铁路隧道射流与洞口风道组合式通风效果分析

射流风机与洞口风道组合通风效果一直是学术界和工程界关注的关键科学问题,在长度超过5km的内燃牵引隧道中,射流风机并未有效阻止风流从洞口隧道内流出,未达到设计通风效果。采用CFD计算软件FLUENT建立三维非线性力学模型,研究洞口射流风机安装断面连接方式、轴流送风口风速、射流风机台数关键因素影响效果。射流风机安装处设置渐变过渡段后,风机吹出的风流可以平稳的进入隧道,从洞口引入新风效果明显;在同样的风量下,送风口风速不同,产生阻力也不同,对洞口端引入新风产生影响,设计中应适当降低送风口风速;在洞口设置同样的射流风机,轴流送风道送入的风量不同,洞口端隧道内风流的状态不同,当送风量大到一定程度时,将产生洞口段隧道风流流出,设计中洞口射流风机的台数应根据送风道的送风量进行调整。

Analysis on Combined Ventilation System Containing Both Jet Fan and Air Duct Used for Railway Tunnel

Consisting of both jet fan and portal air duct,the combined ventilation system is a critical scientific subject which is focused on all the time by both academic circle and engineering circle.In an internal combustion traction tunnel of more than 5 km long,it is impossible to achieve ideal designed ventilation efficiency only by using jet fans,because the jet fans cannot effectively stop the outflow of the air current from tunnel portal.For this reason,through establishing three-dimensional mechanical model by using FLUENT software of CFD series,this paper researched the influences of critical factors,including the connection ways of jet fans installed at the portal cross-section,the wind velocity of air supply outlet of axial flow fan,and the number of jet fans.The research shows that,after setting up a transition section at the place where the jet fans are,the air current blown from the jet fans can enter into the tunnel smoothly,that is to say,the fresh air can be effectively led into tunnel from the portal.On condition of the same air supply volume,the wind resistance will change with the change of wind velocity at the air supply outlet,which has effect on the fresh air importing from the portal,so the wind velocity should be appropriately weakened at the air supply outlet during design.On condition of the same jet fans,the situation of air current within tunnel portal is different when air supply volume from axial-flow air duct is different;and when the air supply volume rises up to a certain extent,the air current will outflow from the tunnel portal,so the number of jet fans at the portal should be adjusted according to the air supply volume of air duct during design.