MEASUREMENTS OF NATURAL VENTILATION WITHIN A MODEL SPORTS STADIUM USING MAGNETIC RESONANCE IMAGING AND PLANAR LASER INDUCED FLUORESCENCE

The natural ventilation dynamics of a model sports stadium are investigated experimentally. Specifically, a laboratory scale idealized sports stadium model is considered with generic ventilation features such as an asymmetric roof opening, roof slits, and entrance and egress tunnels. Time-resolved 2D concentration measurements external to the stadium are conducted using planar laser induced fluorescence (PLIF). Time-averaged 3D measurements of the flow velocity field internal and external to the stadium are performed using magnetic resonance imaging techniques. Both experimental techniques utilize the same water channel facility operated at fully turbulent Reynolds numbers based on the stadium height. A passive scalar contaminant is injected in the vicinity of the stadium to understand how contaminant infiltrates and exfiltrates the structure. The freestream wind angle is varied to quantify how alignment of various geometric features with the prevailing wind direction alters the internal flow structure within the stadium and couples to the contaminant transport. Results show that both the time-averaged and time-resolved concentration fields exhibit important sensitivity to the wind direction. The conclusions suggest that the novel combination of laser-based and medical imaging techniques provides a unique means to understand complex natural ventilation patterns with application to urban air quality and emergency response.