Numerical investigation of pilots' micro-environment in an airliner cockpit

Airflow in the cockpits of commercial airliners could be substantially different and more complex than it in passenger cabins, while simply referring to the standard of passenger cabin may not effectively achieve optimum ventilation or ensure a comfortable working environment for pilots. This study numerically investigated the ventilated Boeing 737 cockpit by analysing its airflow and thermal distribution inside, especially in pilots' microenvironments, under various in-flight conditions (number of personalised jet-inlets, window heat exchange, etc.). Gaseous contaminant CO2 released from pilots was analysed in relation to its concentration distribution and potential lock-up phenomena in pilots' micro-environments, followed by quantitative analysis of pilots' thermal comfort and air quality. The outcomes demonstrated that the window heat exchange had significant impacts on pilots' thermal sensation and could induce severe thermal stratification around pilots' head level. The most effective CO2 removal rate was achieved by initiating windshield inlets in combination of the side diffusers. Further adding personal gaspers did not significantly alleviate the CO2 concentration in pilots' microenvironment but may potentially compromise their thermal comfort. Also, the overwhelming numbers of personalised inlets could hardly provide superior ventilation performance or ensure consistent air quality and could be impractical to use sometimes. It is suggested that future optimisation of the environmental control system could rely more on the global airflow circulations induced by larger or wider diffusers rather than the local complex jet flows from high number of personal gaspers.