Northwestern engineers power futuristic propulsion

Northwestern engineers are among those fueling the future of propulsion, developing next-generation technologies for unmanned aircraft systems that are vital for national security.

Jian Cao, mechanical engineering, in her research space with PhD students Jennifer Bennett (left) and Samantha Webster. Photo: Eileen Molony

A new $3 million award from the U.S. Army Combat Capabilities Development Command's (CCDC) Army Research Laboratory (ARL) will fund the work of five investigators affiliated with the Northwestern Initiative for Manufacturing Science and Innovation (NIMSI), one of the University Research Institutes and Centers that harness interdisciplinary expertise from across Northwestern. The two-year project is part of the Army's Future Vertical Lift (FVL) modernization priority for creating Unmanned Aircraft Systems (UAS) propulsion systems with improved performance and reliability.

Northwestern is contributing its world-class materials science and manufacturing leadership to the multi-institutional effort to develop technologies that could allow the Army's unmanned vehicles to operate on many kinds of fuel and to stay longer in the air, but reliably. "Such a breakthrough is important for the US military, since it could increase performance and reliability while lowering manufacturing costs and increasing resilience," said Jian Cao, NIMSI director and the Cardiss Collins Professor of Mechanical Engineering at the McCormick School of Engineering.

Next-generation propulsion systems must have improved performance, reliability, efficiency, power density, resilience and service life. These outcomes depend on advances in materials and processes related to component resilience, weight and thermal management. "This project looks to provide integrated materials, interfaces and manufacturing solutions, as well as develop human capital capabilities, to address the Army's highest priorities for technologies that can be used in complex environments," said Cao.

Unmanned aircraft systems play a major role in the today's environment, and their role is expected to increase significantly in coming years, especially to effectively support the Multi-Domain Operation in contested environments. "The unmanned aircraft systems provide intelligence, surveillance, reconnaissance, communication, and defensive and offensive services. As such, they often must operate in harsh, disparate and contested environments ranging from high-altitude and low-temperature conditions to runway-independent take-off and landing in various rough terrain, including metropolitan, mountainous, forest, desert and marine settings. As part of its strategy to successfully deploy these unmanned systems," said Dr. Mike Kweon, program manager for the lab's Versatile Tactical Power and Propulsion Essential Research Program. "The Army needs innovative unmanned aircraft systems, and propulsion systems are critical to move them faster and further but reliably at all operating conditions including fuels and environment. Current UASs suffer from inadequate performance, suboptimal reliability and increased life-cycle costs. That's because they use propulsion systems that have been designed for civilian ground applications, rather than the harsh conditions of military operating environments."

The Northwestern research project at NIMSI is part of that broader strategy. The research team, in addition to Cao, includes McCormick School faculty Yip-Wah Chung, David Dunand (both materials sciences and engineering), Gregory Wagner and Q. Jane Wang (both mechanical engineering). Cao says that Northwestern is well-positioned to work with the Army on this groundbreaking focus area due to the University's long-established excellence in material design, surface interaction (tribology) and catalysis, manufacturing, and computational mechanics.

Over the next two years, the researchers will pursue two main research thrusts: one will address issues of friction and wear at critical interfaces in high-pressure fuel pumps currently used in UAS. The Northwestern team has already run simulations to reveal specific root causes of higher friction that results in piston misalignment and eccentricity, and ultimately mechanical failure; the other thrust will develop high-performance, high-temperature aluminum alloys and additive manufacturing processes to create lighter-weight materials for use in propulsion systems. Their research will leverage advances in efficient computational material design methods, multiscale computational approaches, coating methods and innovative hybrid rapid manufacturing processes.

The project also will include prototyping of lightweight materials and their manufacturing process methods. The Northwestern engineers will work with four industry partners: Valvoline (surface engineering), ECK Industries (casting), NanoAl (alloy development), and DMG-MORI (additive manufacturing), for furthering commercialization and implementation efforts for the Army's use.

"This project highlights Northwestern's great strengths in engineering and materials science," said Vice President for Research Milan Mrksich. "It also showcases the important ways that our University Research Institutes and Centers catalyze interdisciplinary science by bridging different departments across Northwestern, while also collaborating with industry to translate foundational breakthroughs into important applied innovation."

This new collaboration between Northwestern and ARL is stimulated by the establishment of ARL Central, part of ARL's Open Campus model, and the Center for UAS Propulsion (CUP).

ARL Central Regional Lead Dr. Mark Tschopp stated: "Collaborative research partnerships between the Army, academia and industry are crucial to achieving our mission. Northwestern University is bringing subject matter experts, unique facilities and great students with diverse background in a partnership with the Army to advance these technologies and provide future capabilities for the warfighter."

Other Army collaborators include the University of Illinois at Urbana–Champaign, the University of Illinois Chicago, the University of Wisconsin-Madison, and University of North Texas.

"Northwestern is pleased to be part of a strong consortium of universities working to address the near-term needs of the military and on innovations that will in the long term benefit the civilian sector, especially in our Midwest region," said Northwestern Special Assistant to the President and Director for Government Relations Bruce Layton.

By Matt Golosinski