Study On Aircraft Safety Interval Model Based On Wake Analysis During Take-off And Climb Stage

With the rapid development of civil aviation at home and abroad,the number of aircraft is gradually increasing,and the limited air capacity is facing great challenges,so effectively alleviating the pressure of air traffic flow has become one of the important problems in the development of civil aviation.In order to further reduce the minimum wake interval standard and alleviate the airspace tension under the principle of ensuring safety,the aircraft safety interval model based on takeoff and climbing wake analysis is studied.Firstly,the safety interval standards of wake at home and abroad are compared.Then the separated vortex simulation?DES?model is used,and the simplified wing model is simulated by computational fluid dynamics?CFD?.The wake condition is simulated according to the common take-off climbing angle of attack and V₂ in the take-off and climbing stage.When the vortex length scale is less than the maximum lattice size,the fluid domain is calculated by RANS model,and when the vortex length scale exceeds the lattice size,the LES model is used to calculate the fluid domain.Then the initial eigenvalues of wake are calculated by using the basic parameters of typical civil aircraft in China,and the wake model and aircraft parameters are interfaced with MATLAB software.Finally,the wake safety interval model is studied.Compared with the current wake safety interval standard in China,the wake safety interval standard of the FAA and the EUROCONTROL is smaller than that of the existing wake safety interval standard in China,and the number of aircraft take-off and landing times of the airport can be increased.The simulation results showed that the wake formed by the wing of the winglet structure was rolled up at the tip end of the tip,the tail vortex at the wingspan of the wingtip had a tendency to roll up,the complete vortex core at the 5-fold span was basically formed,and the tail vortex near the 10-fold span reached a stable state,and had strong tail vortex strength.It was found that the Lamb-Oseen,Hallock-Burnham and Adapted eddy current models were more suitable for establishing wake safety interval models.The safe wake interval time of the front machine for A380,B747 and A320 is calculated.The wake safety interval criteria can be established by dividing the wake to extreme risk,potential danger,and no risk based on the roll moment coefficient.To sum up,China can draw lessons from the experience or practices of FAA and the EUROCONTROL to reduce the minimum wake interval standard and alleviate the pressure of air traffic flow.When the safety interval of wake is set,the lower limit distance must be much greater than 10 times wingspan.Lamb-Oseen,Hallock-Burnham and Adapted vortex models can be used to calculate the initial wake during take-off and climbing.By using the principle of no risk,it is possible to reduce the safe interval of wake under the condition of ensuring safety.