Research
The Propulsion and Clean Energy Research Group specializes in experimental studies of combustion, multiphase flows, and propulsion systems. We use a range of optical techniques, including line-of-sight attenuation, spectral soot emission, laser-induced incandescence, Mie scattering, and particle image velocimetry. Our laboratory also supports instrument development in-house, with machining, 3D printing, digital mass flow control, PID temperature control, flow calibration, and motorized motion control.
Soot Formation at Atmospheric and High Pressure
Soot, known as particulate matter in the automotive industry and black carbon in the atmospheric sciences, forms in the flames of hydrocarbon and alternative fuels. Its emissions affect both human health and climate, and they are increasingly regulated.
Fine particulate matter, generated largely by combustion, is a leading cause of air-pollution deaths worldwide. Black carbon is also among the largest contributors to warming after carbon dioxide. Unlike carbon dioxide, soot remains in the atmosphere for only weeks, so reducing soot emissions slows warming almost immediately and improves air quality at the same time.
We study soot formation in laminar flames from atmospheric pressure up to 35 bar in our high-pressure combustion facility. We measure soot concentration, temperature, and soot maturity with optical diagnostics such as LOSA, SSE, and LII. We collect particles by thermophoretic sampling for electron microscopy. We also study how the same flames can produce useful carbon nanomaterials, such as fluorescent carbon dots.
Alternative Fuels
Aviation and power generation are moving toward lower-carbon fuels, including sustainable aviation fuels, hydrogen, and ammonia. These fuels are often blended with conventional hydrocarbons and burned at high pressure in gas turbines and engines. Gas turbine design is tightly constrained by safety and certification requirements, so new fuels must be understood before they are widely adopted. How these fuels and blends change flame structure and soot formation, especially at engine-relevant pressures, is still uncertain. We study the combustion properties of alternative fuels, such as flame stability, temperature, and sooting propensity, and compare them with those of conventional fuels. The goal is knowledge that helps engineers design clean, fuel-flexible combustors.
Hybrid-Electric Propulsion
Aviation accounts for about 2 to 3% of global carbon dioxide emissions, and its share is growing as air traffic increases. Fully electric aircraft would eliminate in-flight emissions, but current batteries store about 50 times less energy per kilogram than jet fuel. For most missions, the batteries would be too large and heavy. Hybrid-electric systems combine a fuel-burning engine with electric power and can recharge their batteries using excess power from the engine.
Hybrid-electric propulsion aims to reduce fuel burn, emissions, and noise. Because the technology is at an early stage in aviation, its performance must be carefully evaluated and improved. We model and test ground-based hybrid-electric systems to assess their feasibility and improve their performance.
