Prediction of airflow with swirl in perforated polyethylene tubes

The influence upon flow of fan induced inlet swirl is examined for two commonly used sizes of uniformaly perforated polyethylene ventilation tubes (polytubes). Swirl is present at inlet of most polytubes that are directly connnected to a supply fan wether or not an antiswirl device is used. Four experimentally obtained inlet swirl angles are examined using swirl modified pressure recovery coefficients, pipe friction factors, and orifice discharge equations.