A uniform air flow distribution design strategy for use in tunnel transverse ventilation systems

Abstract

We focused mainly on a uniform air flow distribution design strategy for a multi-perforated air supply duct with a multi-blade opposed regulation damper. This design is especially required in tunnel transverse ventilation systems, in which a uniform air flow distribution is needed to dilute vehicle exhaust gases or vehicle emissions to acceptable concentrations. First, local resistance coefficients arising when air flows out of the duct through the damper were investigated by means of dimensional analysis and computational fluid dynamics (CFD) simulation, and a mutual authentication was performed with 3D and 2D simulation results. This revealed that the ratio of the velocity in the duct and the damper, and the blade opening angle are the two main factors affecting the resistance coefficient. Second, theoretical analysis based on Bernoulli’s equation was implemented to establish the relationship between the local resistance coefficient and the pressure drop. Based on the simulation results, a uniform air flow distribution design strategy corresponding to the opening angle adjustment was obtained. Finally, a calculation case study was carried out, and sufficient consistency between the theoretical and numerical calculation results was achieved, verifying the reliability of the design strategy.