September 11, 2014
Kyle Higdon, an aerospace engineering PhD candidate co-advised by Professors David Goldstein and Philip Varghese, was awarded the selective NASA Space Technology Research Fellowship (NSTRF).
Higdon received the grant for his research topic titled “Application of the MCMC Method for the Calibration of DSMC Parameters to NASA EAST Results for Ionizing, Radiating Hypersonic Flows.” This research project focuses on developing computer simulations of hypersonic shock waves that occur when a space vehicle re-enters the Earth’s atmosphere. The simulations provide information about the effect of high temperature particle reaction rates on the simulation of hypersonic shock waves.
“Experimental tests relating to hypersonic shock waves are costly and unreliable,” said Higdon. “My research is directed toward improving predictions and modeling of such waves.”
The fellowship is a training grant given to 54 graduate students from a competitive selection of highly qualified applicants from accredited U.S. universities. It encourages students to create innovative new space technologies for America’s science, exploration and economic future. As part of the fellowship, NASA’s Dr. Derek Liechty will collaborate on the research project with Higdon and his supervisors at UT, and Higdon will spend time at NASA Centers during the summer. The fellowship can be renewed up to three additional years and will cover full tuition and stipend.
A vehicle re-entering the Earth’s atmosphere can fly in excess of 25 times the speed of sound, causing a hypersonic wave to develop in front of the vehicle. This can lead to dangerously high temperatures that could be damaging to the vehicle and space crew.
Higdon’s Direct Simulation Monte Carlo (DSMC) simulations model various molecules, atoms, ions, and electrons that occur in the high temperature gas downstream of a hypersonic shock wave and their interactions with each other. Uncertainty quantification of the model is then performed to find important chemical and ionization reaction rates. Determining the reaction rates that are most relevant can make hypersonic testing more efficient and less costly.
Space vehicles are currently equipped with heat shields to protect them from the extreme temperatures caused by the shock wave, but these shields can be fairly heavy, which require the vehicles to use more fuel.
“With the vehicle structure currently being more conservatively built, an improved understanding of the relevant reaction rates can cut the cost of travel by eliminating material and the amount of fuel used,” said Higdon. “My research is important because it can close the loop between experiments and simulation and assist experimentalists in identifying which reaction rates are critical for future investigation.”
Higdon hopes to make an impact in the DSMC community while also developing connections with NASA during his fellowship. His plans after graduation are unknown, but he would like to continue performing research.
