During aircraft engine ground testing, a large quantity of air is accelerated through an enclosed test facility. Acoustic measures are required to limit noise emissions, but silencers and other restrictions inevitably introduce aerodynamic pressure losses.
FlowMotion used CFD to analyse the airflow through a sound-attenuated aircraft ground-test facility. The objective was to position and design the outlet silencer so that noise could be reduced without creating an excessive aerodynamic restriction.
An excessive pressure loss across the silencer can alter the complete flow pattern inside the building and promote large recirculation zones. Instead of leaving the facility efficiently, part of the propeller or engine-driven airflow may then circulate back through the hall.
The CFD calculations provided the local velocity and static-pressure fields through the facility and silencer. The pressure distribution and wall shear stresses on the silencer surfaces could also be integrated to determine the resulting aerodynamic forces.
The analysis therefore allowed acoustic requirements, pressure loss, internal recirculation and structural aerodynamic loading to be considered together during the design process.
