Smoke Emission and Distribution Characteristics of Overloaded Wire Insulations under Microgravity

With the development of manned space technology, spacecraft safety and fire prevention have attracted more and more attention. Due to the disappearance of buoyancy in microgravity, the fire early monitoring, detection and alarm technologies designed based on the ground experimental results are not suitable for spacecraft. It is necessary to develop fire early monitoring technology in microgravity. Smoke is an important early monitoring signal for fire prevention both in normal gravity and microgravity. Under microgravity, fire is mostly caused by overload or aging of wire insulations. In order to study the smoke emission characteristics of wire insulations under microgravity, we carried out the overload experiments of wire insulations on board the SJ-10 Chinese recoverable satellite. The smoke generation characteristics captured by laser extinction methods, and a large number of experimental data in the real microgravity environment were obtained for the first time. In this paper, the smoke volume fraction in the early and axisymmetric stages of smoke emission from the wire insulating layer are obtained by using the method of Abel transform and convolution, and the MATLAB algorithm program is compiled. In the later stage of smoke emission, it does not show axisymmetric distribution, but the laser extinction results can be used for obtaining the smoke emission trajectory. According to the results, edge jet smoke emission modes in the early stage of ignition of wire insulation in microgravity are quantitatively analyzed. The effects of insulation thickness, overload current and insulation material on smoke emission are discussed.