Journal articles: 'Aircraft wake'

1

Pan, Weijun, Yuanfei Leng, Haoran Yin, and Xiaolei Zhang. "Identification of Aircraft Wake Vortex Based on VGGNet." Wireless Communications and Mobile Computing 2022 (June 18, 2022): 1–10. http://dx.doi.org/10.1155/2022/1487854.

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The exploration of information for aircraft wake vortex enables us to obtain new knowledge of wake turbulence separation standards. Traditional manual methods cannot work satisfactorily for the identification of great number of wake vortex data with high accuracy. Fortunately, the LiDAR intensity data can be explained by integrating LiDAR products with the strategies of computer vision. To overcome the limitation of traditional manual methods, this paper is aimed at developing an automatic method to identify a given set of wake vortices from various aircrafts. The main innovation works are outlined as follows. (1) From the wake vortex data that consists of various aircrafts measured by Wind3D 6000 LiDAR, a grayscale dataset of wake flow is constructed to boost the deep learning model for identifying aircraft wake vortex. (2) Following this, we propose a new method for the identification of aircraft wake vortex by modifying the VGG16 network, providing binary classifications of uncertain behavior patterns for wake vortices. To evaluate the proposed identification model, performance evaluation was conducted on our dataset, where experimental results revealed the values of 0.984, 0.951, 0.959, and 0.955 in terms of accuracy, precision, recall, and F1-score, respectively.

2

Pan, Weijun, Zhengyuan Wu, and Xiaolei Zhang. "Identification of Aircraft Wake Vortex Based on SVM." Mathematical Problems in Engineering 2020 (May 12, 2020): 1–8. http://dx.doi.org/10.1155/2020/9314164.

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The aircraft wake vortex has important influence on the operation of the airspace utilization ratio. Particularly, the identification of aircraft wake vortex using the pulsed Doppler lidar characteristics provides a new knowledge of wake turbulence separation standards. This paper develops an efficient pattern recognition-based method for identifying the aircraft wake vortex measured with the pulsed Doppler lidar. The proposed method is outlined in two stages. (i) First, a classification model based on support vector machine (SVM) is introduced to extract the radial velocity features in the wind fields by combining the environmental parameters. (ii) Then, grid search and cross-validation based on soft margin SVM with kernel tricks are employed to identify the aircraft wake vortex, using the test dataset. The dataset includes wake vortices of various aircrafts collected at the Chengdu Shuangliu International Airport from Aug 16, 2018, to Oct 10, 2018. The experimental results on dataset show that the proposed method can identify the aircraft wake vortex with only a small loss, which ensures the satisfactory robustness in detection performance.

3

Filippov, R. N., and E. A. Titova. "Effect of the Wake Vortex on the Mutual Safety of Winged Aircraft Following the Same Route." Proceedings of Higher Educational Institutions. Маchine Building, no. 10 (739) (October 2021): 65–73. http://dx.doi.org/10.18698/0536-1044-2021-10-65-73.

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The wake vortex consists mainly of two vortices, which are formed when the stream flows around the wings of an aircraft. A semi-empirical model of a stable vortex wake is proposed and analyzed. The model allows describing the velocity field in a vortex, depending on the characteristics of the aircraft generator, as well as assessing the effect of the vortex on the subsequent aircraft. Statistical modeling was carried out to determine the safe interval between the aircrafts for the characteristic sections of the trajectory. When moving over the sea, a straight-line route, a trajectory with turns and an ascent to an altitude for flying around the island were chosen; on the land section of the movement, a flight over the relief was simulated. A significant influence of the ruggedness of the relief on the probability of an aircraft falling when it enters a wake vortex is shown. The effect of the displacement of the aircraft trajectories in the vertical and horizontal planes and the increase in the average flight speed on the safe interval between the aircrafts is investigated.

4

Tomaszewski, Jessica M., Julie K. Lundquist, Matthew J. Churchfield, and Patrick J. Moriarty. "Do wind turbines pose roll hazards to light aircraft?" Wind Energy Science 3, no. 2 (November 2, 2018): 833–43. http://dx.doi.org/10.5194/wes-3-833-2018.

