THERMALLY UNSTABLE CONVECTION WITH APPLICATIONS TO CHEMICAL-VAPOR-DEPOSITION CHANNEL REACTORS

The three dimensional, thermally unstable flow and heat transfer of a gas have been studied in a horizontal channel with applications to che mical vapor deposition (CVD). The cases examined include flows that ex hibit a longitudinal roll instability and a combination of both transv erse, traveling waves and longitudinal rolls. Detailed results are pre sented for two values of the temperature ratio epsilon = (T(l)-T(o))/T (o) = 0.01 and 2.33 (helium), Grashof number Gr = gepsilonH-3/nu(o)2 = 125 000, Prandtl number Pr = nu(o)/alpha(o) = 2/3, aspect ratios L/H = 10 and W/H = 2. For epsilon = 0.01 and Reynolds number Re = uHBAR/nu (o) = 250, longitudinal rolls result whereas for Re = 100 a combinatio n of transverse waves and longitudinal rolls occurs. For epsilon = 2.3 3 and Re = 100 the longitudinal roll instability is present.