Description: Requirements of next generation commercial Low Earth Orbit (LEO) and Department of Defense DOD hypersonic vehicles, dictate the need for robust thermal management solutions. Managing the heating of a hypersonic wing leading edge can be accomplished through ablation, active cooling, or passive cooling. Passive cooling systems, unlike ablation or active cooling do not dissipate the heat directly but transfer it to where it can be dissipated through convection. Passive cooling systems for hypersonic wing leading edge (WLE) applications have been studied since 1958, but have rarely flown due to manufacturing complexity, thermal stresses, and material compatibility issues. Because of these issues, the current SOA in hypersonic wing leading edges is carbon-carbon which manages heating through ablation. The downfall of an ablative WLE is the shape change that occurs during operation reducing the capability of the vehicle. Furthermore, carbon-carbon (C-C) is expensive and takes a significant amount of time to manufacture. The advent of additive manufacturing makes available new and innovative integrated thermal management systems that were previously not possible. One such system, is a hypersonic wing leading edge with oscillating heat pipes embedded in the thin skin. This new and innovative approach to the thermal management of hypersonic WLE's provides a shape stable design with improved performance over the current state of the art. Furthermore, it eliminates or reduces many of the challenges associated with previous passive cooling concepts through design simplifications. OHPACA is developing extremely efficient thermal management solutions capable of transporting higher heat fluxes than traditional wicked heat pipes while operating under high g-load environments. These systems are integrally manufactured avoiding Coefficient of Thermal Expansion (CTE) mismatch with traditional wicking structures, and have redundant small channels increasing reliability and are compatible with sharp shape-stable leading edges. These systems are applicable solutions for wing leading edges, engine components, and other NASA thermal management needs. Successful development of OHPACA technology will expand the viability of using AM processes and OHP technology for diverse application in commercial space sector high temperature waste recovery, heat exchangers, and other thermal management systems. More specifically, the performance validation testing will have significant impact in opening new markets, lowering price, increasing choice, or providing entirely new capabilities for thermal management.

Benefits: High temperature thermal management systems are a potentially disruptive technology to a wide range of NASA applications such as hypersonic Wing Leading Edges (WLE’s),solar probes, Nuclear Thermal Propulsion (NTP), Plasma-Facing Components (PFC’S) in fusion devices, and engine components. Oscillating Heat Pipes (OHP's) offer many advantages over traditional wick, or capillary driven heat pipes. Advantages include a small channel size, which is compatible with sharp shape-stable wing leading edge geometries, and other applications with volume constraints. OHP's are capable of transporting higher heat flux than traditional wicked heat pipes, while simultaneously operating under high g-load environments. The serpentine channels are integrally manufactured in the structural material, avoiding CTE mismatch with the wicking structure, which simplifies fabrication. Lastly, the passive operation of heat pipes minimizes complexity of other active cooling systems, which increases reliability. When coupled with additive manufacturing, the system offers an affordable fabrication approach to develop OHP-based integrated thermal management systems. Improved 3D printing of tailored refractory metals/alloys has many applications, including electronics; high temperature waste recovery; thermal management systems; and robust leading edges for both commercial LEO and DOD reusable hypersonic vehicles.