Jackson Brings Rocket Knowledge to AE

2012-10-03

Dr. Thomas L. Jackson’s connection within the Aerospace Engineering Department at Illinois became even closer this fall with his new appointment as a Research Professor.

Dr. Thomas L. Jackson
Dr. Thomas L. Jackson

Previously an adjunct professor, Jackson has taught courses within AE for the past five years, and has long collaborated with AE faculty and graduate students on research efforts.

Professor Jackson came to the Urbana campus in January 1988 as the first scientist hired for the UI Center for Simulation of Advanced Rockets (CSAR). The U.S. Department of Energy funded CSAR to accurately predict through computational simulation the performance, reliability, and safety of solid rocket motors. At that time DOE was considering simulation solutions for nuclear stockpiling, and the complexity of simulating the physics of rockets offered an example for how to go about it.

Jackson was responsible for investigating the propellant’s microstructure, examining issues such as burning rate, pressure response, erosive burning and aluminum particulate burning. Throughout CSAR’s thirteen years, Jackson and his colleagues developed several very complicated computer codes modeling the rockets’ propellant behavior. With the knowledge gained from CSAR, Jackson and his UI colleagues William Dick, Mark Brandyberry and Fady Najjar formed their own company, IllinoisRocstarLLC, located in the University of Illinois Research Park. 

Typical microstructure generated by Rocpack.
Typical microstructure generated by Rocpack.
Numerical simulation of solid propellant combustion.
Numerical simulation of solid propellant combustion.

IllinoisRocstar has contracts with the University of Illinois, Purdue University and Notre Dame University; grants from government agencies including the Department of Energy (DOE), the National Aeronautics and Space Administration (NASA), Sandia National Laboratories, the Army, the Navy, the Air Force, and the Missile Defense Agency; and work with industries including ATK, a prime supplier of aerospace and defense products.

Starting with a focus on solid rocket propellants, IllinoisRocstar has expanded into energetic materials and other areas, and now has five full-time employees, 12 part-time employees, and several faculty consultants, Jackson said.  “Companies want us to analyze what’s going on in their products, refine what they’re doing and provide support and analysis,” he said. “As you understand what’s going on, you have better ability to make refinements.”

Understanding the dynamics and coupling between the propellant and what goes on inside a rocket are key to assuring the safety, reliability and performance of the motor.

Solid propellants consist of a combination of fuel and oxidizer. Unlike air-breathing aircraft, which take in oxygen from the atmosphere, rockets must carry their own oxygen supply for burning as there is none in space. Jackson said the two ingredients are combined in what is similar to a mixing bowl, then poured into molds of various shapes and cured to become solid.

The best way to generate the microstructure of these packs is in a simulation, he said. Rocpack, one of the several specialized codes developed by Jackson for solid propellants, can also be used to simulate packs used for emulsion, rocks, concrete, and explosive studies.

In some current work, Rocpack is used to simulate energetic (explosive) crystals as they grow in size and number, and Jackson and his colleagues observe how they burn at their surface. “In our simulations we get a reasonably close approximation of the simulated burn to the actual burn – within 10 to 15 percent,” he said. “It gives us a lot of confidence that what we’re doing is good.”

Temperature showing hot spot formation due to shock interaction in a heterogeneous explosive. The formation of hot spots can lead to a transition to detonation.
Temperature showing hot spot formation due to shock interaction in a heterogeneous explosive. The formation of hot spots can lead to a transition to detonation.
Numerical Schlieren showing hot spot formation due to shock interaction in a heterogeneous explosive. The formation of hot spots can lead to a transition to detonation.
Numerical Schlieren showing hot spot formation due to shock interaction in a heterogeneous explosive. The formation of hot spots can lead to a transition to detonation.

Knowing a propellant’s microstructure is helpful in designing the propellant for specific launch missions. For example, he said, aluminum particles may be added to the propellant, since the metal increases the chamber temperature and can produce a larger thrust compared to non-aluminized propellants. Unfortunately the aluminum also produces a visible plume from a rocket nozzle, so aluminum should not be added if stealth is desired.

As well as bringing his knowledge to AE, teaching courses on propulsion, solid rockets and a graduate course in boundary layer theory, over the past seven years Jackson has served as associate editor for the American Institute of Aeronautics and Astronautics flagship journal, AIAA Journal. He also is technical chair for the Propellant & Combustion Section of the AIAA/ASME/SAE/ASEE Joint Propulsion Conference scheduled for Summer 2013.