SUMMARY

This research investigates oscillating heat pipes (OHPs) through numerical simulations. The goal of this research is to numerically simulate OHPs and study their application for heat dissipation of high heat fluxes in aerospace applications. OHPs have complex physics and are not easily numerically modeled. This work first analyzed the OHPs with water as working fluid and learnings were used to explore OHPs with liquid metals as working fluids. In this study, finite volume modeling in ANSYS Fluent is used with the Volume of Fluid two-phase model. The Lee Model is chosen for modeling phase change between liquid and vapor. Initial models utilize water and water vapor to validate solver and mesh settings. The initial shape of the OHP is a 2D single loop including solid walls, which are modeled to accurately consider radial and axial heat transfer into account. The boundary conditions are constant flux into the evaporator end, adiabatic condition in the middle, and constant temperature at the condenser end. After validation, liquid metals have been chosen as working fluids due to their demonstrated ability to dissipate high heat fluxes. The boundary conditions for the liquid metal OHP are similar to water based OHPs, but high heat fluxes relevant to the leading edges of high Mach number vehicles is applied in the evaporator region. The effective conductivities of OHPs are estimated and then fed into a simplified solid conduction model of the leading edge to get temperature profiles for a specified aerothermal heat flux pattern. An optimization loop is also developed to determine the impact on design choices. The optimization loop was created in ModelCenter and adds parameterization to ANSYS and MATLAB.

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