Title

Mitigation of cross-contamination in an aircraft cabin through the use of localized exhaust

Date of Award

2010

Degree Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Mechanical and Aerospace Engineering

Advisor(s)

Thong Q. Dang

Keywords

Aircraft cabins, Local exhaust, Indoor air quality, Personal ventilation

Subject Categories

Aerospace Engineering | Mechanical Engineering

Abstract

This study investigates the use of localized exhaust placed in or near the personal microenvironment (PµE) of seated occupants as a source control strategy for contaminants contained in and carried by the human thermal plume. Through the use of computational fluid dynamics (CFD), various parameters were first studied to ascertain their influence on the ability of the proposed local exhaust strategies to ingest contaminants transported in the thermal plume. From this preliminary work, it was found that the integration of the proposed designs in individual office-type seating was challenging, owing to the inherent limitations of suction-type flow, and that its use in high-density row-type seating yielded much more favorable results. Accordingly, a CFD study was subsequently conducted which incorporated the use of the proposed local exhaust systems in a coach-class aircraft cabin. Using a typical cabin ventilation scheme with appropriate flow rates, reductions in passenger cross-contamination upwards of 60% were witnessed. To further validate the concept, a mockup of a business-class aircraft cabin was constructed which incorporated the proposed local exhaust designs and tracer gas testing was conducted to quantify passenger exposure reductions to cross-contamination. Depending on the local exhaust system employed and the particular flow rates used, exposure reductions of up to 90% were realized in the experimental testing. It was also determined that the inclusion of privacy shells around the seats greatly reduces the mixing of passenger-emitted contaminants and can significantly improve the local exhaust system's ability to ingest contaminants. Finally, a CFD validation study was conducted which compared the collected experimental data with the results of the validation case. It was found that CFD has difficulty resolving cases in which a very large gradient in contaminant concentration exists near the inlet to the local exhaust, e.g. where a point-source is located very close to the exhaust orifice. Conversely, as the distance between the point source and local exhaust increases, the concentration gradient at the orifice decreases and the CFD results agree much better with the experimental data. These findings agree with the conclusions of other CFD researchers and yield much opportunity for future study and enhancement of the CFD techniques used to model contaminant transport in the indoor environment.

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