Launch vehicles experience extreme acoustic loads during liftoff driven by the interaction of rocket plumes and plume-generated acoustic waves with ground structures. Currently employed predictive capabilities are too dissipative to accurately resolve the propagation of 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 NASA and commercial launch vehicles. This project will develop and deliver breakthrough technologies to drastically improve acoustic loads predictions. An innovative hybrid CFD and Computational Aeroacoustics (CFD/CAA) method will be developed where established RANS/LES modeling will be used for predicting the acoustic generation physics, and a high-order accurate unstructured discontinuous Galerkin (DG) method will be employed to propagate acoustic waves across large distances using ideally suited high-order accurate schemes. This new paradigm enables: (1) Improved fidelity over linear methods; (2) Greatly reduced numerical dissipation and dispersion; and (3) Improved acoustics modeling for attenuation, diffraction, and reflection from complex geometry. A proof-of-concept was developed and successfully demonstrated during Phase I for benchmark applications as well as SLS prototype model launch environments. Phase II will deliver production CFD/CAA predictive capabilities with 4th-order spatial and temporal accuracy for near lossless acoustic propagation throughout the launch environment, which will provide NASA engineers with more than a two-fold increase in the range of resolvable frequencies over current methods.More »
The technology developed under this project will contribute to technology areas identified in multiple NASA Space Technology Area Roadmaps, notably, TA01 Launch Propulsion Systems, and TA13 Ground and Launch Systems Processing. This hybrid CFD/CAA tool will uniquely fill the technology gap at NASA centers in defining lift-off environments for on-going and new launch vehicle designs, and for the analysis of noise suppression techniques. The developed tool will provide greater confidence to NASA acoustics engineers offering accurate, quantitative acoustic loading predictions from first principle CFD/CAA simulations for specific launch vehicle configurations. The tool will also be invaluable to payload system and instrument developers, particularly for one-of-a-kind and experimental optics and telescope systems that are susceptible to acoustic effects during liftoff.
The proposed innovation offers significant advantages over aeroacoustic prediction tools currently available in industry. The hybrid RANS/LES and high-order DG modeling will provide a unique combination of robust multi-physics modeling and high-fidelity acoustic propagation physics. The proposed approach will offer a great technology advantage through its improved accuracy for acoustic propagation and its integration within a single massively parallel unified production framework (Loci). The toolset will be invaluable to current and future commercial launch service providers such as United Launch Alliance, ATK, Boeing, Space-X, Orbital Sciences, and payload system and sensitive instrument developers, particularly for one-of-a-kind DoD, NRO, and NOAA satellites. At the end of the SBIR, this technology will be readily available for analysis of micro-jet and active/passive control systems, conventional and STOVL aircraft jet acoustics, airframe and landing noise, and rotorcraft acoustic loading.
|Organizations Performing Work
|CFD Research Corporation
|Marshall Space Flight Center (MSFC)