隧道分岔形式对分流局部通风阻力特性的影响

Influence of tunnel bifurcation form on the local ventilation resistance characteristics of dividing flow

目的:随着城市建设水平和强度提高,带匝道的分岔隧道日趋增多。针对分岔隧道通风设计难题,亟待获取隧道分岔形式对分流局部通风阻力特性的影响规律。方法:通过搭建同步满足阻力和压力相似的1/13缩尺分岔隧道通风试验平台,构建分岔隧道三维CFD模型,探究了分岔隧道不同分岔形式气流的流动特征和局部阻力系数,并进一步分析了分流结构与减速车道等隧道分岔形式特征对局部阻力系数的影响。结果:表明主线与匝道局部阻力系数随分流比增大呈现先减小后增大的趋势,且在分流比为0.4时达到最小。平行分岔隧道相比定向分岔隧道,主线局部阻力系数差别不大,而匝道局部阻力系数存在较明显的差异,分流比较小时,平行分岔隧道匝道局部阻力更大,分流比较大时则相反。增设减速车道,分流比较小时会减小匝道局部阻力系数,但会增加主线局部阻力系数,分流比较大时则相反。结论:研究结果可为分岔隧道的通风设计提供参考。

Aims:With the improvement of urban construction level and intensity,there are more and more bifurcated tunnels with ramps.In response to the difficulty of ventilation design in bifurcated tunnels,it is urgent to explore the influence of tunnel bifurcation form on the local ventilation resistance characteristics of dividing flow.Methods:By building a 1/13 scale bifurcated tunnel ventilation test platform that synchronously met the similarity of resistance and pressure and a three-dimensional CFD model of bifurcated tunnel,the flow characteristics and local loss coefficient of different bifurcated forms of bifurcated tunnels were studied.And the influence of the tunnel bifurcated forms such as the diversion structure and the deceleration lane on the local loss coefficient was further analyzed.Results:The results showed that the local loss coefficient of the main line and ramp decreased first and then increased with the increase of the diversion ratio,and reached the minimum when the diversion ratio was 0.4.Compared with directional bifurcated tunnels,there was little difference in the local loss coefficient of the main line,but there was an obvious difference in the local loss coefficient of the ramp.When the diversion ratio was small,the local loss of the ramp of the parallel bifurcated tunnel was greater.And when the diversion ratio was large,it was the opposite.The addition of the deceleration lane would reduce the local loss coefficient of the ramp when the diversion ratio was small,but would increase the local loss coefficient of the main line when the diversion ratio was large.Conclusions:The research results can provide reference for the ventilation design of bifurcated tunnels.