Control of Volumetric Ignition and Thermal-Chemical Instability in Weakly Ionized Plasma for High Pressure Ultra-lean Combustion

先进的贫油内燃机技术可以提高能源效率，减少碳排放。然而，贫燃料混合气的着火失效阻碍了该技术的发展。为了在贫油混合气中实现成功点火，了解发动机中等离子体反应和传播的机理是至关重要的。然而，在可燃混合物中，燃料化学和等离子体相关反应之间的耦合还没有得到详细的研究。在这项研究中，一个合作小组将开发新的理论、计算和实验模型，以了解发生在可燃混合物中的热化学过程的基本机制。如果成功，拟议的研究将提供一个新的经过充分验证的理论模型来模拟发动机中的等离子体驱动反应，特别是在碳和污染物排放减少的超稀薄燃料条件下。开发的等离子体模型也有助于推进其他研究课题，如燃料重整和材料合成。这项研究还将为等离子体科学、燃烧、可持续能源和激光成像的研究生和本科生提供职业发展机会，并加强普林斯顿大学本科生的可持续能源证书计划。拟议的研究将发展：(1)新的热化学不稳定性模型，以了解等离子体收缩中等离子体和正戊烷燃烧化学之间的动力学耦合机制；(2)先进的激光诊断方法，以表征高压下可燃混合物中等离子体不稳定性的动力学和化学过程；(3)经验证的三维计算模型，以模拟燃烧混合物中弱电离等离子体的热化学不稳定性，(4)利用能量级联放电阵列控制等离子体不稳定性，实现超稀薄点火。由此产生的新的热化学不稳定性模型将极大地促进对等离子体燃烧化学对发动机中等离子体不稳定性的动力学影响的理解。电子温度、数密度和电场的实验数据将为理论和数值模型提供关键的验证指标。通过使用不稳定可控能量级联放电阵列的新型体积点火技术将提供一种在贫油条件下高效点火的创新方法。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和更广泛的影响审查标准进行评估，被认为值得支持。

Advanced fuel-lean combustion engine technologies can increase the energy efficiency and reduce the carbon emissions. However, the development of this technology is hindered by the ignition failure in fuel-lean mixtures. To achieve successful ignition in fuel-lean mixtures, understanding of the mechanism of plasma reaction and propagation in engines is critical. However, the coupling between fuel chemistry and plasma-associated reactions in a combustible mixture has not been studied in detail. In this investigation, a collaborative team will develop new theoretical, computational, and experimental models to understand the fundamental mechanism of thermal-chemical processes occurring in combustible mixtures. If successful, the proposed investigation will provide a new well-validated theoretical model to simulate plasma-driven reactions in an engine, especially under ultra-lean fueling conditions with reduced carbon and pollutant emissions. The plasma model developed can also contribute to advancing other research topics, such as fuel reforming and materials synthesis. The research will also provide career development opportunity for graduate and undergraduate students in plasma sciences, combustion, sustainable energy, and laser imaging, and augment the Sustainable Energy certificate program for Princeton undergraduate studentsThe proposed study will develop: (1) a new thermal-chemical instability model to understand the mechanism of kinetic coupling between plasma and n-pentane combustion chemistry in plasma contraction, (2) advanced laser diagnostic methods to characterize the dynamics and chemical process of plasma instability in a combustible mixture at elevated pressure, (3) a validated three-dimensional computational model to simulate thermal-chemical instability of weakly ionized plasma in a combustion mixture, and (4) a novel volumetric ignition technique by controlling plasma instability using an energy cascading discharge array for ultra-lean ignition. The resulting new thermal-chemical instability model will significantly advance the understanding of the kinetic impact of plasma-combustion chemistry on plasma instability in engines. The experimental data of electron temperature, number density, and electric field will provide critical validation targets for the theory and numerical models. The novel volumetric ignition technique by using an instability controlled energy cascading discharge array will provide an innovative method for efficient ignition at fuel lean conditions.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.