Abstract:

The rational layout of the ventilation system in underground traffic turning platform (UTTP) is very important. Hence, scaled model tests and computational fluid dynamics (CFD) simulation are carried out to reveal the influences of jet fans and ventilation strategies on the air flow in the UTTP. The results indicate that: (1) When the direction of the fan jet is towards the opening section, the distances from the 630 mm, 900 mm and 1 120 mm jet fans to the opening section are supposed to be greater than 40 m, 50 m and 65 m respectively to ensure the pressureboosting coefficient Kj can reach the maximum value. (2) Jet fans with large diameters have a greater Kj, but they usually occupy larger crosssection space and longer jet inducing length; thus, the selection of jet fan diameters should be carefully considered according to the length and height of the linking tunnel. (3) The ventilation strategy of open jet fans in the same side should not be applied to UTTP; instead, diagonal pumping is the most suitable way, which would reduce the pollutant air mixture ratio to the lowest and increase the ventilation efficiency to the highest.

Key words: underground traffic turning platform (UTTP), scaled model test, computational fluid dynamics (CFD), ventilation, jet flow, flow field analysis