Aircraft Wake Turbulence Research Articles

Automatic recognition of airliners wake turbulence using various techniques of machine intelligence

Airplanes generate severe turbulent airflow, known as trailing vortices, which can have an adverse control impact on following airplanes. Aviation authorities worldwide impose separation standards between leading and following airplanes to reduce the capacity of airports to handle large volumes of traffic. Optimizing these separations is highly sought after. These separations are optimized based on several factors such as airplane size, weight, and design in addition to weather conditions. The recognition of trailing vortices is usually done manually through examination of pilot reports and analysis of flight data recorders (FDRs). This process can be subjective and depends greatly on the analyst's experience. Automated processes based on Artificial Intelligence (AI), such as Machine Learning (ML) and Computational Intelligence (CI), have shown a potential to better deal with such problems. Results obtained from these various techniques are presented to show their degree of appropriateness. Flight event identification, such as encounters with airplane vortices, wind shear, turbulence, and uncommanded control, can help establish aircraft warning and monitoring systems to enhance automatic flying, especially during landing and take-off. The developed model can attain great assurance recognition of the aircraft wake turbulence by supporting the air traffic controllers with the decision information in actual work to ensure aircraft safety. The success rates obtained from the investigated CI models compare favorably well to results obtained by either manual and/or other CI-based techniques when applied to vortex identification.

DBN-GABP model for estimation of aircraft wake vortex parameters using Lidar data

Aircraft wake turbulence is an inherent outcome of aircraft flight, presenting a substantial challenge to air traffic control, aviation safety and operational efficiency. Building upon data obtained from coherent Doppler Lidar detection, and combining Dynamic Bayesian Networks(DBN) with Genetic Algorithm-optimized Backpropagation Neural Networks(GA-BPNN), this paper proposes a model for the inversion of wake vortex parameters. During the wake vortex flow field simulation analysis, the wind and turbulent environment were initially superimposed onto the simulated wake velocity field. Subsequently, Lidar-detected echoes of the velocity field are simulated to obtain a data set similar to the actual situation for model training. In the case study validation, real measured data underwent preprocessing and were then input into the established model. This allowed us to construct the wake vortex characteristic parameter inversion model. The final results demonstrated that our model achieved parameter inversion with only minor errors. In a practical example, our model in this paper significantly reduced the mean square error of the inverted velocity field when compared to the traditional algorithm. This study holds significant promise for real-time monitoring of wake vortices at airports, and is proved a crucial step in developing wake vortex interval standards.

Research on wake interval of paired departure at closely spaced parallel runways

AbstractTo assess and improve the operation system of paired takeoff separation and reduce the risk of wake turbulence encounters during paired takeoff, a computational fluid dynamics (CFD) method is used to study the operational conditions and wake turbulence safety intervals of paired takeoff separation mode. Firstly, the safe area of wake turbulence under the paired takeoff separation mode is analyzed, and a safety interval model is constructed. Secondly, the SST k‐ω turbulence model is selected, and a numerical simulation method for the wake flow of the leading aircraft before the pairing is established based on CFD. Finally, a calculation method for the safety interval of paired takeoff separation is established. Taking Hongqiao Airport as an example, A320‐200 and B737‐800 are selected as the leading and trailing aircraft, and the wake flow field is simulated at 0, −1, and −2 m/s crosswind conditions. The simulation results are then used to analyze the operational conditions and safety intervals of paired takeoff separation mode. The results provide data support for the implementation of the paired takeoff separation mode and demonstrate the applicability of the CFD method in studying aircraft wake turbulence.

Aircraft rerouting and rescheduling in multi-airport terminal area under disturbed conditions

The disturbances, caused by resource competition, weather changes, and demand uncertainties, frequently occur and result in obvious fluctuations (e.g., the increase or decrease of demand and capacity) in demand and capacity. This work addresses the problem of aircraft rerouting and rescheduling in presence of disturbances, characterized by the increase or decrease of demand and capacity, at a multi-airport terminal maneuvering area (TMA). A multi-objective optimization model is proposed to minimize the total flight delays and total extra flying time, considering the aircraft wake turbulence separation, runway operation rules, air traffic control regulations, scheduling time windows, and airport/airspace capacity, etc. Based on the non-dominated sorting genetic algorithm (NSGA-II), we designed an efficient evolutionary algorithm to solve the proposed model and search the Pareto solutions. Five scenarios are designed to analyze and compare the operation performance under normal and disturbed conditions, using the classic First-Come-First-Served (FCFS) and optimized scheduling (OPTS) methods. A case study is conducted for Shanghai Pudong and Hongqiao Airports, and the computational results show that, compared with the FCFS method, the proposed OPTS method significantly performs a overall better performance in minimizing total flight delay and total extra flying time, while slightly inferior in optimizing the delay and extra flying time of one single flight.

Safety Evaluation of A380 Wake Turbulence Separation

CAAC (Civil Aviation Administration of China) set a standard on A380 wake turbulence separation right after China Southern Airlines brought in Airbus A380 in 2001.This paper considers from the possibility of the latter aircraft wake turbulence influencing the preceding one, which means the wake turbulence risk, makes safety evaluation on the wake turbulence separation standard of the preceding aircraft as A380, and the latter one as heavy type, medium type and light type, based on the safety target level that ICAO (International Civil Aviation Organization) authorized. Each type chooses a typical aircraft to calculate the possibility of influenced by the preceding wake turbulence corresponding with the standard under calm wind. The final result shows that the A380 wake turbulence separation standard setting by CAAC is safe.

