Variable Gravity Two-Phase Heat Sink for Airborne Directed Energy Systems

Two-phase cooling systems are an enabling technology for high energy lasers deployed on aircraft, but the flow morphology can be influenced by the accelerations of airborne platforms, affecting the thermal and flow performance of the cooler. Microchannel coolers using low Bond number coolants can reduce these effects, since surface tension forces dominate over buoyancy effects. The insensitivity to accelerations was demonstrated in the Phase I program: this Phase II effort will provide the understanding and computational tools required to design two-phase microchannel systems with confidence.The program will study the behavior of two-phase flows in high aspect ratio rectangular microchannels at high heat fluxes, using flow visualization and computational fluid dynamics to create reliable flow maps. The understanding gained from these studies will be used to improve computationally efficient numerical analysis tools, which can be used in future design efforts. Test assemblies will be delivered for high-acceleration centrifugal testing, and two-phase microchannel coolers will be designed, built and tested with laser diodes to demonstrate the performance.