Effect of Vent Area Ratio on Vent Flow Characteristics and Temperature D istribution in a C ompartment F ire with T wo Ceiling Vents

Abstract

In this study, the effect of the vent area ratio on vent flow characteristics and temperature distribution in a compartment during a fire in the compartment with two ceiling vents was examined. The area ratio (A<sub>1</sub>/A<sub>2</sub>) between ceiling vent 1 (CV1), with a duct height of 0.19 m, and ceiling vent 2 (CV2), with a duct height of 0.05 m, was varied from 0.052 to 0.542, 1, 5.587, and 19.36, and numerical simulation was performed under these conditions. As the A<sub>1</sub>/A<sub>2</sub> ratio increased, the flow pattern changed from unidirectional inflow to bidirectional flow for CV1 and from bidirectional flow to unidirectional inflow for CV2. When the A<sub>1</sub>/A<sub>2</sub> ratio was 0.542, the outflow and inflow mass flow rates for CV1 and CV2 were found to be nearly equal. The outflow and inflow mass flow rates at CV1 were higher than those at CV2 when the A<sub>1</sub>/A<sub>2</sub> ratio was high, while the outflow and inflow mass flow rates at CV2 were higher than those at CV1 when the A<sub>1</sub>/A<sub>2</sub> ratio was low. Furthermore, it was observed that the temperature was lower and the temperature difference between the higher and lower regions in the upper part of the measurement position decreased near the lower part of the vent with a larger area compared to the vent with a smaller area. This was probably because the mixing effect increased near the vent with a larger area due to the occurrence of the active bidirectional flow pattern. When the flow pattern at CV1 was bidirectional, the previous correlation for predicting mass flow rate was examined. It was found that the previous correlation underestimated the mass flow rate of the numerical simulation conducted in this study.

Effect of Compartment Height with Fire Source on Horizontal Vent Flow and Temperature Distribution

“…. Li (7) (11,12) 가 일부 수행되었다 과 . Park Lee (11) 본 연구에서는 기존에 Park (13) 이 수행한 연구를 토대로, Park (13) 의 구획실과 바닥 면적은 동일하지만 구획실의 높이는 배 높은 수평 개구부가 설치된 구획실을 대상으로 전산시뮬 5 레이션을 수행하였다 본 전산시뮬레이션과 .…”

Comparative Study of Numerical Simulation and Experiment on Temperature Distribution and Central Vent Flow Velocity in Ceiling-vented Compartment Fire

“…In the presence of two ceiling vents, bidirectional flow or unidirectional inflow was observed at each vent, and the flow combination was determined by the vent conditions. Considering the previous studies [1][2][3][4][5], it was reported that a fire in a compartment with a ceiling vent led to a very complex vent flow, which had a significant impact on the fire phenomena in the compartment. Additionally, in the previous studies [1][2][3][4][5], numerical simulations were conducted using the fire dynamics simulator (FDS).…”

“…This aids in understanding and predicting the compartment fire phenomena and in designing buildings to reduce human and property damage.On the other hand, research on compartments with ceiling vents is applicable in atriums, theater, and ships [1]. Some studies on fire phenomena in compartments with ceiling vents have been reported [1][2][3][4][5]. Zhang et al[1] conducted a numerical simulation on the effects of ceiling vent location (center and corner) on smoke filling process, oxygen concentration, gas temperature, and vent flow characteristics (pressure, velocity, and mass flow rate) in a compartment fire with a natural ceiling vent.…”

“…On the other hand, research on compartments with ceiling vents is applicable in atriums, theater, and ships [1]. Some studies on fire phenomena in compartments with ceiling vents have been reported [1][2][3][4][5]. Zhang et al…”

“…Park and Lee [4] examined the effects of the duct height of two ceiling vents and the location of the fire source on the vent flow pattern, mass flow rate, and temperature distribution in the compartment. Subsequently, Park and Lee [5] measured the flow pattern and mass flow rate through the vent with the area ratio of the two ceiling vents and analyzed the relationship between the vent flow and temperature distribution in the compartment. In the presence of two ceiling vents, bidirectional flow or unidirectional inflow was observed at each vent, and the flow combination was determined by the vent conditions.…”