上向き傾斜加熱平板まわりの自然対流の流動と伝熱

抄録

Turbulent transition mechanisms and local heat transfer characteristics of the natural convective flows over upward-facing, inclined plates were investigated experimentally. The experiments were performed in the range of modified local Rayleigh numbers from 10⁴ to 8×10¹4 and of inclination angles θ from 0 to 90°. The flow fields over the plate and the surface temperatures of the plate were visualized with dye and liquid crystal thermometry. The results showed that longitudinal vortices play a main role on the turbulent transition over the plates of θ<72°. These vortices appear first in the laminar boundary layer, then, detach from the plate and, finally, become distorted. It is found that the heat transfer is enhanced markedly by the detachment and the distortion of these vortices. The local heat transfer coefficients were measured in the laminar, transitional, and turbulent regions. The results show that the coefficients, in particular, in the turbulent region become identical and independent of inclination angles.