FOR more than a century, American scientists, engineers, technicians, and business leaders led the world in building the finest airplanes and, later, the most powerful rockets for national security and scientific exploration. More recently, U.S. government agencies have encouraged development of new technologies to drastically lower costs and increase innovations in rocket propulsion. In 2010, NASA’s Space Shuttle was retired, and the past decade has witnessed the emergence of small and aggressive U.S. companies aiming to revolutionize the space-launch industry. These fledgling firms are creating new designs for liquid-fueled engines and reusable, manned launch vehicles that will significantly reduce the costs of putting people and payloads into space.
Laboratory scientists and engineers are demonstrating to many of these companies the power and utility of high-performance computing (HPC) in developing and assessing future technologies. Using computers as a virtual test bed has become a hallmark of Lawrence Livermore research. With HPC machines, scientists and engineers can evaluate new ideas, designs, and materials in silico before prototypes are built and tested. In this way, companies deliver new products into the marketplace more quickly and with less expense.
Lawrence Livermore efforts have now demonstrated the value of HPC in transforming the design and testing of new rocket engines and launch vehicles. Laboratory scientists and engineers have completed two space-technology ventures for the Defense Advanced Research Projects Agency (DARPA) and two ambitious small American companies. For the first project, the Livermore team simulated the performance of a novel liquid-propellant rocket engine intended for DARPA’s Next-Generation Rocket program. The second effort used simulations to study the thermal and structural response of a design for DARPA’s reusable launch vehicle called the XS-1.
These endeavors have demonstrated Livermore’s long-standing ability to quickly assemble teams comprising subject matter experts in a wide range of disciplines such as materials science; combustion chemistry and physics; flight aerodynamics, including thermal and structural stresses; and supercomputing simulation. The most advanced physics-based computational models were brought to bear on these projects to simulate the physical processes associated with liquid-fuel combustion and space-flight dynamics.
Using Livermore’s Cab and Syrah supercomputers, engineers performed three-dimensional (3D) simulations using up to a 60-million-cell mesh on a 10-nanosecond and 10-nanometer scale to produce high-fidelity 3D simulations of a rocket engine in operation. While resolving short-lived temperature and pressure transients that influence the safety and efficiency of engine operation, the simulations provided some of the most detailed views ever of how oxidizer (liquid oxygen) interacts with the turbulent methane fuel. The Livermore team also performed simulations of the engine operating at up to 30,000 meters in altitude. For the launch-vehicle design, the team examined the flightworthiness of the system at various points along a simulated flight trajectory from liftoff to Mach 10 and back to vertical landing. In particular, the team, in collaboration with designers from the companies, studied stresses on the supports for the fuel tank.
Although HPC is an immensely powerful tool, researchers must ensure the physical models accurately represent the way materials behave when subjected to extreme environments. The Laboratory has a number of world-class facilities, such as the National Ignition Facility, High Explosives Applications Facility, and high-pressure laboratories, for conducting subscale experiments to validate advanced physical models.
Lawrence Livermore has a proven track record of helping American companies use HPC for designing and evaluating products to significantly reduce development time and cost. A pressing national need exists for a vigorous, domestic space-launch industry, and Laboratory scientists and engineers are leading the way in using HPC to ensure the industry’s success and the effectiveness of the technologies it delivers.