachers Program at Vanderbilt University.