In catalytic combustion, reactions occur on the surface of the catalysts. It is possible to achieve ultra-low NOx emission (< 1 ppm) and highly stable combustion. We have investigated catalytic combustion of syngas (CO+H2 mixtures) and methane (CH4) at various fuel-to-air ratios. 

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Have you ever wondered how the flames inside an airplane engine stay steady, even at high speeds? One common technique is called "swirl," where the fuel and air are spun into a vortex, creating a small recirculating zone that helps keep the flame stable. During my PhD, we explored a similar type of flows — but with a twist. Instead of spinning the air and fuel in one direction, we tried spinning these in opposite directions, a setup known as "counter-swirl," which isn’t usually used in airplane engines. This created some fascinating and unusual flame patterns that we studied in detail. 

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The swirl flames are unique as they exhibit different kinds of periodic motions. In our study, we observed a coexistence of global fluctuation and precession motion. Global fluctuation shows a fluctuation that spans the entire combustor. Whereas, the precession motion shows a spinning motion of heat-release fluctuations around the combustor axis. We studied how these two periodic modes change with different flow conditions. See our detailed study here.  

In gas turbines and combustors, swirling flows are utilized as it improves combustion stability and operating range because of the recirculation zone. The formation of a recirculation zone is often termed as vortex breakdown. Understanding and predicting this breakdown is still extremely difficult. We added complexity by introducing an additional stream and observed the change in vortex breakdown mode. We are currently studying this transition and the physics behind it. Please click here to know about the experimental findings. 

A new technology, Flash reduction, can convert micron-sized iron oxide to iron in seconds. The major challenge of this technique is to generate high temperatures. We proposed to utilize hydrogen flames to generate high temperatures in our theoretical study. However, the hydrogen-air ratio and inlet temperature of the flame play a big role in determining the reduction degree. Please check here to know about the theoretical study.