SBIR-STTR Award

Launch vehicles experience extreme acoustic loads dominated by rocket exhaust plume interactions with ground structures during lift-off, which can produce damaging vibro-acoustic loads on the vehicle and payloads if not properly understood and mitigated against. Existing capabilities for modeling the turbulent plume physics during early lift-off are too dissipative to accurately resolve the propagation of acoustic waves throughout the launch environment. Higher fidelity non-dissipative analysis tools are critically needed to design mitigation measures (such as water deluge) and launch pad geometry for current and future launch vehicles. This project will build upon existing capabilities to develop and deliver breakthrough technologies to drastically improve predictions of transient acoustic loading for launch vehicles in motion during early lift-off. Innovative hybrid CFD/CAA techniques based on RANS/LES modeling for acoustic generation physics and an unstructured discontinuous Galerkin method will be employed to model long distance acoustic wave propagation along with vehicle motion using ideally-suited high-order accurate schemes. This new paradigm enables: (1) Greatly reduced dissipation and dispersion; (2) Improved modeling of acoustic interactions with complex geometry; and (3) Automatic identification of transient acoustic environment including vehicle motion. Merits of this approach will be investigated and demonstrated during Phase I. In Phase II, the methodology will be refined and validated against realistic targeted applications.

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.