When the Wright brothers flew their primitive airplane for the first time in 1903, they used an eight-horsepower engine that was able to achieve a top speed of 30 miles per hour. Today, most standard passenger planes average speeds 46 times that of the Wright Flyer, with the fastest manned military plane clocking in at over 4,000 miles per hour.
To achieve these astounding speeds, aircrafts need to have powerful, carefully designed engines. University of Connecticut mechanical engineering assistant professor Xinyu Zhao is working to develop a better understanding of the combustion process that powers aeronautical engines through a $450,000 grant from the U.S. Department of Defense and U.S. Air Force.
Some aeronautical engines and other parts of the propulsion systems have “turbulent premixed flames” composed of a fuel and oxidizer that are mixed by turbulence before they burn up. Combustion is essential to how these engines function, as it is responsible for generating the thrust which propels the plane forward. But “pockets” can form that interfere with the reaction.
These pockets of unburnt gases can form inside burnt gases and burnt gas pockets can also form in unburnt gases. The presence of these pockets complicates the internal structures of the flames. They can accelerate the energy conversion processes, which can in turn lead to enhanced power output or pose a serious problem for the stability of an engine.
By developing a better understanding of the physical impacts of these pockets and the mechanisms leading to their creation and destruction, Zhao and her team will work toward finding conditions to promote or prevent the formation of these pockets, to either maximize or minimize their impact.
“It is an exciting era for combustion research because we have so many experimental and computational tools to scrutinize these flames, owing to the hard work of generations of combustion engineers and scientists, with help from state-of-art supercomputers,” Zhao says. “The findings from this study might inspire new combustion modeling approaches or new experimental designs, which can further accelerate our understanding of combustion at engine relevant conditions.”
Zhao received her Ph.D. in mechanical engineering from Pennsylvania State University in 2013 and went on to work as a postdoctoral fellow in the Combustion Energy Frontier Research Center at Princeton University. She joined UConn’s faculty in 2015. Her research focuses on computational fluid dynamics with a particular interest in high-fidelity simulations of reactive flows, radiative heat transfer, multi-phase combustion, and the interplay of computation and experiments.
This grant is U.S. DOD no. FA9550-18-1-0173.