Simulation Of Indirect Effects Of Lightning On The Fuel Tank Of Large Aircrafts

Lightning protection is an important part of the overall design of large aircraft.It is very important to predict the lightning protection performance of the aircraft and its fuel system by numerical simulation technology in aircraft lightning protection design.This paper mainly focuses on the safety simulation of indirect effects of large-scale aircraft and its fuel tank.1、The electromagnetic environment inside and outside the cabin when the aircraft is struck by lightning is studied.The internal and external electromagnetic fields of the aircraft of which the fuselage is used different materials in four large probabilistic lightning current paths are compared.The simulation results show that compared with the metal skin,the use of CFRP(Carbon Fiber Reinforced Plastics)skin causes the electromagnetic environment inside the aircraft to deteriorate sharply.2、The cable coupling problem in the lightning electromagnetic environment of the aircraft was studied by two methods: full-wave method and field-line-path analysis.Firstly,the influence of the skin material,path,cable position and cable type on the electromagnetic coupling characteristics of the cable in the aircraft was analyzed by the full wave simulation method.Finally,in order to improve the simulation efficiency,the lightning-electromagnetic coupling characteristics of single-line and shielded lines are simulated and analyzed by "field-line-path" analysis method based on BLT equation,and the correctness and efficiency are verified by full-wave simulation.3、The induced current of the lightning coupling to the fuel tank through the cables of Fuel Quantity Indication System(FQIS),which is the main external fuel tank,was studied.By simplifying the FQIS cables,the complicated process of the indirect effects of fuel tank is transformed into the analysis of indirect effects of the specific cables.The current induced by the electromagnetic pulse generated by the lightning which did not directly hit the aircraft was analyzed and compared with that induced by the lighting which directly hit the airplane,which could be coupled to the interior of the fuel tank by the FQIS cable.In addition,the effect of FQIS cable termination load on the lightning coupling current to fuel tank and the effect of FQIS cable shielding damage on coupling current are studied.Finally,the protective measures of lightning indirect effects of fuel tank are obtained.