Ventilation mode changes our safety in buses: Study on “air-rain” flow against chemical and arson attack in public transport vehicles

Abstract

Objectives: Public transport vehicles (PTVs) play a decisive role in development of the urban economy. However, the safety of PTVs is threatened by the man-released chemical or arson attack. It was found that indoor air safety can be greatly improved by employing air-rain ventilation instead of the common ventilation in a PTV.

Methods: Numerical simulations and experiments have been done to prove the effectiveness of the air-rain flow against chemical attack or arson in PTVs.

Results: The research shows that, during a chemical attack, an air-rain flow of 0.1 m/s can constrain the spread of a chemical agent in a very limited zone near its source, which is far away from the passengers’ breathing area in the PTV. During an arson attack, at an air-rain flow of 0.3 m/s, most of the area in the PTV maintains a low temperature for at least 60 s during a fire, which is long enough for passenger evacuation.

Conclusion: Compared to common ventilation, the key characteristic of air-rain ventilation is its resistance to the blending effect of the air. Because of this, the spread of chemical agents, hot gas/combustion products during a fire, and fuel aerosol is constrained to a limited area in a PTV. Passengers are then protected from chemical attack, explosion of fuel aerosols, and high temperatures and smoke. Thus, we can say that this new ventilation mode increases passenger safety in buses.

Keywords:

• Arson
• chemical attack
• public transport vehicles
• indoor air

Additional information

Funding

The support of the China Scholarship Council (CSC) is greatly appreciated.