Research On The Risk Of ARJ21 Aircraft Encountering Wake Vortex Of A330 Heavy Aircraft During Final Approach

Wake vortex is a by-product of aircraft lift.When the following aircraft enters the wake area of the front aircraft,the following aircraft will roll,turbulence,altitude drop and other dangerous phenomena.This dangerous phenomenon is more likely to occur when small and medium-sized aircraft follow the approach of heavy aircraft.Therefore,in order to ensure the safety of operation,various countries have equipped different wake separation between different aircraft types according to the aircraft wake level.Wake separation is one of the important factors that limit the capacity of an airport,but the separation during take-off and landing often ignores the changes in the dissipation law and motion characteristics of aircraft wakes in the near-ground stage,resulting in the current wake separation being too conservative.After the domestic medium aircraft ARJ21 was put into flight operation,due to the lack of aerodynamic response study of ARJ21 encountering heavy aircraft wake,a large wake separation was kept between ARJ21 and heavy aircraft in actual control operation due to the lack of risk assessment of encountering heavy aircraft wake,which greatly limited the takeoff and landing ability and operation efficiency of the airport.In this thesis,medium aircraft ARJ21 followed heavy aircraft A330-200 on the final approach of Runway 20 of Chengdu Tianfu Airport as an example,a systematic study was conducted on the generation and evolution of wake turbulence from the leading aircraft,the aerodynamic response of the following aircraft encountering wake turbulence,and the distribution of the wake turbulence hazard zone of the leading aircraft.The main research work of this article includes:Firstly,based on research conducted domestically and internationally and in combination with existing models,this study investigates the characteristic properties and attenuation of aircraft wake turbulence.Four typical wake-induced velocity models are compared and analyzed,with the Burnham-Hallock wake-induced velocity model selected for subsequent calculations of the aerodynamic forces generated by the ARJ21 encountering front aircraft wake turbulence.Different methods and stages of wake dissipation are analyzed,with the APA(Aircraft Vortex Spacing System Prediction Algorithm)dissipation model selected to calculate the changes in wake intensity of an A330-200 aircraft during the final approach stage,and to explore the influence of different factors on the rate of wake dissipation.Secondly,the evolution law of the front wake of the aircraft at different decision heights was studied.The Reynolds-Averaged Navier-Stokes method was used,and two methods were adopted: constructing a three-dimensional wing and flow field domain structured grid model and compiling a wake vortex tangential velocity model to explore the near-field and far-field evolution processes of the A330-200 aircraft wake at different decision heights during the final approach stage.By analyzing the near-field and far-field evolution processes of the wake,the influence of ground effect on the evolution of the aircraft wake was summarized,and the evolution law of the A330-200 aircraft wake at different heights from the ground was obtained.Next,safety indicators that can be used to quantify the degree of risk of encountering wake turbulence are selected.Based on the way the ARJ21 enters the front aircraft wake turbulence field during the final approach stage,an aerodynamic response model for the ARJ21 encountering wake turbulence is established.A strip algorithm based on the induced velocity distribution of the front aircraft wake turbulence is proposed according to the ARJ21 aerodynamic shape.The rolling moment coefficient,load increment,and altitude loss at different positions of the ARJ21 aircraft in the front aircraft wake turbulence field are calculated,and the most dangerous position for the rear aircraft to enter the front aircraft wake turbulence field is determined.The risk of encountering wake turbulence from an A330-200 heavy aircraft is evaluated under the current wake separation standards for the ARJ21,and the study demonstrates that there is still significant room for reducing the current wake separation standards.Finally,considering the influence of factors such as the reflection and diffusion of the front aircraft wake near the ground and its sinking in the atmosphere on the safety of the following aircraft,a model for calculating the hazard zone of the front aircraft wake was established,and the hazard zone caused by the wake of the A330-200 aircraft to the ARJ21 was calculated.Combining with the numerical simulation data,the evolution process of the hazard zone of the A330-200 wake in the section where the decision height is located over time was calculated,providing reference for dynamic wake spacing.By using the wake dissipation model,the hazard zone of the A330-200 wake in the final approach channel of the ARJ21 was calculated,and the minimum wake separation was determined based on the overlap between the front wake hazard zone and the final approach path of the following aircraft.The factors affecting wake separation safety in the final approach stage are explored and the strategies of wake separation reduction are put forward.The study indicates that ground effect can cause displacement and deformation of the wake vortex hazard zone,accelerating the detachment of the hazard zone from above the runway.When the wake vortex of leading aircraft sinks uniformly with the characteristic velocity,the minimum wake separation between ARJ21 and the heavy aircraft A330-200 during final approach is 2448 m,which is 26.32% of the current wake separation standard of 9.3km.This thesis aims to combine the study of the near-ground evolution of the front aircraft wake with the risk assessment of the following aircraft encountering the front wake vortex.A systematic and scientific method for reducing wake separation will be proposed to provide a theoretical basis for the formulation of dynamic and static wake separation standards for the domestically produced ARJ21 aircraft to follow the heavy A330 aircraft in the final approach,which has important theoretical research significance and practical application value.