Selim Elhadj | 20-ERD-027
The study of material response and strength for vehicles in the harsh environment of sustained, trans-atmospheric hypersonic flight (above Mach 5, or 5 times the speed of sound) is challenging because of the need to impose the fully-dependent dynamic conditions, such as unprecedented thermal and mechanical loads, along with boundary layer air-surface reactive chemistry subject to dynamic unsteady flowfields. Although these types of studies are needed, it is expensive and time consuming to carry out even limited materials response studies during flight tests or at ground-based test facilities with large wind tunnels, many of which lack the diagnostic capabilities needed to conduct these types of material characterization studies.
The aim of our research was to explore ways to experimentally replicate the hypersonic environment in order to study material response in this harsh environment. We focused on the initial steps needed to develop a ground-based, laboratory-scale, hypersonic wind tunnel that can probe key physics phenomena inherent to hypersonics. Our work included designing a lab-scale, Mach 3-7 wind tunnel, which can probe damage to test articles. We also developed flow and material diagnostics for this type of hypersonic wind tunnel environment. Key efforts included using hypersonic computational fluid-simulation codes to design facility components, and using three-dimensional printing to produce a Mach 3 nozzle prototype.
Our research drew on Lawrence Livermore National Laboratory's core competency in lasers and optical science and technology by developing advanced, laser-based diagnostics to analyze flow and materials responses in situ. We also built on the Laboratory's core competency in high-performance computing, simulation, and data science, including our work that will help extend simulation and modeling capabilities to the hypersonics regime.
This research supports missions at the DOE and the Department of Defense, including the Defense Advanced Research Projects Agency (DARPA), including missions focused on determining the response of materials used for high-Mach-number flight vehicles exposed to reactive flows and the harsh and hostile environment inherent to sustained trans-atmospheric hypersonic controlled flights. In addition, this research supports NASA missions, including the need to determine re-entry loads to manned spacecraft, spent rockets, or erosion mechanisms to satellites or spacecraft. Our research also supports the Laboratory's nuclear threat reduction mission research challenge.
Publications, Presentations, and Patents
Elhadj, S. 2020. "Local Energy Matter Interactions (EMI) and Materials Response in Hypersonic Environments." Air Force Research Laboratory Materials and Manufacturing Directorate Presentation, September 2020. LLNL-PRES-810291