Transmission of airborne contaminants in airliner cabins

Sagnik Mazumdar, Purdue University

Abstract

Swine flu had already affected 13,000 people in 48 countries within a month of its emergence in Mexico. The risk of disease transmission is augmented by the increasing mobility of people across the world. Nearly two billion people travel on commercial airliners each year. Therefore, knowledge about the transmission mechanism of viruses such as swine flu inside commercial airliner cabins would help to greatly reduce the spread of disease viruses. Previous investigations have suggested that the risk of in-flight disease transmission should remain within two rows of the contagious passenger. But during the SARS outbreak in 2003, passengers seated as far as seven rows from the contagious passenger became infected. Insufficient data and incomplete passenger manifestations make it difficult to ascertain the disease contaminant transmission mechanisms. Hence, the objective of this thesis was to study contaminant transmission inside airliner cabins using experimental measurements and computational tools. A computationally efficient analytical model was first developed to help in understanding contaminant transmission along the length of an airliner cabin. The model could predict the effect of cabin air recirculation, the efficiency of HEPA contaminant filters, and the longitudinal airflow on the contaminant transmission characteristics in the cabin. This model, however, could not capture the effect of local airflows near the contaminant source that had a major impact on transmission. This effect was captured by coupling the analytical model with the Computational Fluid Dynamics (CFD) model for the region near the contaminant source. Furthermore, the applicability of the analytical model is limited as it assumed uniform supply airflow conditions. Experimental and CFD investigations showed that the supply airflow conditions can be highly non-uniform and can significantly influence contaminant transmission inside airliner cabins. For a correct prediction of contaminant transmission using computational tools such as CFD, the diffuser supplying air to the airliner cabin should be accurately modeled. Further experimental and CFD investigations revealed that in-flight movement of passengers and crew members can change the airflow and contaminant transmission inside airliner cabins. Experiments were performed using a one-tenth scale, water-based empty cabin model to facilitate measurements and to generate high quality experimental data using Particle Image Velocimetry (PIV) and Planar Laser-Induced Fluorescence (PLIF). But the understanding of contaminant transmission gained from the empty smallscale cabin could not be extended to a full-scale cabin with seats and passengers as flow similarity is practically difficult to achieve. But the experimental data was used in testing the performance of a CFD model. The CFD model could capture the characteristic flow features and contaminant transport observed in the small-scale model and hence was used in examining the influence of movement on contaminant transmission in full-scale cabin mockups. The results indicate that seats and passengers tend to obstruct the lateral transmission of contaminants and restrict the spread to the aisle of the cabin if a contaminant is released from a moving body. Investigations showed that movement could be the reason behind the transmission of SARS contaminants to passengers seated as far as seven rows from the infected passenger during the SARS outbreak in 2003.

Degree

Ph.D.

Advisors

Chen, Purdue University.

Subject Area

Mechanical engineering

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