Impact of air distribution system on quality of ventilation in small aircraft cabin

• The quality of ventilation in a cabin of a small aircraft was studied.
• The quality was assessed based on local mean age of air.
• Mixing, modified mixing and displacement ventilation were studied.
• The best quality of ventilation was reached with modified mixing ventilation.
• Mixing and displacement ventilation failed in case of hot ambient conditions.

A ventilation system of sufficient performance is the basic condition for comfort and health risk free environment in enclosed aircraft cabin spaces. The airflow pattern and spreading of fresh air into the cabin space mainly depend on the type of the air distribution system and location of heat sources/sinks. The present study deals with the investigation of the dependency between the type of the air distribution system and indoor air quality in a cabin of a small transport aircraft. The mock-up interior geometry of a small aircraft cabin for nine passengers was adopted for the investigation. Three types of the air distribution system were investigated: a typical mixing ventilation system, a modified mixing ventilation system and an under-aisle displacement ventilation system. The quality of ventilation was assessed based on the local mean age of air using CFD software Star-CCM+. At first, the CFD model of a typical mixing ventilation was validated against the experimental data of airflow in the mock-up of the small aircraft cabin. The validated model was then used for the evaluation of the three distribution systems under cold, mild and hot ambient environment conditions from the point of their performance for several typical aircraft operational conditions. Results of the study show a strong dependence of the air distribution systems performance on the ambient conditions. The most stable air distribution was reached with the modified mixing air distribution system. Other types of ventilation systems failed to provide sufficient ventilation and cooling under hot ambient conditions.