Wind Effect on Combined Convection and Surface Radiation Heat Losses of a Fully Open Cylindrical Cavity With Insulation

Abstract

Wind effect, of both the wind incidence angle and the wind speed, on convection and surface radiation heat losses of a fully open cylindrical cavity with constant bottom wall temperature was numerically investigated. The impacts of cavity tilt angle and wall temperature were also considered. Temperature contours, velocity contours, and vectors inside and around the cavity were presented. The variations of average convection and radiation heat loss Nusselt numbers Nuc and Nur and percentages of heat losses with related parameters (wind speed, wind incidence angle, tilt angle, and bottom wall temperature) were also shown. In the end, correlations about Nuc and Nur for practical applications were proposed. Results show that compared with no-wind condition, Nuc under a wind condition is almost always higher except for head-on wind with velocity of 1.5 m/s, while Nur is always lower. Nuc varies slightly, while Nur increases rapidly as the bottom wall temperature increases. With the existence of wind, the effect of tilt angle on heat transfer becomes more complex. A critical wind direction close to 30° is detected, which maximizes Nuc and percentage of convective heat loss. The results also demonstrate that wind speed, wind incidence angle, and tilt angle should be considered simultaneously when analyzing heat transfer inside the cavity under a wind condition.