摘要 : This study presents the effect of openings on the ventilation rate of an experimental proposed octagonal greenhouse in a transient flow. Furthermore, it makes a comparison between the free ventilation of the proposed greenhouse wi... 展开 This study presents the effect of openings on the ventilation rate of an experimental proposed octagonal greenhouse in a transient flow. Furthermore, it makes a comparison between the free ventilation of the proposed greenhouse with an Arc greenhouse with two-dimensional computational fluid dynamic simulation. To simulate airflow in the Arc greenhouse, we selected a one-side roof vent openings, butterfly-type side vent openings and one-side-face to face-roof vent openings as opening designs. Moreover, two octagonal greenhouse portions were selected due to changes in cross-sectional area. The results showed that the average wind speed in the greenhouse equipped with butterfly-type side vent opening was higher than other greenhouses, but the temperature of air inlet was distributed less slowly. To illustrate the accuracy, the computational fluid dynamic results, which include wind speed and temperature, were compared with the measured values from the proposed octagonal greenhouse. Moreover, this study investigates the effect of greenhouse shape and openings on turbulence formation and the effect of turbulence on greenhouse climate. After 10 min of simulation, the average total temperature in the greenhouses with butterfly-type side vent openings and one-side-face to face-roof vent openings models had still not reached the outside air temperature. Based on observations, like the average total temperature, the average total airflow velocity was also close in both sides of the octagonal greenhouse. The simulation results show that the speed of free ventilation and temperature distribution in the proposed octagonal greenhouse were higher than the Arc greenhouse with other openings design. 收起