یک سیستم تهویه جایگزین نوآورانه برای کابین های هواپیمایی An innovative personalized displacement ventilation system for airliner cabins

1. Introduction The transmission of airborne infectious diseases, such as influenza [1], tuberculosis [2], and severe acute respiratory syndrome [3], has been observed in commercial airliners. As more and more people travel by air [4], it has become crucial to improve cabin air quality. There is a strong association between cabin air distribution and the transmission of airborne infectious diseases [5]. Therefore, it is important to investigate the air distribution in airliner cabins in order to improve the quality of cabin air. Mixing ventilation systems are prevalently used to control the cabin environment in commercial airliners. A mixing ventilation system supplies clean air through diffusers on the ceiling and then removes the cabin air through exhaust slots on the side walls near the floor. A system of gaspers, which are small, circular, and adjustable vents above the seats, is also installed in most commercial airliners as a personalized ventilation system. The gaspers supply air directly to the passengers and are adjustable for flow rate and direction. To investigate the air distribution in a cabin, several experimental studies have been carried out. For example, Liu et al. [6] used a combination of hot-sphere anemometers and ultrasonic anemometers (UAs) to obtain accurate velocity profiles at the diffusers and the velocity field in the first-class cabin of a functional MD-82 commercial airliner. They found that UAs could be used to accurately measure the distributions of three-dimensional airflow parameters. However, the UA sensor was too bulky for use in small areas. Cao et al. [7] performed a large-scale particle image velocimetry (PIV) measurement to characterize the mixing air distributions inside a partially transparent airliner cabin mockup. They obtained highaccuracy 2-D airflow information and found that the cabin airflows were of low velocity and high turbulence level. Li et al. [8] measured the distributions of air velocity, temperature, and tracer-gas (sulfur hexafluoride or SF6) concentration in the economy-class cabin of an MD-82 airplane with gaspers on and off. The experimental results showed that gaspers in a cabin with mixing ventilation might not be useful for improving cabin air quality, even though the gaspers seemed to supply clean air directly to passengers.