Regional turbofan aircraft,which are used for medium-short distances,have a heightened risk of high-altitude Wake Vortices(VV)because of their tail-mounted engines and high horizontal tail configurations.For some regi...Regional turbofan aircraft,which are used for medium-short distances,have a heightened risk of high-altitude Wake Vortices(VV)because of their tail-mounted engines and high horizontal tail configurations.For some regional medium-short-range turbofan aircraft,this threat is higher than that for conventionally designed aircraft.To analyze the flight safety of turbofan aircraft during cruise,this study developed a model to assess wake vortex encounters based on evolutionary high-altitude wake flow patterns.First,the high-altitude wake vortex aircraft dissipation patterns were analyzed by combining Quick Access Recorder(QAR)flight data with the wake vortex evolution model.Then,to consider the uniqueness of the medium-short-range turbofan aircraft,the severity of the wake vortex encounters was simulated using an induced roll moment coefficient.The proposed high-altitude wake vortex encounter model was able to identify and assess the highaltitude wake vortex changes,the bearing moments at different altitudes,and the atmospheric pressure conditions.Using the latest wake separation standards from the International Civil Aviation Organization(ICAO),acceptable safety wake intervals for follower aircraft in different scenarios were determined for the safety assessment.The results indicate that compared to mid and low altitudes,the high-altitude aircraft wake vortex dissipation rate is faster,the ultimate bearing moment is weaker,and the roll moment coefficient is higher,which confirm that there is elevated wake vortex encounter severity for regional turbofan aircraft.As safety is found to deteriorate when encountering wake vortices at altitudes higher than 8 km,new medium-short-range turbofan regional aircraft require higher safety margins than the latest wake separation standards.展开更多
In order to overcome the typical limitation of earlier studies,where the simulation of aircraft wake vortices was essentially based on the half-model of symmetrical rectangular wings,in the present analysis the entire...In order to overcome the typical limitation of earlier studies,where the simulation of aircraft wake vortices was essentially based on the half-model of symmetrical rectangular wings,in the present analysis the entire aircraft(a typical A330-200 aircraft)geometry is taken into account.Conditions corresponding to the nearfield phase(takeoff and landing)are considered assuming a typical attitude angle of 7°and different crosswind intensities,i.e.,0,2 and 5 m/s.The simulation results show that the aircraft wake vortices form a structurally eudipleural four-vortex system due to the existence of the sweepback angle.The vortex pair at the outer side is induced by the pressure difference between the upper and lower surfaces of the wings.The wingtip vortex is split at the wing by the winglet into two smaller streams of vortices,which are subsequently merged 5 m behind the wingtip.Compared with the movement trend of wake vortices in the absence of crosswind,the aircraft wake vortices move as a whole downstream due to the crosswind to be specific,the 2 m/s crosswind can accelerate the dissipation of wake vortices and is favorable for the reduction of the aircraft wake separation.The 5 m/s crosswind results in significantly increased vorticity of two vortex systems:the wingtip vortex downstream the crosswind and the wing root vortex upstream the crosswind due to the energy input from the crosswind.However,the crosswind at a higher speed can accelerate the deviation of wake vortices,and facilitate the reduction in wake separation of the aircraft taking off and landing on a single-runway airport.展开更多
The aircraft departure scheduling problem is described comprehensively. A mathematical model is built for solving this problem. Then, a local search algorithm is proposed; based on it, the dynamic tabu search techniqu...The aircraft departure scheduling problem is described comprehensively. A mathematical model is built for solving this problem. Then, a local search algorithm is proposed; based on it, the dynamic tabu search technique is applied, and the related implement techniques are presented. A simulation including condition and results is performed to solve a representative problem. It is concluded that （ 1 ） departure aircrafts of each queue keep the same order comparatively all the lime, and the distribution of the departure time is well-proportioned, which accords with the ＂first-come first-serve＂ principle; （2） the total time costs are minimized, which would economize money and reduce danger; （ 3 ） the optimization result is not exclusive, which means that several approaches can be chosen at will; （4） the solution obtained is the global optimal one, which guarantees the validity of the proposed method.展开更多
