| Limiting free surface temperature rise of molten salt Li2BeF 4 (Flibe) is a fundamental feasibility issue for its use in chamber design. The presence of a convective surface mixing effect due to waviness could greatly reduce the free surface temperature rise. However, the prior lack of experimental data for Flibe liquid walls and simulation limits has not allowed researchers to quantify this effect or the range of its influence.; This dissertation quantifies the surface heat transfer rate and waviness for inclined (a > 1°), wavy, and turbulent (Re > 104) fully developed flows, using water to simulate Flibe. This is accomplished using ultrasonic diagnostics and infrared thermography to gather data on an inclined planar open channel flow at the Flibe Hydrodynamics (FliHy) Facility, and then comparing the experimental data to simulation results. This procedure evaluates the closure parameters for turbulence models, verifies the surface temperature modeling results, statistically quantifies the surface waviness, and isolates the surface heat transfer rate.; Overturning waves are shown to promote convective cycling of surface heat into the bulk flow and to result in lower surface temperatures for a given heat flux. (A dye technique is used to visualize the free surface and shows the existence of the overturning waves.) The experiment investigated free surface heat transfer by isolating the surface turbulent Prandtl number. In the sub-critical regime, Fr < 1, the free surface is smooth and has a low surface heat transfer rate. The data agree with previous research based on Ueda's data and the k-ϵ modeling results. The sub-critical flow is found to have a relatively weak ability to restrict the increase in surface temperature under high heat flux.; Next, the research studies super-critical flows for Fr > 1, where it is shown that the surface heat transfer rate and waviness increase substantially, as indicated by: (1) The surface turbulent Prandtl number significantly decreasing towards its bulk value of 0.7, and (2) a redistribution of the wave spectra to higher frequencies. The probability distribution for the waves exhibits a Gaussian profile, in contrast to the previous findings of Dukler. Finally, an exponential Nusselt number correlation is generated based on free surface waviness intensity. |
