Thermal Comfort of Pilots in the Cockpit of an Airliner Under Unsteady Solar Radiation

Solar radiation transmitted through the aircraft windshield can create a strongly non-uniform cockpit thermal environment and can affect pilot thermal comfort. This study combines a three-dimensional CFD model, experimental air-temperature measurements, and the Fanger predicted mean vote (PMV) model to evaluate airflow, temperature, mean radiant temperature, and comfort response under transient radiative loading. The PMV index is used as a comparative engineering indicator, and its limitations in a reduced-pressure and non-uniform cockpit are discussed. During the simulated two-hour flight, the transmitted irradiance increases from 267 W/m² to 924 W/m². Direct exposure shifts the high-temperature zone over the pilot body with solar position. The maximum local surface temperature reaches about 30.9 °C, and the temperature difference between directly exposed and shaded upper-body regions reaches about 8.3 °C. At a 15 °C supply-air temperature, the baseline airflow distribution still causes local overcooling near the feet, with PMV decreasing to about −1.20. When the transmitted irradiance reaches 641 W/m², redirecting 30 % of the lower-inlet air supply to the main pilot’s left-side inlets, nominally about 0.0050 kg/s in total and implemented as about 0.0052 kg/s in the rounded CFD boundary inputs, reduces the average head temperature by about 2–3 °C and raises the foot-region PMV to about −0.4. At a transmitted irradiance of 861 W/m², an additional 10 % of the top-side inlet flow is needed in this simulated case, reducing the representative PMV near the head-and-shoulder region from 0.91 to 0.45. These results show that adaptive airflow redistribution can reduce radiative overheating while avoiding strong local overcooling in the cockpit.