Research
Thermoacoustic Instabilities in Gas Turbine Combustors
Thermoacoustic instabilities arise from the coupling between unsteady heat release and acoustic pressure oscillations in combustion systems, potentially leading to large-amplitude pressure fluctuations and structural damage. In annular gas turbine combustors, these instabilities exhibit complex azimuthal dynamics, including standing, spinning, and mixed acoustic modes. This research focuses on understanding the fundamental mechanisms governing these dynamics through theoretical analysis and reduced-order modeling. Particular emphasis is placed on the effects of nonuniform combustor properties, acoustic coupling between burners, and mean azimuthal flow on mode selection, spinning direction, and nonlinear instability behavior. The goal is to improve the prediction, mitigation, and understanding of thermoacoustic instabilities in practical gas turbine combustors.
Combustion Process in Compression-Ignition Engines
Spray ignition in compression-ignition (CI) engines involves complex interactions among fuel atomization, evaporation, turbulent mixing, and chemical reactions under high-temperature and high-pressure conditions. This research focuses on understanding the ignition characteristics of conventional jet fuels, sustainable aviation fuels (SAFs), and their blends under engine-relevant conditions. Particular emphasis is placed on the effects of fuel properties, ambient thermodynamic conditions, and injection strategies, including pilot-main injection, on ignition delay, flame development, and combustion stability. Advanced optical diagnostics, including high-speed schlieren imaging, OH* chemiluminescence, and planar laser-induced fluorescence (PLIF), are employed to investigate spray evolution, fuel–air mixing, and ignition processes. The goal is to identify the fundamental mechanisms governing spray ignition and develop strategies for reliable and efficient combustion of alternative fuels in CI engines.
Development of Liquid Fuel Small Turbojet Engines
Small-scale liquid-fueled turbojet engines present unique challenges in achieving efficient and stable combustion due to their compact geometry, limited residence time, and high thermal loading. This research focuses on the development and optimization of compact combustion systems for small turbojet engines operating on conventional and alternative jet fuels. Particular emphasis is placed on fuel atomization, fuel–air mixing, flame stabilization, and combustion efficiency under practical operating conditions. Experimental investigations of combustor configurations, including cavity-based flameholding concepts, are conducted to evaluate combustion performance, operational stability, and temperature distribution. The goal is to develop compact, reliable, and fuel-flexible combustion technologies for next-generation small-scale propulsion systems.
Reduced Order Modeling of Rotating Detonation Engines
Rotating detonation engines (RDEs) offer a promising approach to pressure-gain combustion by utilizing continuously propagating detonation waves to achieve high thermodynamic efficiency. However, the complex interactions among detonation waves, reactant injection, and combustion dynamics present significant challenges in understanding and predicting their operational stability. This research focuses on developing reduced-order models to investigate the fundamental mechanisms governing detonation-wave propagation, interactions, and stability in RDEs. Particular emphasis is placed on the effects of reactant mixing, background flow, and flow nonuniformities on wave dynamics, directional selection, and post-collision recovery. By identifying the physical mechanisms that govern detonation-wave survivability and stability limits, this research aims to establish fundamental insights and predictive tools for the design of robust and efficient pressure-gain combustion systems.