Study On Ventilation Mode Of High-density Diesel Traction Single-track Railway Tunnel

China’s diesel traction railway is generally used for the transport of goods,there is an intensive and high-density development trend.For a long time,there is no basis to determine the mechanical ventilation method for diesel traction single railway tunnel,which undoubtedly caused some obstacles of the tunnel operating ventilation design.Aiming at this problem,in this paper some representative single railway tunnels are taken as the research object,and the operating ventilation model of tunnels in a diesel traction railway line is studied.First,based on the characteristics of the single-track railway tunnel ventilation,a two-dimensional incompressible unsteady flow and unstable flow with moving flow physical model is established,and then the continuity equation,momentum equation and convection diffusion equation mathematical model is established too.By using numerical calculation method,the numerical calculation procedure for the single-track railway tunnel operation ventilation,the established and completed.Then the article analyzes the determination method of pollutant emission intensity and control standard of pollutant concentration.Through the numerical calculation,the wind speed change and the concentration of pollutants are simulated when the tunnel is taken into the corresponding ventilation mode,and then the time used up to pollutant concentration standard of the tunnel is determined.Then,the natural ventilation,the completed jet ventilation method and the inclined vertical ventilation mode have been researched.The results show that:(1)When the allowable ventilation time is 15minutes,if the train speed is 120km/h,the maximum tunnel length of natural ventilation can be 2920m.If the train speed is 70km/h,the maximum tunnel length of natural ventilation can be about 2100m.(2)For some kind of tunnel,through the numerical calculation and the numerical fitting,it is determined that the minimum compliance time of-the longitudinal ventilation mode can be expressed as Tmin＝0.00143/Ltu-0.011Vtr-0.52.When the ventilation time interval is allowed,Longitudinal ventilation is applicable,whereas the mode is not applicable.(3)Certain tunnel in this paper,the inclined shaft adopts the exhaust style to be more reasonable than the air supply.When the train speed is 38km/h,the better position of the inclined shaft is located at 2Ltu/3 of the tunnel,the better shafts distance of two shafts ventilation spaces between 2Ltu/5 to Ltu/2;when the tunnel needs two-way ventilation,single-row ventilation mode can be used,the more appropriate inclined shaft distance is about 2Ltu/5.For the extra-long tunnel ventilation wind speed exceeded under the design conditions,which can’t meet the ventilation requirements.It is recommended to use the 2#,4#and 5#auxiliary channels as the ventilation shafts at the design speed of 70km/h,and take the ventilation mode of the discharge row.At this timc,by adjusting the fan pressure,the ventilation wind speed can be less than 8m/s,the standard time is less than 7.9min,so as to meet the tunnel ventilation requirements.