Numerical Simulation And Optimization Of Construction Ventilation In The Underground Powerhouse

Problems on construction ventilation can be harmful to the health of constructors and can be a great disadvantage for the construction scheme and project progress to be actualized in the underground cavern construction of power station. However, the traditional ventilation design is based on the empirical correlations and the builder and designer's experience. For the purpose of avoiding the deficiency of the traditional construction ventilation, the ventilation of the underground powerhouse was simulated by the computational fluid dynamics (CFD) to optimize ventilation parameter. In this paper, a 3-D transient single phase models combining high Reynolds number k -εequation for an underground powerhouse was presented. The effect of buoyancy was considered in the momentum equation of the CO transport model, while the effects of inter-phase drag force, lift force, virtual mass force, and density difference between gas and solid, were taken into account in the momentum source of the dust transport model. The PISO algorithm was used to simulate ventilation in the explosion processes of the underground powerhouse. Contaminations migration regularity during the construction ventilation of the first layer of underground powerhouse is analyzed. The simulated results are as follows:Firstly, methane gas distribution of the mine roadway of Ikejima is simulated by CFD. The simulated results are well in agreement with the experimental and numerical simulation work by Nakayama in methane gas distribution. Secondary, three different mesh densities of the coarse, normal and fine are adopted to simulate the ventilation of upstream in the first layer of underground powerhouse. Considering the computer capability and CPU time, the independence of the mesh plotting is obtained.Thirdly, the blasting ventilation in the first layer of underground powerhouse is simulated. There is an eddy zone around the air duct during the ventilation of the underground powerhouse. The velocity has a great deal of difference in the different position at the heading face, while the velocity distribution has the same tendency in different heights at the X-Y section.Fourthly, using a 3-Dsingle phase model, the dynamic CO and dust diffusion in the first layer of underground powerhouse are simulated. The contaminant concentration has a great deal of difference in the different position at the heading face, while the contaminant concentration distribution has the same tendency in different heights at the X-Y section. The migration rule of CO is similar with the migration tendency of the dust.Fifthly, the two ventilation schemes are modelled in the first layer upstream of underground powerhouse. The air volume and pressure distributions of the different ventilation schemes are compared to obtain the optimized ventilation scheme.