Abstract In the ventilation system of highway tunnels, there are a large number of structures of local three-way, variable diameter and bending. In order to study the movement pattern of air flow and loss coefficient of local resistance in this context, the software named Fluent was adopted to analyze the cases of three-way structure (oblique confluence, straight and oblique confluence, oblique shunting, straight and oblique shunting), variable diameter structure (sudden enlargement, sudden downsizing, gradual enlargement and gradual downsizing) and curved air duct and so on. The results show that: for the oblique confluence structure, the area ratio of branch and trunk duct A3/A1 and angle θ between the branch and trunk duct have significant influence on loss coefficient ζ of local resistance, but the section form and flow ratio Q1/Q3 of branch and trunk duct have little influence on ζ; for the oblique shunting structure, the angel θ between branch and trunk duct, the area ratio A3/A1 and flow ratio Q1/Q3 have significant influence on loss coefficient ζ of local resistance while the section form has little influence on loss coefficient ζ of local resistance; for the sudden enlargement and downsizing of ventilation duct, the ratio of two different sections has obvious influence on loss coefficient ζ of local resistance, and all the section should be designed as round form; for the curved duct, the loss coefficient ζ of local resistance will decrease with an increase of bending radius r which should not be smaller than the bending diameter D, and the loss coefficient ζ of local resistance will increase with an increase of bending angle γ and the section should be designed as round form.
Abstract：
In the ventilation system of highway tunnels, there are a large number of structures of local three-way, variable diameter and bending. In order to study the movement pattern of air flow and loss coefficient of local resistance in this context, the software named Fluent was adopted to analyze the cases of three-way structure (oblique confluence, straight and oblique confluence, oblique shunting, straight and oblique shunting), variable diameter structure (sudden enlargement, sudden downsizing, gradual enlargement and gradual downsizing) and curved air duct and so on. The results show that: for the oblique confluence structure, the area ratio of branch and trunk duct A3/A1 and angle θ between the branch and trunk duct have significant influence on loss coefficient ζ of local resistance, but the section form and flow ratio Q1/Q3 of branch and trunk duct have little influence on ζ; for the oblique shunting structure, the angel θ between branch and trunk duct, the area ratio A3/A1 and flow ratio Q1/Q3 have significant influence on loss coefficient ζ of local resistance while the section form has little influence on loss coefficient ζ of local resistance; for the sudden enlargement and downsizing of ventilation duct, the ratio of two different sections has obvious influence on loss coefficient ζ of local resistance, and all the section should be designed as round form; for the curved duct, the loss coefficient ζ of local resistance will decrease with an increase of bending radius r which should not be smaller than the bending diameter D, and the loss coefficient ζ of local resistance will increase with an increase of bending angle γ and the section should be designed as round form.
WANG Xing1 QIN Wei2 MA Jia3 WANG Lei1
.Study on Local Structural Resistance of Ventilation System in Highway Tunnels[J] MODERN TUNNELLING TECHNOLOGY, 2019,V56(5): 104-113
2019, Vol. 56 