Numerical study of effects of deflected angles of jet fans on the normal ventilation in a curved tunnel

摘要

A computational study was carried out to investigate the effects of deflected angles of jet fans, equipped with silencers, on the tunnel ventilation system. An optimal deflected angle for the normal ventilation in a curved tunnel was proposed. As the fans deflect an angle (β) of 3° towards the convex wall, maximum pressure-rise coefficient and lowest wall shear stress on the ceilings were obtained. An offset of jets on the cross-section was observed for various deflected angles (β) initially. For β = 3°, a relatively gradual velocity profile was obtained as compared to the other values of β which yielded steep velocity profiles downstream. The static pressure increased gradually and overlapped with each other for various values of β initially. The divergence in the longitudinal pressure curves was found when the jets arrived at the curved walls. A relatively shorter distance was required for the pressure-rise to complete at β = 3°.