Phononic Subsurfaces and Porous Metasurfaces for the Control of Hypersonic Boundary - Layer Flows
Abstract
Approved for Public ReleaseOperating air vehicles at hypersonic speeds significantly reduces flight times and increases range, reinforcing the U.S.#s long-range rapid response capability for strategic dominance. The intricacies of flow fields around hypersonic hardware are challenging. In particular, the transition of boundary layers (BL) from a laminar to turbulent state in hypersonic flows substantially increases surface heat transfer rates and skin-friction drag. The intense thermal and mechanical loads not only challenge vehicle structural design and material selection but also compromise performance. By bringing together expertise in fluid dynamics, phononic crystals (PnC) and metamaterials, high temperature mechanics and oxidation, additive manufacturing (AM), multi-physics modeling, and hypersonic flow experiments, the proposed research on transition and turbulence control offers the Navy a pivotal edgetailored for a new generation of hypersonic vehicles. The ability to control the transition process#reducing turbulent skin friction and surface temperature#elevates vehicle performance, solidifying U.S. strategic and tactical supremacy. A robust approach to prevent, or significantly delay, transition across a hypersonic vehicle s surface has remained elusive for decades. This capability is currently not available due to the presence of a wide range of complex instability mechanisms providing multiple paths to turbulence that cannot be controlled simultaneously. For example, conventional passive flow-control approaches, e.g., porous surfaces, while successful for suppression of some instability modes, have proven to be incapable of attenuating all modes and presently cannot deal with harsh hypersonic flight conditions. A more contemporary approach based on acoustic metasurfaces is presently plagued by limitation to an extremely narrow frequency regime, which undermines robustness and prohibits practical deployment. The narrow-band limitation also restricts its effective use for controlling turbulence and/or shock-wave BL interaction.The team envisages that a profoundlynew way of approaching this challenge is required. The goal of this MURI project is to establish--using theory, numerical modeling,advanced AM, and experimentation--an understanding and framework for passive manipulation of hypersonic flows with PnC- and metamaterial-based phononic subsurfaces (PSubs) and porous metasurfaces (PM) for the purpose of reliably delaying laminar-to-turbulent transition and controlling turbulence. The team will develop rigorous local and global flow stability theories coupled with novel concepts of PnC- and metamaterial-based PSubs and PMs. The PSubs will be designed to generate elastic waves that coherently interfere withflow instabilities over a broad frequency range, delivering unprecedented passive flow control. An advanced adjoint-based optimization procedure will be developed to further elevate flow control efficacy. AM of complex refractory metal lattices, with oxidation resistant overlay/sacrificial coatings, will be employed to design these innovative materials and extensive thermomechanical characterization will be used to elucidate micromechanical behavior at high temperatures. To form a comprehensive understanding of the performance in various regimes of hypersonic flow conditions, flow experiments will be performed in different types of hypersonic facilities. The proposed research lays the foundation for the emergence of a new class of materials that enables spatially tailored intrinsic passive flow and thermal BL control while withstanding the harsh conditions encountered in hypersonic flight.The proposed MURI team received strong endorsements from government research labs and private industry partners. The team s devotion to collaboration will ensure the research aligns with the DoD s broader objectives through review meetings, workshops, student internships, technology exchange, and ongoing dialogue.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Nov 09, 2024
- Source ID
- N000142412682
Entities
People
- Mahmoud Hussein
Organizations
- Office of Naval Research
- Regents of the University of Colorado
- United States Navy