A practical use of CFD for ventilation of underground works

Any underground work of a minimum length has associated a study of a ventilation system. The traditional way to calculate these systems requires the calculation of the air losses all over the installation in order to select an adequate group of fans. This paper calculates the losses in 138 situations of circular tunnels (varying tunnel diameter, air velocity and surface characteristics), by both traditional and CFD (computational fluid dynamics) means. The results of both methods are compared and adequate correlation has been observed, with CFD values constantly a 17% below the values calculated by traditional means. The paper deals with the main problems commonly encountered in the CFD use, meshing and turbulence, and shows guidance on the practical use of this numerical method. There are also shown the capabilities of the method in simulation domains including machinery of underground works: road headers, dumpers and excavators.