A CFD research on emission characteristics of pollutants and optimization of airflow organization in a civil aircraft lavatory

Abstract A computational fluid dynamics (CFD) model was developed to simulate the spread of contaminants within an aircraft lavatory when the toilet lid is opened. The pollutant simulation employs the species transport method, and the realizable k-ε two-layer model is chosen as the turbulence model. An automatic optimization model has been established to decide the location and size of the ceiling air inlet. This model is based on the top supply and bottom return airflow organization of the lavatory, with the dimensions and position of the top supply air vent, including length, width, and left-right spacing, as optimization variables, and the contaminant concentrations in the breathing zones of seated and standing individuals as optimization objectives. The results show that without a ceiling air inlet, the dimensionless contaminant concentrations in the standing breathing zone ( P 1 ) and the sitting breathing zone ( P 2 ) are 1; with the addition of an unoptimized ceiling air inlet, P 1 and P 2 are 0.84 and 1, respectively; after optimizing the ceiling air inlet, it is found that when the inlet is located above the washbasin, the contaminant concentrations in the breathing zone of individual is the lowest, with P 1 and P 2 being 0.29 and 0.64, respectively. At this time, the airflow direction changes from vertical to horizontal upon reaching the washbasin, and the horizontal airflow effectively suppresses the dispersion of toilet-emitted pollutants.