Research On Electromagnetic Interference Effect Of Airborne Signal Transmission Cable In Lightning Environment

With the rapid development of aviation technology,there are more and more kinds of electronic and electrical equipment used in aircraft avionics system.At the same time,in order to meet the design requirements of aircraft lightweight,a large number of advanced composites are used in the design and manufacture of aircraft..This makes the aircraft more sensitive to external electromagnetic interference.Lightning is an important factor that threatens the safety of aircraft.Aircraft flying in the atmosphere will inevitably encounter lightning environment.The harm of lightning to aircraft can be caused by direct effect and indirect effect.Indirect effect refers to the interference and damage caused by part of energy transmitted to airborne equipment under the electromagnetic coupling effect of lightning electromagnetic pulse.The airborne cable is an important way for the lightning electromagnetic pulse coupling into the internal equipment.Based on this,this paper uses CST electromagnetic simulation software to simulate the electromagnetic interference effect of airborne signal transmission cable in lightning environment.Mainly completed the following work.In this paper,the simulation of the coupling effect of lightning electromagnetic pulse of airborne cable is carried out.In the CST cable studio,the electromagnetic simulation model of the cable lightning electromagnetic pulse coupling on the limited conductor ground is established.The influence of different excitation wave application mode,cable length,height from the ground and cable type on the lightning electromagnetic pulse coupling is studied and analyzed.On this basis,the general lightning protection measures for cables are discussed.The simulation results show that when the excitation wave is perpendicular to the ground and the E-polarization direction is parallel to the cable,the coupling effect on the cable is the largest,and the coupling effect is positively related to the length of the cable and the height from the ground.The shielding layer can obviously restrain the coupling effect on the cable.Generally speaking,the shielding effect of tubular shielding layer is better than that of braided shielding layer.In addition,the cable laying mode will also have a greater impact on its coupling effect.According to the standards of SAE ARP-5412 and SAE ARP-5413,the 3D electromagnetic simulation model of the aircraft when encountering lightning stroke is established in CST MS studio,and its transient effect is studied and analyzed.The simulation results show that when the aircraft is hit by lightning,the surface current of the skin is mainly distributed near the lightning current flow.In addition to the lightning attachment and departure point,the current density is relatively concentrated at the discontinuity of the structure and the area with small curvature radius of the skin due to the influence of edge effect.The distribution of space electric field has little relationship with lightning path,and the area with the largest field strength is mainly located in the area with smaller curvature radius of skin.The lightning path has a great influence on the distribution characteristics of space magnetic field,which is similar to the distribution characteristics of surface current.The induced current of the shielded cable is lower than that of the unshielded cable,and the shielding layer can effectively avoid the high lightning induced transient of the core wire.In addition,the surface current of the composite fuselage is higher than that of the metal fuselage because of its poor shielding performance.Due to the worse internal electromagnetic environment and the further enhanced resistance coupling,the induced transient on the cable is also higher than that on the metal fuselage.In this paper,the airborne cable is taken as the research object,and some research results are obtained.These results can provide necessary reference for the selection and use,shielding design and optimization of wiring layout of airborne cables,and also provide necessary data support for the overall lightning protection design of the aircraft.