University of Wisconsin–Madison engineers are leading research to pave the way for hybrid-electric engines that power uncrewed aircraft systems.
“While there has been a lot of work done on developing hybrid-electric engines for ground vehicles, like the Toyota Prius and many others, there hasn’t been much research on using hybrid engine systems in aircraft,” says David Rothamer, a mechanical engineering professor at UW–Madison and principal investigator of the multi-institutional team supported by $11.4 million from the U.S. Army Combat Capabilities Development Command’s Army Research Laboratory. “So as part of this project, we’ll work on optimizing hybrid systems for aircraft.”
A focus of the project will be to investigate ways hybrid aircraft systems can run reliably and stably on different types of fuel and in extreme environments.
To conduct missions, the U.S. military needs to transport jet fuel to locations around the world, which is expensive and logistically challenging, especially in conflict zones. Having the ability to run an aircraft on whatever type of fuel is readily available locally — be it diesel, jet fuel, gasoline or even ethanol — would greatly ease the Army’s fuel logistics burden.
Compression ignition engines, which are well suited for aircraft systems without crews on-board, require fuel that ignites easily for combustion to occur. However, lower ignition quality fuels such as gasoline, ethanol and even jet fuels made from renewable sources don’t easily ignite in compression ignition engines. They’ll need some help to start the combustion process.
To solve this challenge, the team will study a combustion technique called energy-assisted compression ignition, which shows promise for giving those fuels a boost and thus enabling multi-fuel capability.
“With these low-quality fuels, when the fuel is injected, it’s not going to burn,” Rothamer says. “So we’ll need to assist that ignition process by bringing in some additional energy. The team is investigating the most effective and efficient method of introducing that energy.”
In addition, the researchers will analyze the benefits and tradeoffs involved with adding electric technologies to the propulsion system. For example, integrating electric machines could open up new capabilities — such as electrically assisted turbocharging — but they also require energy storage and additional components, which add weight and complexity to the system.
Read More at https://news.wisc.edu/11-4m-army-grant-supports-aircraft-hybrid-electric-engine-research-at-uw-madison/