NUMERICAL SIMULATIONS OF TURBULENT NATURAL CONVECTION IN LATERALLY-HEATED CYLINDRICAL ENCLOSURES WITH BAFFLES FOR CRYSTAL GROWTH

摘要

Ammonothermal crystal growth technique is one of the most effective methods used for growing Gallium Nitride (GaN) crystals. GaN crystals have wide applications in light emitting diodes (LEDs) or UV lasers. Three-dimensional large eddy simulations (LES) of natural convection in a laterally heated cylindrical reactor, using the commercial computational fluid dynamics (CFD) software ANSYS FLUENT, are presented for a Rayleigh number of Ra=8.8 ×10~6. The objective of the current calculations is to understand the effect(s) of opening area of the baffle on the flow pattern and temperature distribution inside the reactor. The baffles considered in this study are annular hollow discs with different opening areas. Three cases with total opening areas of 40%, 25% and 100% (baffle-less) are considered. Velocity and temperature distributions across the different planes and lines, are analyzed in order to obtain information on the flow and heat transfer processes (temperature maps) resulting from various baffle openings.