Additively Manufactured Oscillating Heat Pipe for High Performance Cooling in High Temperature Applications

The advent of additive manufacturing makes available new and innovative integrated thermal management systems, including integrating an oscillating Heat Pipe (OHP) into the leading edge of a hypersonic vehicle for rapid dissipation of large quantities of heat. OHPs have interconnected capillary channels filled with a working fluid that forms a train of liquid plugs and vapor bubbles to facilitate rapid heat transfer. Multiple additive manufacturing techniques may be used, including powder bed fusion, binder jetting, metal material extrusion, directed energy deposit, sheet lamination, ultrasonic, and electrochemical techniques. These high performance OHPs can be made with materials such as Refractory High Entropy Alloys (RHEAs) that can withstand high temperature applications. The structure of the OHP can be integrated into the constructed leading edge. The benefits include a heat transport capacity of 10 to 100 times greater than before. Integrated OHPs avoid the bends or welds in traditional heat pipes, especially at the locations where the highest thermal stresses might cause thermal-structural failure of a leading edge. Alternating the diameters of the OHP channels alleviate start-up issues typically found in liquid metal oscillating heat pipe designs in high temperature applications by aiding in the instigation of a circulating flow due to multiple forces acting upon the working fluid. High performance cooling techniques for enhanced heat transfer for high temperature applications are increasingly important, particularly in the field of aerospace engineering. For example, leading edges of wings on hypersonic vehicles may reach upwards of 2000 C, and such heat quickly degrades the leading edge. Conventional heat pipes contain bends or welds in the material that can compromise the structural integrity of the wing leading edge. Oscillating Heat Pipes (OHPs) are a newer form of heat pipe which can cool more efficiently than traditional heat pipes, and are easier to manufacture. NASA Ames Research Center has developed a novel additive manufacturing technique to manufacture OHPs from Refractory High Entropy Alloys (RHEAs). These OHPs are effective in hypersonic vehicles with sharp, shape-stable wing leading edges. Additive manufacturing allows for enhancements such as alternating-diameter channels, allowing for changes in pressure.