公路隧道合流段下游压力分布及通风系统优化

Pressure Distribution at Lower Position of Merged Section and Optimization of Ventilation System in Highway Tunnel

借助CFD方法,针对不同隧道合流角、不同风量分配比等情况,对公路隧道合流段下游通风气流组织和压力场分布特性进行了三维模拟分析。研究结果表明在隧道合流一定的前提下,随风量分配比的增加,动压、全压增大,静压减小;其中,动压增大幅度较大,且分配比较大时合流处初始静压出现负值。当合流角增加时,动压、静压、全压均会增大,且角度越大增幅越明显。此外,随着距合流位置距离的增加,涡流区静压、动压变化趋势相反,稳定流后压力沿纵向降低。建议将风机布置在合流下游稳定流动区域,隧道设计时尽可能减小合流夹角,主道与闸道的风量分配尽可能对称。

Using CFD technology,a numerical 3D simulation based on a merged section of a highway tunnel is developed to analyze the air distribution and pressure diffusion at lower position of the section.The different convergence angles and different distribution ratio of air volume are worked out.The results show that,under the premise of the same convergence angle,with the distribution ratio of air volume increases,dynamic pressure and total pressure increase,but static pressure decreases.Static pressure is negative when under a large distribution ratio.The more convergence angle increases,the greater dynamic pressure,static pressure and total pressure rise.What＇s more,with growing distance from the merged section of tunnel,static pressure has an opposite trend with dynamic pressure in vortex area,and all pressures reduce along the longitudinal direction of tunnel in steady flow.Fans should be set at low position of merged section where airflow is steady.It is recommended to reduce convergence angle and to give symmetrical airflow distribution as far as possible.