摘要
为分析城市隧道采用顶部壁龛式通风对通风效率的影响,基于ICEM和Fluent软件建立了壁龛角度变化范围在0°~40°的壁龛式纵向通风模型,并进行了数值模拟分析。结果表明:当城市隧道内设置壁龛时,在风机下方出现更低的速度,并在壁龛段出现压力先骤升后骤降的现象,产生负压区,且负压随角度增大而增大,该低速区和负压区均会降低隧道通风效率;同时当壁龛角度由0°增加至40°时,升压系数由0.85降至0.5,降幅达43.75%,通风效率明显降低。建议在满足施工安全及经济性的前提下,壁龛夹角可取最小值,但综合考虑夹角减小产生的漩涡区对通风效率的影响,夹角不宜小于15°。
To solve the problem of insufficient installation space for fans caused by tunnel structure clearance when the urban tunnels adopt the full jet longitudinal ventilation,many urban tunnels adopt the niche jet ventilation.Since the formation of the niche requires the partial enlargement of the cross-section of the tunnel,the angle inevitably directly affects the structure size of the niche and then affects the fan jet efficiency.To study the influence of niche angle on fan efficiency,a series of physical models that change the angle of the niche from 0°(without niche)to 40°are established by using ICEM and Fluent software.The distribution of velocity field,pressure field,and the change of pressure rise coefficient of jet fan are analyzed under different niche angles to optimize the niche design angle and maximize the ventilation efficiency.The results show that when the niches are set in the urban tunnel,not only the lower speed value appears under the fan,but also the pressure rises first and then drops suddenly in the niches,resulting in a negative pressure area.Meanwhile,the negative pressure value increases with the increase of the angle.Both the low-speed and the negative pressure area prevent the longitudinal flow of gas and reduce the ventilation efficiency.As the angle of the niche changes from 0°to 40°,the pressure rise coefficient decreases from 0.85 to 0.5,with a decrease of 43.75%.The ventilation efficiency decreases significantly.However,the pressure rise coefficient of the fan remains above 0.7 as the angle of the niche increases to 20°.It is suggested that the minimum angle of niches should be taken on the premise of meeting the construction safety and economy.Considering the influence of the vortex area caused by the decrease of the angle on the ventilation efficiency,the angle should not be less than 15°.
作者
彭安琪
梁印
李志远
秦文龙
杨斌
PENG An-qi;LIANG Yin;LI Zhi-yuan;QIN Wen-long;YANG Bin(Nanjing Public Engineering Construction Center,Nanjing 210019,China;JSTI Group Co.,Ltd.,Nanjing 210019,China)
出处
《安全与环境学报》
CAS
CSCD
北大核心
2022年第6期3058-3065,共8页
Journal of Safety and Environment
关键词
安全工程
城市隧道
壁龛式通风
壁龛角度
通风效率
safety engineering
urban tunnel
niche ventilation
niche angle
ventilation efficiency
