Rectangular supply ducts with varying cross section providing uniform air distribution

Highlights: • The geometry of supply ducts to provide uniform air distribution is determined. • A simple 1D theoretical model was developed for any duct geometry. • The model is applied for rectangular ducts with variable width. • The impact of dimensionless parameters was investigated. • The theoretical results were validated by successful experiments. - Abstract: A simple 1D theoretical model is suggested, with which it is possible to design ventilation ducts that are capable of providing uniform air distribution on the outlets. Detailed analysis is conducted for rectangular ducts with constant height and variable width. Optimal geometry is described by the width profile. The non-linear differential equation derived from the 1D model is solved numerically. The influence of different dimensionless parameters on optimal geometry is investigated. The model is validated with experiments performed on a unique hydraulically smooth rectangular duct with optimized geometry. The measured flow distributions are uniform with acceptable accuracy.