PIV experimental research on gasper jets interacting with the main ventilation in an aircraft cabin

Gaspers are one of the most widely used nozzles for personalized ventilation systems in transport vehicles. To investigate the interactions between gasper jets and the main ventilation (MV) over a large velocity range, particle image velocimetry (PIV) measurements were made at two scales with four different times between pulses, and the results were spliced. The obtained high-resolution data are not only useful for validating numerical models but also can reflect the interactions between the gasper jets and the MV. In a cabin environment, the decay of gasper jets was accelerated by the influence of the MV and deaccelerated to a lesser degree under cooling conditions by the temperature differences created by heated manikins. The jets from the diffusors of the MV deflected the gasper jets to a similar degree under both isothermal and cooling conditions, and the empirical equations for jet deflection were summarized. The investigation of fresh air transport showed that only 6% of the air delivered to the breathing zone of passengers was the fresh air issued from the gasper, and the rest was the entrained ambient air. Additionally, the influence of the gasper jet on the MV and an adjacent passenger was evaluated at larger scales. The gaspers with medium and high flow rates created a draft sensation, with draft risk values of 35.9% and 47.9% for the gasper user. The use of gasper with medium and high flow rates also caused a 9.6% and 30.4% velocity decrease around the adjacent passenger sitting downstream of MV. Practical implications: This study introduced the cross time between pulses splicing method to solve the problem of PIV measurement of the flow field over a large velocity span, which not only provided high-quality data for validating the CFD model but also revealed airflow characteristics of gasper jets in a realistic cabin environment.