Alleyne awarded NRC research fellowship
Keeping a modern stealth aircraft cool has been a growing challenge for the U.S. Air Force. To eliminate heat emanating from inlets and exhausts, stealth aircrafts dump heat into the onboard fuel, becoming “flying Thermos bottles.” Andrew Alleyne, the Ralph M. and Catherine V. Fisher Professor of Engineering, was recently awarded a National Research Council (NRC) Research Associates Program fellowship to help address these challenges.
Alleyne is a professor in the Department of Mechanical Science and Engineering and associate dean for research in the College of Engineering. He will be collaborating for the 2011-2012 academic year with the Air Force Research Laboratory (AFRL) at Wright Patterson Air Force Base in Dayton, Ohio. The focus of his tenure within the Propulsion Directorate at AFRL will be on advanced thermal management systems for current and future generations of aircraft.
“The goal of this critical research is to be able to manage the thermal loads to which modern aircraft are exposed,” Alleyne said. “These loads are highly transient and come from both internal and external sources. What makes them particularly challenging is their magnitude coupled with their highly transient nature.”
Modern aircraft are designed to minimize their visibility or “signature” to the external environment. Consequently, their surfaces tend to retain thermal energy generated internally as well as absorbing thermal radiation from the sun. This can cause internal system temperatures to rise to elevated levels. These conditions are critical to proper aircraft development because as future designs require more power they also have to manage and release a larger amount of heat. If the heat loads are not managed then the systems stop working.
The analogy drawn by Alleyne: Imagine wearing a snowsuit and running a 10k race in the middle of July in Champaign, Illinois. The internal heat loads will become so large that one will overheat. Alleyne’s goal is to figure out how to manage the function of the body to prevent exhaustion. He already tackled this problem with other types of thermal management systems for ground-based vehicles that experience gradual environmental change, but now he is applying these concepts to aircraft.
Over the last decade Alleyne and his research group developed their own simulation tools that model and analyze the transient nature of cooling and refrigeration systems. This toolset interfaces with available computer software called MATLAB/Simulink. It is able to produce accurate realizations of overall systems performing in changing environmental conditions for different types of systems: commercial refrigeration systems, small buildings, refrigerated cars or trucks and other types of vehicles. Using these tools, he and his students have studied methods to optimize the management of transient thermal loads through decision-making algorithms. By continuously monitoring and adjusting the operation of aircraft thermal management systems they are able to maximize the ability to cope with internal and external heat loads.
One of the biggest challenges to addressing the aircraft thermal system, as opposed to refrigerated trucks and other ground systems is that the environmental conditions and loads change much more rapidly and more severely, Alleyne explained. Aircraft experience drastic temperature changes at different altitudes; internal loads from the power system activate at different times. In response to these environmental changes, the best method for monitoring and modulating the heat loads also changes.
“This research is pretty exciting because the number of variables is greater,” Alleyne said. “It is more complex and the changes the system goes through are more complex both internally and externally than anything we’ve taken on before. Moreover, the stakes are much higher because we are talking about national security.”
The objectives of the Research Associateship programs are to provide postdoctoral and senior scientist and engineers of unusual promise and ability opportunities for research on problems—largely of their own choice that are compatible with the interests of the sponsoring laboratories—and to contribute to the overall efforts of the laboratories. The NRC chooses 350 awards from over 1,000 applicants with about a quarter of these going to senior positions. According to the National Research Council website, since 1954, 13 faculty and four alumni from the University of Illinois at Urbana-Champaign received this honor.