Performance and flow dynamics of heavy air curtains using experiments and numerical simulations

• Published in: Environmental fluid mechanics (Dordrecht, Netherlands : 2001) Netherlands : 2001), 2024-10, Vol.24 (5), p.875-898
• Main Authors: Agrawal, Tanmay, Agarwal, Shresth, Chalamalla, Vamsi Krishna, Jha, Narsing Kumar
• Format: Article
• Language: English
• Subjects: Air; Air curtains; Air temperature; Buoyancy; Classical Mechanics; Commercial buildings; Deflection; Density ratio; Dye penetrants; Dyes; Dynamic structural analysis; Earth and Environmental Science; Earth Sciences; Effectiveness; Environmental Physics; Hydrogeology; Hydrology/Water Resources; Mean temperatures; Momentum; Numerical simulations; Oceanography; Original Article; Performance evaluation; Simulation; Thermal comfort; Velocity
• ISSN: 1567-7419; 1573-1510
• DOI: 10.1007/s10652-023-09948-8

Air curtain devices (ACD) are commonly installed in domestic and commercial buildings to suppress the buoyancy-driven exchange flow through a doorway opening. Generally, the operating density of an ACD is equal to that of the indoor space making it neutrally buoyant. In the present study, we evaluate the performance of heavy air curtains where the operating density of the ACD is higher than that of the ambient fluid. The primary objective is to quantify the air curtain effectiveness, E , that determines the thermal comfort of building occupants based on the mean temperature inside the interrogated region. Experiments and numerical simulations are conducted and validated for various values of deflection modulus, D m , that compare the relative magnitude of the jet momentum and transverse stack effect due to buoyancy. The other important non-dimensional parameter is the density ratio, S , which compares the extent of added buoyancy in ACD to that of across the doorway. In addition, the velocity dynamics of the air curtains are compared with an isothermal jet to understand the underlying effects that the buoyancy causes on the jet development. The general structure of air curtains that characterize the jet inclination and penetration is visualized through injecting a dye, and it agrees very well with the buoyancy distribution obtained using simulations at different D m . Upon introduction of an assisting buoyancy, it has been found that the infiltration reduces by 25% compared to a neutrally buoyant air curtain for practical values of D m . Article Highlights Heavier air curtains are more effective as compared to the neutrally buoyant air curtains. The deceleration of mean centreline velocity is more prominent at smaller deflection modulus. Stability may be achieved at slightly smaller deflection modulus for heavier air curtains.