Modification of Grilles to Improve the Lavatory Environment on an Aircraft

Abstract

Lavatories on commercial aircraft are frequently accessed by passengers and crew members. The lavatory environment is greatly subject to the adopted ventilation strategy, or more specifically the adopted air supply, air exhaust, and the grilles used for air supplementation. In most aircraft lavatories, grilles with bent louvers are present on the lavatory door near the floor, for air supplementation. The strong airflow generated by flushing of the toilet not only produces aerosols inside the toilet bowl but also resuspends deposited particles from the lavatory floor. To improve the lavatory environment, this investigation proposed three ventilation approaches: the use of grilles with straight louvers on the lavatory door near the floor, grilles with bent louvers on the door near the ceiling, and grilles with bent louvers on the lavatory sidewall. The airflow and the concentrations of a tracer gas released into the toilet bowl were measured. Next, the measurement data were used to validate computational fluid dynamics (CFD) modeling. After that, the airflow, the transport of particles released from the toilet bowl and lavatory floor, respectively, the distribution of an odorous gas released from the toilet bowl, and the draught risk in terms of the percentage dissatisfied were modelled by CFD. The results revealed that the original grilles with bent louvers near the bottom of the door may not be effective in minimizing the particle exposure or the odorous gas dispersion. Placement of the grilles on the lavatory sidewall generally performed better and thus is recommended for use on commercial aircraft.

Keywords: Lavatory, ventilation, Grille, Toilet flushing, Particle, Odorous gas