CAREER: Kinetic Behavior of Post-Flameout Ignition Events

University Of Colorado At Boulder, Boulder CO

Investigators

Abstract

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.