Investigations Of The Thermal Comfort In An Aircraft Cabin

Due to the increase of flying time and aircraft heating loads, the thermal comfort in a cabin has been researched widely in the environmental control system engineering. The aeroheating near the cabin skin, airflow in the cabin and aircraft heating loads have been investigated in this dissertation using RANS and emprical formulas method. The results and conclusions are described briefly as follows:(1) Aeroheating on the aircraft skin has been investigated using RANS technique. Effects of free-stream Mach number M∞(0.8～2.0) and flying hight (5～11km) on the aeroheating are studied for angle of attack 0°and Reynolds number 10 7 based on the aircraft wingspan. The work provides an insight into the generation mechanism of aeroheating based on some typical variables, including the wall temperature, skin friction coefficient, velocity gradient in the normal direction and heat flux on the surface centerlines. Due to the growth of velocity gradient in the normal direction near the wall, the mean wall temperature, skin friction coefficient and heat flux on the surface centerlines increase with M∞. Moreover, a specific equation between the mean wall temperature of the centerline, free stream temperature and M∞has been obtained.(2) The total heating loads and its component in a cabin have been calculated using some emprical formulas. According to the aeroheating, heating load induced by heat transfer through the aircraft skin is obtained using a multi-block domain decomposition method. Moreover, heating loads generated by solar radiation, human body and electrical equipments are also considered. At M∞= 1.5,α= 0oand H = 5km, results show that heating loads induced by heat transfer through the aircraft skin and solar radiation through the transparent surface make a main contribution for the total heating loads, which indicates that these heating loads must be paid prior attention to in the cabin environmental control system engineering.(3) Distributions of airflow including velocity and temperature in a simplified cabin model have been investigated numerically at M∞= 0.8, H = 11km. By introducing military psysiology standard, the thermal comfort in the cabin has been evaluated. Meanwhile, solar radiation, internal radiative heat transfer between different surfaces, human body and electrical equipments are considered when dealing with the thermal boundary conditions. Results show that the average air velocity is about 0.15m/s and temperature 20℃around the human body, i.e., the cabin environment satisfies thermal comfort in terms of the airflow velocity and temperature according to the military psysiology standard. Last but not least, the air supply scheme is optimized and the effects of inlet velocity on thermal comfort are discussed.