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Abstract. Wind energy accounted for 5.6 % of all electricity generation in the United States in 2016. Much of this development has occurred in rural locations, where open spaces favorable for harnessing wind also serve general aviation airports. As such, nearly 40 % of all United States wind turbines exist within 10 km of a small airport. Wind turbines generate electricity by extracting momentum from the atmosphere, creating downwind wakes characterized by wind-speed deficits and increased turbulence. Recently, the concern that turbine wakes pose hazards for small aircraft has been used to limit wind-farm development. Herein, we assess roll hazards to small aircraft using large-eddy simulations (LES) of a utility-scale turbine wake. Wind-generated lift forces and subsequent rolling moments are calculated for hypothetical aircraft transecting the wake in various orientations. Stably and neutrally stratified cases are explored, with the stable case presenting a possible worst-case scenario due to longer-persisting wakes permitted by lower ambient turbulence. In both cases, only 0.001 % of rolling moments experienced by hypothetical aircraft during down-wake and cross-wake transects lead to an increased risk of rolling.

5

Whitehouse, G. R., and R. E. Brown. "Modelling a helicopter rotor’s response to wake encounters." Aeronautical Journal 108, no. 1079 (January 2004): 15–26. http://dx.doi.org/10.1017/s0001924000004954.

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In recent years, various strategies for the concurrent operation of fixed-and rotary-wing aircraft have been proposed as a means of increasing airport capacity. Some of these strategies will increase the likelihood of encounters with the wakes of aircraft operating nearby. Several studies now exist where numerical simulations have been used to assess the impact of encounters with the wakes of large transport aircraft on the safety of helicopter operations under such conditions. This paper contrasts the predictions of several commonly-used numerical simulation techniques when each is used to model the dynamics of a helicopter rotor during the same idealised wake encounter. In most previous studies the mutually-induced distortion of the wakes of the rotor and the interacting aircraft has been neglected, yielding the so-called ‘frozen vortex’ assumption. This assumption is shown to be valid only when the helicopter encounters the aircraft wake at high forward speed. At the low forward speeds most relevant to near-airfield operations, however, injudicious use of the frozen vortex assumption may lead to significant errors in predicting the severity of a helicopter’s response to a wake encounter.

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Pan, Weijun, Yuming Luo, Shuai Han, and Hao Wang. "Large Eddy Simulation Research on the Evolution Mechanism of Aircraft Wake Influenced by Cubic Obstacle." Geofluids 2022 (June 24, 2022): 1–17. http://dx.doi.org/10.1155/2022/1324531.

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Aircraft wake is a kind of intense air movement, and the study of its generation, development, and dissipation law is of great significance to the flight safety. There are abundant researches on the evolution of aircraft wakes affected by weather and ground effects; however, there are few studies on the influence of a single obstacle on the evolution of aircraft wake. In this article, in order to explore the influence of a single obstacle on the evolution of aircraft wake, firstly, we develop a computational fluid dynamics-based method of simulation of aircraft wake affected by cubic obstacle of different heights in order to obtain the wake intensity changes and position changes before and after being affected by the obstacle. Then, the result data are visualized and analyzed, and we obtain the results of velocity and Q criterion contours, circulation, and data related to wake vortex structure. CFD simulations are conducted, including the cases of the vertical distance between wake vortex and obstacle which is 20 m, 60 m, 100 m, and no obstacle. The quantitative results indicate that a single obstacle also has a great influence on the evolution of the wake vortex. Obstacle will shorten the time for the wake vortex to enter the fast decay stage, and the smaller the distance the wake vortex is above the obstacle, the faster it enters the fast decay stage. In the same time, the circulation will reduce 20% more under the same calculation time when the wake is 20 m above the obstacle than when the wake is 100 m above the obstacle, and the circulation will reduce 45% more than when there is no obstacle. Single obstacle also leads to the generation of multiple secondary vortices and rotates around the wake vortex, resulting in the increase of wake vortex core radius, wake vortex core spacing, and wake vortex height.

7

Pan, Weijun, Zirui Yin, Yuming Luo, Anding Wang, and Yuanjing Huang. "Dynamic Aircraft Wake Separation Based on Velocity Change." Aerospace 9, no. 11 (October 22, 2022): 633. http://dx.doi.org/10.3390/aerospace9110633.