Strategy for Attending Takeoffs and Landings to Reduce the Aircraft Operating Costs and the Passenger Delays

The objective of this research was to establish and evaluate a strategy for attending to the takeoffs and landings at congested airports, in order to reduce aircraft operating costs and passenger delay times. The continuous growth of air transport activity has created congestion at many major airports worldwide. As a consequence, aircraft must often remain in waiting lines before they could be attended onto the runways for takeoff or landing. This in turn increases the aircraft operating costs and passenger discomfort. In the strategy proposed the traditional rule for attending to aircraft, on a first-come-first-served basis, was substituted with a sequence that reduces operating costs and passenger delays. The order of attention given to each aircraft was obtained using a heuristic algorithm that did not require enumeration of all the possible sequences. Consequently, the solution could be obtained in a short time. Results when using this strategy showed that significant reductions of up to 47.6% in operating costs and 73.2% in passenger delays could be achieved. The main contribution of this paper is the establishment of a strategy that makes possible these savings. The amount of benefits achieved depends on the proportion of aircraft wake turbulence classes that operate in a given airport. In general, the largest benefits are obtained when there is a mixture of different classes and when they are in a proportion of 40% small and 60% heavy. By utilizing the strategy proposed herein it is possible to obtain significant benefits for both airlines and passengers.

W202 仙台空港における後方乱気流シミュレーション(WS2-1 CFDとEFDの融合研究,ワークショップ2)

Numerical simulation of aircraft's wake turbulence was carried out by integrating LIDAR measurements at Sendai Airport. Four-dimensional variational (4D-VAR) method was applied to integrate LIDAR measurements into three-dimensional large eddy simulation (LES). The behavior of the simulated wake turbulence was interactively analyzed through an immersive virtual environment. The CFD simulation of wake turbulence was also performed by employing numerical weather model as the initial and boundary conditions. By placing virtual wake vortices in the initial condition, the rapid decay process of wake turbulence was observed under the horizontal roll convection currents in sea breeze.

604 離陸航空機の後流渦のライダ計測融合シミュレーション(J01-1 流体情報学と協調的可視化(1),ジョイントセッション,21世紀地球環境革命の機械工学:人・マイクロナノ・エネルギー・環境)

Numerical simulation of aircraft's wake turbulence was carried out by integrating lidar measurements. Four-dimensional variational method (4D-Var) was applied to integrate the lidar measurements into three-dimensional large eddy simulation (LES). This paper describes the results using lidar measurements at Sendai airport.

Dynamic Behavior of an Aircraft Encountering Aircraft Wake Turbulence

This paper deals with the dynamic behavior of an airplane encountering aircraft wake turbulence. A digital computer simulation was developed to study the response of an aircraft flying into a trailing vortex wake. The simulation includes the complete six degree-of-freedom equations of motion, a description of the vortex velocity field, unsteady aerodynamics, and pilot control input. The parameters, varied in this simulation, include the penetration angle, separation distance, aircraft size (for both the penetrating and generating aircraft), and pilot control input (single-or multi-axes). Predicted vortex induced motions are presented for several probe aircraft. The probe aircraft selected are representative of general aviation, business, and light jet transport type aircraft, whereas the aircraft used to generate the vortex wakes are representative of the commercial transport fleet. The computer predictions indicate that relatively large aircraft (80,000 Ib jet transport) can experience unacceptable vortex induced roll excursions. In addition to evaluating the vortex induced responses, the effect of pilot control input was assessed. It was found that pilot control input could be momentarily out of phase with the vortex induced disturbance. Thus, in certain cases, the pilot's control input would tend to aggravate the vortex-induced upset.

Aircraft Wake Turbulence and its Detection Eds: John H. Olsen, Arnold Goldberg and Milton Rogers Proceedings of a Symposium, Seattle, September 1970. 602 pp. Illustrated. £13.80.

Aircraft Wake Turbulence and its Detection Eds: John H. Olsen, Arnold Goldberg and Milton Rogers Proceedings of a Symposium, Seattle, September 1970. 602 pp. Illustrated. £13.80.

Aircraft Wake Turbulence Avoidance

AIRCRAFT WAKE TURBULENCE AVOIDANCEMr. William A. McGowanNASA Headquarters, Washington, D.C., U.S.A.SUMMARY Aircraft trailing vortex systems are made up oftwo counter-rotating cylindrical air masses, about a wing spanapart, extending aft along the flight path. Vortex systems oflarge aircraft contain winds which can be hazardous to otheraircraft encountering them in flight. The greatest hazardpotentials exist in areas where aircraft of a wide range ofclasses are operating (e.g., light utility/observation andheavy transport/bomber).Results of analytical studies and flight tests are used todescribe the formation and severity of trailing vortices and thespatial extent of their influence. This information is thenused to outline procedures for ready application by pilots,tower operators, and others concerned with the flow of traffic.The procedures provide the necessary appreciation of thephysical attributes of trailing vortices, the potential hazardsinvolved when encountering them, and how best to avoid thedangerous portions of the wake during flight operations.NASA has a comprehensive research effort underway to betterdescribe aircraft trailing vortex behavior and concurrently,other studies are aimed at the development of a concept eitherto discourage initial formation of high intensity vortices or toencourage early dissipation of the dangerous wake, through air-craft design.INTRODUCTION Trailing vortex systems, or the wake turbu-lence, of large transport type aircraft are known to have windsof hazardous intensities if encountered in flight by other air-craft (1-7). An additional troublesome aspect of the problem isthat the vortices which are generally difficult to detect behindthe large aircraft persist for quite some time after generation.The wake turbulence of most concern to pilots is caused by thetrailing vortex system generated by the wing lift of large,heavy aircraft.Past theoretical studies and flight tests were concernedwith the extent of vortex system movement and intensity toimprove our understanding and acquaint aircraft operators with