Session: 04-13: Kinetics

Paper Number: 82069

82069 - High-Fuel Loading Ignition Delay Time Characterization of Hydrogen/Natural Gas/Ammonia at Gas Turbine-Relevant Conditions Inside a High-Pressure Shock Tube 

Due to the increasingly challenging carbon emission reduction targets, hydrogen-containing fuel combustion is gaining the energy community's attention, as highlighted recently in the Department of Energy’s (DOE) Hydrogen Program Plan. Though fundamental and applied research of hydrogen-containing fuels has been a topic of research for several decades, there are knowledge gaps and unexplored fuel blend combustion characteristics at conditions relevant to modern gas turbine combustors. Hydrogen will be burned directly or as mixtures with natural gas (NG) and/or ammonia (NH₃) in these devices. While there have been numerous H₂ studies, very little have used hydrogen addition in natural gas (NG) with high-fuel loadings (6-14%) to simulate actual gas turbine mixtures. To our knowledge, no high-fuel loading studies have been performed at high pressures (20-30 bar) that would be relevant to gas turbine operating conditions. Therefore, it is necessary to obtain ignition data that would provide useful insight for H₂/NG/Air mixtures in addition to validating and building upon current chemical kinetic mechanisms.

This study was conducted using the UCF’s High-Pressure Extended Range Shock Tube for Advanced Research (HiPER-STAR), which is a newly built shock tube facility capable of reaching pressures of 1000 atm. Experiments were performed between 20-30 bar and had a temperature range of 800-2000 K. The ignition delay times (IDTs) were captured using radical chemiluminescent emission detectors, and the species time histories of NO_x and CO_x were observed using mid-infrared laser absorption spectroscopy. The equivalence ratio was varied between 0.3-1.2 to show lean conditions, and the amount of H₂ addition ranged between 10-90%. Initial experiments have shown detonation spikes reaching 500 bar as well as signs of pre-combustion phenomenon occurring, especially on the lower half of the temperature scale. This phenomenon leads to uncertainty in the interpretation of IDTs, and therefore this issue must be addressed and resolved if accurate times are to be reported. High-fuel loading experiments in previous literature have shown the same issue and have suggested techniques to characterize the pressure rise before ignition. The most common solution is to dilute the fuel mixture with a non-reactive molecule (most commonly argon or nitrogen). However, dilution can lower the fuel loading outside of relevant conditions and causes mixtures at the lower end of the temperature range to not ignite. Hence the combination of the constrained reaction volume stage-filling technique, mixture dilution, and novel techniques was used to investigate and interpret the pressure rise phenomenon before ignition.

Presenting Author: Michael Pierro University of Central Florida

Presenting Author Biography: Michael Pierro is a current Aerospace Engineering doctorate student from the University of Central Florida, where he received his Mechanical and Aerospace Engineering bachelor’s degrees in 2020. He performs combustion diagnostic research at the High-Pressure Extended Range Shock Tube for Advanced Research laboratory (HiPER-STAR) under the advisement of Subith Vasu, Ph.D. He is a member of the Center for Advanced Turbomachinery and Energy Research (CATER) and his work investigates next-generation fuel blends for gas turbine engines. He has also performed research on liquid methane (LCH4) oxidation at rocket engine thrust chamber conditions.

Authors:

Michael Pierro University of Central Florida
Justin Urso University of Central Florida
Cory Kinney University of Central Florida
Shubham Kesharwani University of Central Florida
Jonathan Mcgaunn University of Central Florida
Christopher Dennis University of Central Florida
Subith Vasu University of Central Florida