Transient Acoustic Environment Prediction Tool for Launch Vehicles in Motion During Early Lift-Off

Launch vehicles experience extreme acoustic loads dominated by rocket plume interactions with ground structures during liftoff, which can produce damaging vibro-acoustic loads on the vehicle and payloads if not properly understood and mitigated against. Existing capabilities for modeling turbulent plume physics are too dissipative to accurately resolve the acoustic propagation and detailed vehicle aft-end acoustics relevant to hydrogen pop deflagration and geometric attenuation. Higher fidelity analysis tools are critically needed to design mitigation measures (e.g. water deluge) and ground structures for current and future launch vehicles, and to accurately predict geometric attenuation which may allow significant reductions in SRB nozzle throat plug material density requirements. This project will significantly advance existing capabilities to develop breakthrough technologies to drastically improve transient acoustic loading predictions for launch vehicles in motion during liftoff. Innovative CFD/CAA techniques will be developed with RANS/LES modeling for acoustic generation and discontinuous Galerkin modeling for acoustic propagation and vehicle motion using ideally-suited high-order schemes. This technology enables: greatly reduced dissipation/dispersion; improved modeling of acoustic interactions with complex geometry; and automatic identification of transient acoustic environment including vehicle motion. A proof-of-concept was successfully demonstrated during Phase I for benchmark applications and SLS prototype launch environments. Phase II will deliver production transient CFD/CAA capabilities for launch vehicles in motion during liftoff with 4th-order accuracy for near-lossless acoustic modeling of near-field geometric attenuation and long-distance propagation, which will provide NASA with dramatic increases in the range of resolvable frequencies over current methods.