CFD Analog Simulation And Experiment Study On Longitudinal Ventilation Of Sewer Tunnel

Along with continuous development of national urbanization, urban infrastructures have already been the mainstay and lifeline of city development. As one of common infrastructures, tunnel's length and quantity are gradually increasing, the sewer mountain tunnel has already been constructed in recent years. Overseas and domestic researchers pay more attention to the tunnel ventilation.On the basis of tunnel ventilation theory and engineering cases, this thesis sums up the primary layouts (forms), features and applications of ventilation system of large and medium tunnels during not only construction period but operational period, studies the ventilation system of sewer mountain tunnel, being part of the sewer discharge project of Longdongbao district, Guiyan, China.According to the theory of incompressible fluid flowing in the stationary diameter pipeline, the ventilation and mass transfer mathematical model are established. By utilizing air dynamic theory, the importance of the shaft, the relationship of wind and stack pressure, and the effectiveness of natural ventilation will be compared with the tunnel without shaft. The thesis demonstrates the feasibility of natural ventilation to control concentration of noxious gas in the sewer tunnel.By carrying on dimensional analysis and similitude theory, the relationship of various physical quantities which attribute the law of air flow will be discussed, the conditions of similitude will be deduced, and scale model of sewer tunnel will be set up. Through test measurement of carbon dioxide concentration in the three type of wind pipe systems, namely, non-branch system, one-inlet and two-outlet system and two-inlet and one-outlet system, the distribution function of CO2 concentration in the different ventilation systems will be fitted, and the relational curve of these functions and the air rate will also be plotted. Meanwhile, the tunnel ventilation model is simulated by CFD numerical calculation software, AirPak, and the CO2 and H2S concentration fields in the tunnel model will be obtained. In order to prove the reliability of computer simulation, some test data under permit condition are compared with the result of simulationThe research of tunnel ventilation system, especially road and railway tunnels, has already been studied for one century in overseas and domestic. Since the ventilation of mountain sewer mountain tunnel is particular, there is little similar...