The Study of Aerodynamics in Special Parts of a Road Tunnel Using Physical Model

• Main Authors: LA Masslov, H Kanani Moghaddam, MJ Jafari
• Format: Article
• Language: fas
• Published: Iran University of Medical Sciences 2005-10-01
• Series: Salāmat-i kār-i Īrān
• Subjects: Physical Model; Tunnel Ventilation; Aerodynamics; Jet Fans; Road Tunnels; Air Flow
• Online Access: http://ioh.tums.ac.ir/browse.php?a_code=A-10--1-68&slc_lang=en&sid=1

Background and Aims: Ventilation of road tunnels, using jet fans possess a number of featuresresulting from pattern of air flow distribution near solid walls as well as mutual effect of jet fans,dependence of jet momentum (thrust of jet fans) on air flow velocity in the tunnel and otherfactors.Method: In present work, large - scale experimental studies of turbulent jets in stable air mediumor in co - current flow near the solid boundary were performed. Experimental studies wereconducted with two physical models of ventilation system. The hydraulic similarity of physicalmodel and the real system were fulfilled. Measurements were performed with acceptable accuracyand there was shown that distance of jet adherence to the solid surface is specified by relativedistance between jet axis and a wall as well as velocity ratio (ratio of flow velocity to jet velocityof air).Results: Present study provided optimizing the location of jet fans in relation to tunnel walls.These experimental studies likewise theoretical researches proved that turbulent jetcharacteristics created by jet fan scarcely depend on Reynolds number. Thus, physical modelingof such jets can be fulfilled with small Reynolds numbers, corresponding to model flow mode.Conclusion: In particular, with flow velocities close to real value. In this case, apart fromgeometric similarity, there must be provided velocity equality in the model and in the real tunnel(co - current flow velocity) as well as jet velocity behind a fan. In present paper it is intended toillustrate more details of this study.