Optimization Of The Longitudinal Tunnel Ventilation

At present, the total length of the tunnel in our country has exceeded4600kilometers, the highest in the world. According to statistics, the running cost of the tunnel ventilation is proportional to the cube of tunnel length, tunnel ventilation technology has become a key factor in the development of road tunnel. Therefore, the study of tunnel ventilation system has a great economic value.In this paper, we use numerical simulation and model test method. From the comparison of water jet and air jet, water jet model has advantages of the space is little, high plasticity and so on, so we choose water jet model to do research on tunnel ventilation.1) The paper had set series measuring surface after water jet tube, and carried on the velocity experiments on each fracture surface.2) Conditions of different jet distance, the paper had tested the jet’s influence in the tunnel model, and choose the best distance of two fans.3) In this paper, we had established the model with the help of professional software Gambit. In the places where flow velocity or pressure has dramatic changes dense model mesh, to ensure to ensure accuracy of Fluent calculation.4) In order to study the location of jet fan’s influence on air flow state in the tunnel, the software Fluent had simulated it under the conditions of different jet distance and different installation height.Through the model experiment and numerical simulation, drawn the following important conclusions:1、With water as the fluid medium, and through measurement experiments of flow velocity and static pressure, found that when Re>1.5×105, the Euler number has been basically stable.2、When lateral distance between jet is less than12cm, with the increase of the distance, due to the effect between two jet, rising pressure increasing; when lateral distance is more than12cm, jet has interaction with tunnel wall, the pressure drops. When lateral distance is between10cm and14cm, jet booster effect is better.3、At first, comprehensive influence coefficient is increase with the lateral distance between jet; later, with the increase of the lateral distance, comprehensive influence coefficient is decreasing. So the K curve into a parabolic shape, and when lateral distance is between10cm and14cm, comprehensive influence coefficient is good, corresponding with the pressure curve.4、Jet fan’s comprehensive influence coefficient with the increase of the installed height show a trend of decrease. When H=5.6m is the best, K=0.821; when H=6.4m is the worst, K=0.793.5、In front of the fan, jet fan’s influence is smaller, about3-4m; after the fan, fan jet’s influence is bigger, about between120～150m, and with the decrease of the fan installation height showed a trend of increase.