Research on the combustion rate of typical civil aircraft cabin interior wall materials at low ambient pressures

In aviation transportation, which is characterized by low-pressure environments, aircraft fires pose an unpredictable threat. The interior wall materials of civil transport aircraft are predominantly composed of composite materials. The Federal Aviation Administration of the United States and the Civil Aviation Administration of China require experimental validation of their fire-resistant properties. This study aims to address the current research gap by investigating the development patterns of aircraft fires under low-pressure conditions. Specifically, this study examines the combustion rates of interior wall materials in civil aircraft in multiple-pressure environments. The goal is to detect and prevent aircraft fires under low-pressure conditions at the earliest opportunity.

This study investigates the sandwich structure panel material (Panel A) and the laminated panel material (Panel B) used in Airbus aircraft. Panel A comprises the upper and lower layers of resin-based substrates, an aramid honeycomb core intermediate layer, and an adhesive. Panel B is composed of resin-based glass fiber-reinforced laminate. The study is conducted using a low-pressure combustion chamber research facility in Guanghan, Sichuan (96 kPa), and Kangding, Sichuan (61 kPa). Combustion rates and flame phenomena of cabin wall panel materials are examined at 40, 50, 61, 70, 80, and 96 kPa pressure levels. A combustion rate model is applied to adjust the effect of pressure on the combustion rate of cabin wall panel materials. The heat release of the cabin wall panel materials is determined using a cone calorimeter, which enables the assessment of heat release in various pressure environments. Finally, following relevant regulations and standards, a fire penetration resistance test apparatus is constructed to investigate the fire penetration resistance characteristics of cabin wall panel materials under different pressure conditions.

The relationship between the combustion rate and pressure for glass fiber/phenolic resin sandwich panels and glass fiber/phenolic resin laminated panels is approximately and, respectively. According to the fire-base dimensions, the combustion rate-pressure models are and, respectively. The peak heat release rates of aircraft interior wall panels in low-pressure environments are lower than those in atmospheric-pressure environments. When the air pressure drops from 96 kPa to 40 kPa, the peak heat release rate of glass fiber/phenolic resin sandwich and glass fiber/phenolic resin sandwich decreased by about 40.97% and 43.85%, Similarly, compared with atmospheric-pressure environments total heat release significantly decreases under low pressure by 14.20% and 24.71%, respectively. The flame color of aircraft interior wall panel materials shifts from bright yellow at atmospheric pressure to a lower degree of brightness under low pressure. Additionally, the flame height significantly decreases under low pressure compared with the height under atmospheric pressure, with glass fiber/phenolic resin sandwich panels and glass fiber/phenolic resin laminated panels experiencing a reduction of approximately 10.9% and 11.6%, respectively, compared with atmospheric pressure. Research on the fire penetration resistance of aircraft cabin interior wall panels reveals that the char layer of sandwich panel materials becomes more pronounced under low pressure than under atmospheric pressure, indicating increased fire resistance. Conversely, laminated panel materials are minimally affected by pressure.

According to the above research findings, pressure significantly affects the fire characteristics of cabin wall panel materials. This study provides direct relevance to the practical needs of aircraft fire prevention and control, offering data support for aircraft fire prevention efforts.