Based on the study of the performance of existing duct leakage detection system of commercial aircraft

an improved leakage detection system based on multilayer insulation design method was proposed. Also

the calculation method of multilayer insulation design was derived with engineering calculation method and the calculation of the insulation with different diameters was conducted. Meanwhile

in order to testify the accuracy of the method

the leakage detection experiment platform was built

and the outside surface temperature of air insulation in different air temperatures was obtained. Also

the influences of the number and the diameter of the diversion channel on the insulation calculation were investigated by numerical simulation. Finally

an optimized structure of the air detection system was proposed. The results show that the improved leakage detection system with quick diversion performance is superior to the traditional leakage detection system since the leakage signal can be detected in time and the alarm system can react quickly. Besides

the outside surface temperature of the insulation is averagely 23.08 percent larger than that of test

and decreases with the diameter and the number of the diversion channel. Also

as the number of the diversion channel increases

the influence of the diversion channel is more remarkable. This work could be helpful to domestic design of China's civil-aircraft ducting system.