Set the ratio of the length of the fire point to the tunnel entrance to the total length of the tunnel B, and calculate the number of jet fans that need to be operated when the fire occurs at any position. It is a calculation result assuming a critical wind speed of 2 m/s. According to the calculation results, 44 jet fans can be installed according to the normal operation design. Even if 8 fire stops, it can ensure that the wind speed in the cave is not less than 2.869m/s when the fire occurs at any position. One-way traffic is changed to two-way traffic, and the maximum allowable concentration of CO is 200ppm, and the vehicles are set up and downhill. In Fig. 3, the two-way normal section module is replaced, the parameters are input, and the traffic volume is adjusted so that the CO concentration reaches 200 ppm while satisfying the total pressure balance. After trial calculation, the allowable traffic volume is 574 veh/h, and the upper and lower 287 veh/h.
Single vertical well suction type longitudinal ventilation, normal operation calculation of tunnel basic conditions and calculation parameters, calculated shaft bottom pressure and main fan pressure, and number of jet fan configurations in each section. Ventilation needs in unexpected situations, both ends of the tunnel must be Install a certain number of fans, then contact the model selection of the main fan of the shaft and the pressure that can be provided. Finally, determine the optimal configuration scheme: the left section of the tunnel: 10 sets of jet fans, decompression; the wind speed inside the tunnel It is 7.44m/s. The right section of the tunnel: 8 sets of jet fans are required for supercharging; at this time, the wind speed in the tunnel is 3.19m/s. The main fan of the shaft: 4 units are required in parallel, and the Qg of each air volume is 137.3m3/s. The pressure Hg is 1435.2Pa. Traffic Control Calculation When the actual traffic volume is less than the designed traffic volume (this situation often occurs in the early stage of operation and low traffic peak period), it is necessary to reduce the number of opening of the jet fan, and sometimes even shut down the main fan of the shaft.
The LVSRT program makes it easy to design different forms of longitudinal ventilation systems. Not only is the calculation result reliable, but it can also be used for ventilation control calculations in the event of fire and traffic control. Table 4 The optimal combination of different wind turbine operation combined traffic volume / vehh-15006007008009001000 axial flow fan, jet fan nI846410nII6262083 Conclusion According to the idea of ​​the combined structure method, the highway tunnel longitudinal ventilation system is decomposed into different basic modules, and then In the Matlab language environment, the free combination of any form of longitudinal ventilation system is realized, and numerical simulation is carried out by LVSRT. It solves a large number of model establishment and calculation in the preliminary design stage of the longitudinal ventilation scheme of highway tunnels, and can be used for numerical simulation of ventilation control when fire occurs and when traffic volume changes. The research results of this paper can be used not only for the comparison and selection of the preliminary design stage of the long road tunnel ventilation scheme, but also for the physical experiment scheme of the optimization stage. And the idea of ​​"combined structure" can be extended to the design of semi-horizontal ventilation, full lateral ventilation and mixed ventilation schemes, and further research on fires will be discussed separately.
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