| The subway is an important part of modern urban traffic system, which has a veryimportant significance to ease traffic congestion in big cities. Subway station andsubway train is a flow intensity large public places, in case of emergencies, will Posegreat threat to the lives and property of the personnel. So, the in-depth study on subwaytunnel emergency ventilation has great practical significance and practical value.The paper takes tunnel as the research object, through the detailed description ofthe physical model, the numerical calculation model was established on the basis of theactual size tunnel. The tunnel jet ventilation effect, the best central ventilation speed oftrain in blocking working condition, the train fire smoke exhaust and the effect the ofsize of the installation niche on liter pressure jet fan was calculated by Fluent software,and analysis the calculation results.First of all, through the spot test to test and verify the accuracy of the numericalcalculation. Field measurement on Shenzhen metro line3, the comparison between themeasured results and simulation results show that both has the very good consistency,which shows that using numerical method on the subway tunnel study is feasible, andthe result is reliable.Second, using the calculation model built on the subway train in the blockingworking condition, best ventilation velocity was calculated. According to the vehicleshape, the size of the tunnel and the meteorological conditions of Chongqing set theboundary conditions. Through the simulation calculation, we can conclude that whenthe mechanical ventilation and tunnel along with the increase of supply air velocity andair temperature reduction. In Chongqing, when the mechanical ventilation wind speed is2.21m/s can reduce the tunnel temperature to rules and regulations of metro design ofcritical temperature below the danger, guarantee the normal work of the train ofcondenser.At the same time, the subway train fire in the middle of exhaust was analyzed. Thecalculation model is still in Chongqing metro line3. Fire set by the central, intensity of10MW, the fire when the train is located in the middle of the tunnel, the tunnel at bothends for exports. According to the vehicle shape, the size of the tunnel and themeteorological conditions of Chongqing set the boundary conditions. Through thesimulation calculation, We can conclude that in Chongqing area, when the mechanical smoke exhaust wind speed6.5m/s, the CO concentration of toxic gas and flue gastemperature are not reached the degree of direct damage to the human body. Adoptingthe ventilation velocity, not only effectively control the flue gas flow and ensure thepassengers’ safe evacuation in headwaters of fire smoke, but also reduce the extent ofthe passengers affected by fire smoke downstream flue gas temperature and CO toxicgas hazards directly reduce unnecessary casualties.Finally, the impact of mounting dimensions of niches on the jet fan boost effectwas analyzed. Different niches angle (θ=30°,40°,50°), alcove depth (a=1m,1.2m,1.5m), niche segment length (b=7m,9m,11m,13m,15m) and other factors arecombined to obtain45kinds of situations. For all cases, with niche niches installationand no niche niches installation, the jet fan pressure and induce effective length liter arecomparative analyzed, the impact of installation niches size on jet fan boostperformance, and taking into account the jet fans to get the most up pressure and get theminimum amount of niches excavation design, as much as possible to reduce the projectcost. |
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