Session: 04-05 High hydrogen I

Paper Number: 151618

Investigation of Dual-Flame-Front Stabilization in Partially Premixed Hydrogen Flames Using Synchronized PIV/OH-PLIF 

With the growing interest in hydrogen combustion, new combustion technologies are introduced to attain a low-NOx, stable and safe hydrogen combustion. Among those, rich premixing of globally lean combustion can permit robust flame anchoring thanks to the presence of a rich premixed flame front while ensuring low nitrogen oxide emissions through lower flame temperature and low oxygen availability. A second diffusion flame front then finishes combustion. This has the advantage of avoiding thermodiffusive instabilities that occur when hydrogen burns in a lean regime as the Markstein number of hydrogen goes from negative (the flame accelerates with stretch) in the lean domain to positive (the flame decelerates with stretch) in the rich domain. In addition, the high stretch resistance of hydrogen allows for quick mixing of air to return to globally lean conditions using swirl.  We combine this injection method with a dual swirl injector. The variety of flame structures with varying swirl was previously observed with OH* chemiluminescence and the injection scheme was shown to achieve low nitrogen oxide emissions. While this technology is promising, few things are known about the interaction between the premixed and diffusion flame fronts or about the effect of the flame on the flow field. The present work uses synchronized Stereo-Particle Image Velocimetry (S-PIV) and OH-Planar Laser Induced Fluorescence (OH-PLIF) to investigate in detail the flames produced using this injection mode. S-PIV allows visualization of the three components of the velocity field, while OH-PLIF gives the instantaneous contour of the flame; therefore, synchronizing the diagnostics uncovers the interactions between the two flame fronts and the flow. In this study, we focus our analysis on two flame archetypes, differing only by the intensity of swirl in the central channel. The observations highlight the importance of swirl in defining the flame structure, while also giving elements to explain differences in NOx formation dynamics.

Presenting Author: Maxime Leroy EM2C /Safran Tech

Presenting Author Biography: Maxime obtained his Master's degree in Engineering from CentraleSupélec in 2021, he has since been studying novel hydrogen combustion technology for his PhD under a joint Safran Tech and EM2C Laboratory.

Authors:

Maxime Leroy EM2C /Safran Tech
Clément Mirat Laboratoire EM2C
Antoine Renaud Laboratoire EM2C
Stefano Puggelli Safran Tech
Ronan Vicquelin Laboratoire EM2C