Study On The Optimization Of The Long Highway Tunnel Ventilation System On Local Structure

In recent ten years, through the unremitting efforts of the researchers, our country has obtained great achievements in highway tunnel ventilation. For example, the parameters about parts of the highway tunnel ventilation system have been referred in Guidelines for Design of Ventilation of Highway Tunnels(JTG/T D70/2-02-2014). However, there are also some drawbacks. The items and parameters of the local resistance coefficient have not been completely given in exhaust(delivery) ports, tee duct,converging duct and diverging duct, which are necessary for design of long highway tun-nel ventilation system. Therefore, it is time to optimize the local structure of long highway tunnel ventilation system.Consequently, with the piecewise longitudinal ventilation system of the highway tunnel as the object of the research, we set up a metric to grade local resistance loss coefficient to simulate and analyze the important parts of the highway tunnel ventilation system, such as tee pipe, expanding and reducing duct, bending duct and so on.Firstly, the factors having influence on local resistance loss coefficient in tee duct, such as inclination angle, the area ratio of mainstream to affluent, the flow ratio of mainstream to affluent and section shape, have been researched. Also, these factors how to affect the loss coefficient have been analyzed. According to the research, some optimal parameters have been put forward to reduce the loss coefficient.Secondly, aimed at optimizing four different ducts(sudden expansion duet, sudden contraction duct, converging duct and diverging duct), the factors that have influence on local resistance loss coefficient in these ducts have been researched, such as section shape, the area ratio of the post flow section to the after flow section and inclination angle. According to the research, some optimal parameters have been put forward to reduce the loss coefficient.Thirdly, a study has been done about the bending angle, the bend diameter, the bending radius and section shape how to affect the local resistance loss coefficient in bending duct. And according to the study, some optimal parameters have been put forward to reduce the loss coefficient.Finally, combined with the test data of a similar project, we set up the ventilation system model of Er Lang Shan highway tunnel to simulate and analyze expanding duct, reducing duct and bending duct. Eventually, lots of useful conclusions are achieved and some corresponding optimizational suggestions are proposed in this paper.