上向き加熱傾斜平板上の強制-自然共存対流の流動と伝熱

概要

論文の詳細を見る
Experimental investigations have been carried out for both aiding and opposing mixed convective flows of air induced over upward-facing, inclined plates heated with uniform heat flux. The tilt angle of the test plate θ was varied from -30° to +30° from horizontal. The experiments covered the ranges of Reynolds and modified Rayleigh numbers based on the plate length as; ReL=2.0x103-2.0x104, RaL*=5x108 -8x1010 for aiding flows of θ≧0°, and as; ReL=1.2x103-104, RaL*=1.3x108-5.0x109 for opposing flows of θ<0°. The flows over plates were visualized with smoke. The results showed that a vortex and a wave type instability of flows occurs over the plate of θ≧0° and θ<0°, respectively. The onsets of the former and latter instabilities are well predicted with the parameter (Grx*/Rex1.8) and (Grx*/Rex2.5), respectively. Local heat transfer coefficients from the inclined plates were also measured. The aiding flows showed higher coefficients than those of the forced convection, while the lower coefficients were obtained near the separation points of the opposing flows. Non-dimensional parameters that describe the heat transfer of aiding and opposing flows were also discussed.