Numerical investigation on the effect of grille blockage ratio on air flow characteristics of air vents

Abstract

Vents with louvers are an important component in the indoor heating, ventilation, and air conditioning (HVAC) system in providing a degree of freedom to the occupants to direct the air flow and prevent foreign objects from entering or exiting the air ducts. As a result, whether designing air ventilation or any duct design that involves louvers, the influence of louver design cannot be ignored. For vent design, aside from louver angle, blockage ratio is an important factor in air distribution due to its effect on pressure drop and flow distribution to indoor space. The blockage ratio is often described as the ratio of the projected area of the structure in flow direction to the cross sectional area of the domain around the structure. The purpose of this study is to investigate the effect of varying blockage ratios on the air flow characteristics of air vents including velocity and pressure drop. The chosen air vent model for this study is the Proton Wira air vent. Results are obtained using computational fluid dynamics (CFD) analysis and by utilizing the free and easily available open source software via Code-Saturne. The parameters were set according to available literature. The study finds that the pressure drop increases with the increasing blockage ratio. The velocity drops almost 7% for blockage ratio greater than 3 and the pressure drop increases more than 4%.