CAREER: Kinetic Behavior of Post-Flameout Ignition Events

熄火是飞行器操作中的不利事件，其中燃烧器中的火焰在飞行期间熄灭。它可能发生在极端飞行条件下完全运行的发动机中，为航空带来了关键的安全问题。虽然已经研究了飞机起飞前在地面上的化学点火行为，但对高空熄火后经历的极端条件如何影响点火的基本化学性质知之甚少。该项目将通过调查熄火后重新点火的基本化学过程来填补关键的知识空白，这对于设计有效的工程策略以重新点燃高空失速的飞机发动机是必要的。该项目将使用计算化学方法和基础实验来了解熄火后点火的化学机制，并确定压力和温度如何影响点火行为。它包括强大的教育和推广组件;培训研究生和本科生，在大学和国家一级开发辅导计划，并为燃烧科学教育创建虚拟实验室模块。PI的主要目标是获得对喷气燃料点火化学机理的基本理解，这对于设计新型熄火后点火技术至关重要。她将使用理论和实验相结合的方法来确定如何在起飞和熄火条件下点火的化学途径不同。该项目将解决两个中心研究问题：1）在极端温度和压力条件下，点火机制如何变化？熄火后用热自由基前驱体助推点火的效果如何？将使用电子结构理论方法研究两种不同的喷气燃料替代品（JP-10和POSF 4658替代品），以确定点火的相关反应，计算这些反应发生的速率，并开发燃烧动力学模型，以预测它们在相关温度和压力条件下的化学行为。为了证实理论工作的准确性，本研究将使用补充实验研究通过光电离质谱和红外光谱检测燃烧中间体。此外，还将对自由基前体作为点火促进添加剂的效果进行动力学研究，以评估其作为熄火后再点火的化学解决方案的可行性。该奖项反映了NSF的法定使命，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。

Flameout is an adverse event in aircraft operation in which the flame in the combustor is extinguished during flight. It can occur in fully operational engines under extreme flight conditions, presenting a critical safety issue for aviation. While chemical ignition behavior has been studied for aircraft on the ground before takeoff, far less is known about how the extreme conditions experienced after flameout at high altitude may influence the fundamental chemistry of ignition. This project will help to fill a critical knowledge gap by investigating the fundamental chemistry of post-flameout reignition, which is necessary in designing effective engineering strategies to re-light stalled aircraft engines at altitude. The project will use computational chemistry methods and fundamental experiments to understand the chemical mechanism of post-flameout ignition and determine how pressure and temperature influence the behavior of ignition. It includes strong educational and outreach components; training graduate and undergraduate students, developing mentoring programs at the college and national level, and creating virtual lab modules for combustion science education.The PI’s primary goal is to obtain a fundamental understanding of the chemical mechanism for ignition of jet fuel, which is critical in enabling the design of novel post-flameout ignition technology. She will use a combined theoretical and experimental approach to identify how the chemical pathways for ignition differ at takeoff and flameout conditions. The project will address two central research questions: 1) How does the mechanism for ignition vary at extreme temperature and pressure conditions? and 2) What is the effect of boosting ignition with thermal radical precursors after flameout? Two different jet fuel surrogates (JP-10 and a POSF 4658 surrogate) will be studied using electronic structure theory approaches to determine the relevant reactions for ignition, calculate the rates by which those reactions occur, and develop combustion kinetic models to predict their chemical behavior under relevant temperature and pressure conditions. To confirm the accuracy of the theoretical work, the study will use complementary experimental studies to detect combustion intermediate via photoionization mass spectrometry and infrared spectroscopy. Further, it will conduct a kinetic study of the effect of radical precursors as ignition boosting additives to assess their viability as a chemical solution to post-flameout re-ignition. The resultant fundamental understanding of aviation fuel ignition behavior at extreme conditions and in the presence of radical precursor additives is expected to spur new innovations in aviation safety engineering.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.