2D-PIV measurement of isothermal air jets from a multi-slot diffuser in aircraft cabin environment

Mixing air ventilation systems are currently used in commercial aircraft environmental control systems (ECS), which are essential for creating a healthy, thermally comfortable and energy-efficient cabin environment. Based on previous studies, the cabin mixing air distribution is mainly driven by the supply air jets. Therefore, understanding the air jet behaviors within the cabin is necessary for evaluating and improving the cabin environmental quality. In this investigation, we performed a detailed and large-scale 2D particle image velocimetry (PIV) measurement to characterize the isothermal jets in the downstream area of one linear slot of a multi-slot diffuser in a ventilated aircraft cabin mockup. The measurements were taken at different inlet Reynolds numbers (Re) ranging from 1480 to 6940 based on the inlet velocities and the slot height. The PIV results clearly revealed the transitional jet structures in the entrainment process downstream of the slot. The free jets discharging from the slot quickly developed into quasi wall jets due to the Coanda effect. The mean velocity profiles, flow patterns, centerline velocity decay and mean vorticity profiles were then analyzed and compared among different inlet Re. Moreover, the cabin jet characteristics were further compared to results from previous studies. The experimental data and analysis in this research can provide references for designing better side ventilation configurations in single-aisle aircraft cabins.