Experimental identification of key parameters contributing to moisture accumulation in an aircraft section

Abstract

Aircraft can acquire large amounts of moisture in its insulation layers. The trapped moisture increases the aircraft's weight, degrades thermal and sound insulation performance, induces microbe growth, and causes various types of corrosion. It is known that moisture accumulation varies with flight conditions. However, the specific effects of individual parameters, such as flight altitude, cabin air pressure, cabin air temperature, and relative humidity, on moisture accumulation remain unknown. This investigation measures moisture accumulation mass in a reduced-scale mockup of an aircraft section. The mockup is composed of a metallic shell, porous insulation blankets, a ventilation system, heat and moisture generation devices, etc. The mockup is placed in a psychrometric altitude chamber in which the air pressure and psychrometric parameters can be varied in order to simulate different flight conditions. The moisture mass accumulated within the insulation blankets and on the interior skin of the shell is weighed on a digital precision balance. The results reveal that flight altitude and cabin air relative humidity have the greatest effect on moisture accumulation amounts, while cabin air pressure and temperature play relatively weak roles. Greater moisture gain is observed at a high flight altitude and a high cabin humidity level, and vice versa.