2024
Zhou, Y., Hou, Y., Chen, C., and You, R.* 2024. Optimal operations of gaspers for minimizing the exposure risks of airborne disease transmission in an economy-class aircraft cabin. Indoor Environments, Accepted.
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Abstract: Overhead gaspers with adjustable open ratios and flow directions can alter the airflow pattern in aircraft cabins and consequently influence airborne infectious diseases transmission. To achieve the optimal operations of gaspers for minimizing the passengers’ exposure risks, this study developed a Bayesian optimization method based on computational fluid dynamics (CFD). A seven-row, single-aisle, fully occupied, economy-class aircraft cabin was used for the numerical investigation. Two air distribution systems, i.e., a mixing ventilation system and a personalized displacement ventilation system, were considered. First, the open ratios of all the gaspers were optimized by the CFD-based Bayesian optimization method. The optimal operations of gaspers were determined with only 20 trials calculated by CFD using the Bayesian optimization. With the optimal open ratios of all the gaspers, the number of relatively high-risk passengers (exposure index over 0.95) was effectively reduced by at least 55% and 86% under the mixing ventilation and the personalized displacement ventilation, respectively, when compared with the results with all gaspers turned off. Next, the optimal open ratios and flow directions of the gaspers near the index passenger were also determined by the proposed method. With the optimized gasper operations, the number of relatively high-risk passengers was effectively reduced by at least 50% and 67% under the mixing ventilation and the personalized displacement ventilation, respectively.
2023
Hou, Y., and You, R.* 2023. Investigating the impact of gaspers on airborne disease transmission in an economy-class aircraft cabin with personalized displacement ventilation. Building and Environment, 245: 110963.
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Abstract: Overhead gaspers provide directional fresh airflow, and thus affect the local airflow pattern and contaminant distribution. To investigate the impact of gaspers on airborne disease transmission in an aircraft cabin with a personalized displacement ventilation system, numerical calculations were conducted in a seven-row, single-aisle, fully occupied, economy-class aircraft cabin with the computational fluid dynamics (CFD) simulation method. We first investigated the impact of source gasper direction and flow rate on the airborne transmission near the contaminant source. We then investigated the protective effect of the receptor's gasper. For a source passenger's gasper, the direction and flow rate of the gasper flow either increased or decreased the air contaminant transmission to other passengers. Directing the source gasper to the abdomen with a medium flow rate performed best by reducing the receptors' mean exposure index by at least 45%, as this approach minimized the contaminant circulation in the cabin. Turning on a receptor passenger's gasper could be an effective strategy to protect the receptor, and the working mechanism was revealed. The gasper-induced jet flow entrained the surrounding air into the jet region, and the protective effect was related to the contaminant concentration at ceiling level. With a suitable gasper direction and flow rate, the gasper jet formed a virtual barrier between the source passenger and the receptor. When the contaminants were transported upwards to a receptor's breathing zone, turning on the receptor's gasper reduced the contaminant concentration, since the downward gasper jet altered the airflow pattern in front of the receptor.
2019
You, R., Lin, C.-H., Wei, D., Chen, Q. 2019. Evaluating the commercial airliner cabin environment with different air distribution systems. Indoor Air, 29: 840-853.
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Abstract: Ventilation systems for commercial airliner cabins are important in reducing contaminant transport and maintaining thermal comfort. To evaluate the performance of a personalized displacement ventilation system, a conventional displacement ventilation system, and a mixing ventilation system, this study first used the Wells-Riley equation integrated with CFD to obtain the SARS quanta value based on a specific SARS outbreak on a flight. This investigation then compared the three ventilation systems in a seven-row section of a fully occupied, economy-class cabin in Boeing 737 and Boeing 767 airplanes. The SARS quanta generation rate obtained for the index patient could be used in future studies. For all the assumed source locations, the passengers’ infection risk by air in the two planes was the highest with the mixing ventilation system, while the conventional displacement ventilation system produced the lowest risk. The personalized ventilation system performed the best in maintaining cabin thermal comfort and can also reduce the infection risk. This system is recommended for airplane cabins.
