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  • Publication
    CFD Modelling of Helicopter Downwash and Assessment of its impact on Pedestrian Comfort
    This study used computational fluid dynamics (CFD) study to investigate the impact of helicopter downwash on pedestrian comfort. The initial stage of the study involves the development of a helicopter downwash model that was compared to experimental values which showed some degree of coherence with areas situated downstream of the helicopter rotor. The initial stage was used to find suitable modelling parameters and an adequate resolution of computational mesh to produce a reliable helicopter downwash model. The final stage of the study is to integrate a helicopter in a built environment and assess the impact of downwash on pedestrian comfort. The concluding stage of the study showed that helicopter downwash effects can impose discomforting conditions in the immediate vicinity of the helicopter along with some minute propagating effects further downstream. Although its magnitude is smaller compared to effects of prevailing wind a local mitigation must be separately planned to deal with the effects of helicopter downwash.
  • Publication
    Investigation of helicopter downwash effect on pedestrian comfort using CFD
    This study employed computational fluid dynamics (CFD) to investigate the impact of helicopter downwash on pedestrian comfort in a representative low-rise streetscape. A time-averaged approach was adopted, where propulsion from the helicopter blades was included using the so-called rotor disc method, as implemented in the open-source software OpenFoam. The modelling approach was validated by comparing downstream air velocities with experimental measurements. The effect of helicopter downwash on pedestrian comfort in a low-rise built environment, representative of an Irish city streetscape, was then analysed. It was found that pedestrian comfort significantly decreased in the immediate vicinity of the helicopter, while minor propagating effects were felt further downstream. The effects of building height, street width and prevailing winds were then examined. In general, it was found that taller buildings tended to improve street-level pedestrian comfort, while narrow streets surrounded by tall buildings tended to funnel the downwash towards the street level, decreasing pedestrian comfort. The main conclusion is that although the effect of helicopter downwash is smaller in magnitude compared with that of prevailing winds, a local mitigation must be established to deal with it.
    Scopus© Citations 3  164