Overview
Computational fluid dynamics (CFD) simulations are being used to support the design of NASA’s next-generation space launch vehicles. CFD support includes characterizing aerodynamic performance, providing distributed line loads and pressure signatures on the vehicle for structural analysis, performing stage separation analysis, and predicting the launch environment during the ignition and takeoff.
Project Details
CFD simulations of launch vehicle aerodynamics are conducted over the entire ascent trajectory, including solid rocket booster (SRB) separation. Simulation results are used to predict the aerodynamic performance of different vehicle shape designs. Engineers use the CFD-generated line loads and pressure signatures to assess the structural loads and acoustic environments that the vehicle will encounter during ascent. Databases of the aerodynamic forces and moments during SRB separation are also generated in order to assess the potential for re-contact between the boosters and core stage and ensure a safe separation sequence.
Due to the greater thrust of heavy-lift vehicles, launch environment analyses must be performed to ensure vehicle stability, payload safety, and durability of the launch pad where the exhaust jets impinge. CFD simulations have been performed using the existing pad configuration and a preliminary heavy-lift vehicle design. Analysis includes high-fidelity simulations of ignition overpressure (IOP) and acoustic phenomena. Results from these analyses will be used to help reconfigure the launch pad to reduce the strength of IOP and acoustic pressure levels.
Results and Impact
CFD simulation results have been used during two design analysis cycles of the Space Launch System. Launch environment analyses have contributed to the redesign of the launch pad to support heavy-lift vehicles. CFD simulations are an efficient source of critical design data due to the quick turnaround times and minimal cost to produce results for a large number aerodynamic performance databases and pad configurations.
Role of High-End Computing Resources
The high-end computing resources at the NASA Advanced Supercomputing facility enable fast and efficient turnaround times for CFD simulations of space vehicles and launch environments. The Pleiades supercomputer allows viscous simulation databases with hundreds of cases to be completed in under a week using 200 – 300 cores per simulation. Inviscid databases including more than 3,000 simulations have been completed in as little as two days using a single computing node per simulation.
Unsteady launch environment simulations, which require large computational resources (1,000 cores for a week) to accurately resolve the physics, can only be run on supercomputers such as NASA’s Pleiades. NASA’s hyperwall-2 enables researchers to visualize the results.Cetin Kiris, NASA Ames Research Center
cetin.c.kiris@nasa.gov