基金supported by the National Natural Science Foundation of China(Nos.U2333209,U1733203)the National Key R&D Program of China(No.2021YFF0603904)the Civil Aviation Administration of China(No.AQ20200019)。
文摘Regional turbofan aircraft,which are used for medium-short distances,have a heightened risk of high-altitude Wake Vortices(VV)because of their tail-mounted engines and high horizontal tail configurations.For some regional medium-short-range turbofan aircraft,this threat is higher than that for conventionally designed aircraft.To analyze the flight safety of turbofan aircraft during cruise,this study developed a model to assess wake vortex encounters based on evolutionary high-altitude wake flow patterns.First,the high-altitude wake vortex aircraft dissipation patterns were analyzed by combining Quick Access Recorder(QAR)flight data with the wake vortex evolution model.Then,to consider the uniqueness of the medium-short-range turbofan aircraft,the severity of the wake vortex encounters was simulated using an induced roll moment coefficient.The proposed high-altitude wake vortex encounter model was able to identify and assess the highaltitude wake vortex changes,the bearing moments at different altitudes,and the atmospheric pressure conditions.Using the latest wake separation standards from the International Civil Aviation Organization(ICAO),acceptable safety wake intervals for follower aircraft in different scenarios were determined for the safety assessment.The results indicate that compared to mid and low altitudes,the high-altitude aircraft wake vortex dissipation rate is faster,the ultimate bearing moment is weaker,and the roll moment coefficient is higher,which confirm that there is elevated wake vortex encounter severity for regional turbofan aircraft.As safety is found to deteriorate when encountering wake vortices at altitudes higher than 8 km,new medium-short-range turbofan regional aircraft require higher safety margins than the latest wake separation standards.
基金This work was supported by the National Natural Science Foundation of China(Grant No.U1733203)the Civil Aviation Administration of China’s Safety Capability Construction Program(Grant Nos.TM2018-9-1/3 and TM2019-16-1/3).
文摘In order to overcome the typical limitation of earlier studies,where the simulation of aircraft wake vortices was essentially based on the half-model of symmetrical rectangular wings,in the present analysis the entire aircraft(a typical A330-200 aircraft)geometry is taken into account.Conditions corresponding to the nearfield phase(takeoff and landing)are considered assuming a typical attitude angle of 7°and different crosswind intensities,i.e.,0,2 and 5 m/s.The simulation results show that the aircraft wake vortices form a structurally eudipleural four-vortex system due to the existence of the sweepback angle.The vortex pair at the outer side is induced by the pressure difference between the upper and lower surfaces of the wings.The wingtip vortex is split at the wing by the winglet into two smaller streams of vortices,which are subsequently merged 5 m behind the wingtip.Compared with the movement trend of wake vortices in the absence of crosswind,the aircraft wake vortices move as a whole downstream due to the crosswind to be specific,the 2 m/s crosswind can accelerate the dissipation of wake vortices and is favorable for the reduction of the aircraft wake separation.The 5 m/s crosswind results in significantly increased vorticity of two vortex systems:the wingtip vortex downstream the crosswind and the wing root vortex upstream the crosswind due to the energy input from the crosswind.However,the crosswind at a higher speed can accelerate the deviation of wake vortices,and facilitate the reduction in wake separation of the aircraft taking off and landing on a single-runway airport.
基金The National Natural Science Foundationof China (No.60134010)
文摘The aircraft departure scheduling problem is described comprehensively. A mathematical model is built for solving this problem. Then, a local search algorithm is proposed; based on it, the dynamic tabu search technique is applied, and the related implement techniques are presented. A simulation including condition and results is performed to solve a representative problem. It is concluded that （ 1 ） departure aircrafts of each queue keep the same order comparatively all the lime, and the distribution of the departure time is well-proportioned, which accords with the ＂first-come first-serve＂ principle; （2） the total time costs are minimized, which would economize money and reduce danger; （ 3 ） the optimization result is not exclusive, which means that several approaches can be chosen at will; （4） the solution obtained is the global optimal one, which guarantees the validity of the proposed method.