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Traditional research on static wake-vortex reduction usually considers only the influence of external environmental factors, while ignoring the dynamic change in an aircraft’s flight state. In order to solve this problem, this paper proposes a method to reduce separation using dynamic wake information based on changes in flight velocity. Firstly, relying on the wake-vortex generation and dissipation model, the initial circulations and dissipation parameters of the wake vortex at different aircraft velocities are calculated. Then, the complete evolution process of the wake vortex generated by different types of aircraft at different velocities is analyzed, and the evolution law of a wake vortex with changing velocity is obtained. Afterwards, according to the actual aerodynamic shape of CRJ-900, the aerodynamic model for CRJ-900 when it encounters a wake vortex is established. The situation of an CRJ-900 encountering a wake vortex under TBS is analyzed, which proves that TBS is safe and has a certain reduction potential. Then, taking the rolling moment coefficient as the safety index, the minimum safe separations at different velocities are calculated. Finally, a simulation for the separation reduction based on a dynamic wake vortex is carried out. Compared with the static wake-based separation, the dynamic wake-based separation technology can greatly reduce the aircraft separation requirements while ensuring the operation safety. The final simulation results show that the dynamic separation reduction in CRJ-900 following a medium and heavy aircraft can reach 44.3% and 51.6%, respectively.

8

Pan, Wei-Jun, Yuan-Fei Leng, Tian-Yi Wu, Ya-Xing Xu, and Xiao-Lei Zhang. "Conv-Wake: A Lightweight Framework for Aircraft Wake Recognition." Journal of Sensors 2022 (July 15, 2022): 1–11. http://dx.doi.org/10.1155/2022/3050507.

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The recognition of aircraft wake vortex can provide an indicator of early warning for civil aviation transportation safety. In this paper, several wake vortex recognition models based on deep learning and traditional machine learning were presented. Nonetheless, these models are not completely suitable owing to their dependence on the visualization of LiDAR data that yields the information loss of in reconstructing the behavior patterns of wake vortex. To tackle this problem, we proposed a lightweight deep learning framework to recognize aircraft wake vortex in the wind field of Shenzhen Baoan Airport’s arrival and departure routes. The nature of the introduced model is geared towards three aspects. First, the dilation patch embedding module is used as the input representation of the framework, attaining additional rich semantics information over long distances while maintaining parameters. Second, we combined a separable convolution module with a hybrid attention mechanism, increasing the model’s attention to the space position of wake vortex core. Third, environmental factors that affect the vortex behavior of the aircraft’s wake were encoded into the model. Experiments were conducted on a Doppler LiDAR acquisition dataset to validate the effectiveness of the proposed model. The results show that the proposed network has an accuracy of 0.9963 and a recognition speed at 100 frames per second was achieved on an experimental device with 0.51 M parameters.

9

Ma, Yuzhao, Jiangbei Zhao, Haoran Han, Pak-wai Chan, and Xinglong Xiong. "Aircraft Wake Recognition Based on Improved ParNet Convolutional Neural Network." Applied Sciences 13, no. 6 (March 10, 2023): 3560. http://dx.doi.org/10.3390/app13063560.

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The occurrence of wake can pose a threat to the flight safety of aircraft and affect the runway capacity and airport operation efficiency. To effectively identify aircraft wake, this paper proposes a novel convolutional neural network (CNN) method of aircraft wake recognition based on the improved parallel network (ParNet). Depthwise separable convolution (DSC) was introduced into the ParNet to make the wake recognition model lightweight. In addition, the convolutional block attention module (CBAM) was introduced into the wake recognition model to improve the capacity of the model to extract the spatial features of the wind field. The proposed aircraft wake recognition method was used to identify the aircraft wake based on the lidar wind field scanning image of Hong Kong International Airport. The best wake recognition effect was obtained with a recognition accuracy of 98.91% and an F1 value of 98.90%. As the number of parameters of the model was only 0.46 M, the aircraft wake could be identified on an ordinary computer. Thus, the proposed method can effectively identify aircraft wake.

10

Gerz, Thomas, Frank Holzäpfel, and Denis Darracq. "Commercial aircraft wake vortices." Progress in Aerospace Sciences 38, no. 3 (April 2002): 181–208. http://dx.doi.org/10.1016/s0376-0421(02)00004-0.

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11

Roa, Julio, Antonio Trani, Junqi Hu, and Navid Mirmohammadsadeghi. "Simulation of Runway Operations with Application of Dynamic Wake Separations to Study Runway Limitations." Transportation Research Record: Journal of the Transportation Research Board 2674, no. 12 (October 1, 2020): 199–211. http://dx.doi.org/10.1177/0361198120953152.

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This paper presents an evaluation of runway operations at Chicago O’Hare International Airport to estimate the impact of proposed wake vortex separation including Recategorization Phase II and III dynamic separations. The evaluation uses a Monte Carlo simulation model that considers arrival and departure operations. The simulation accounts for static and dynamic wake vortex separations, aircraft fleet mix, runway occupancy times, aircraft approach speeds, aircraft wake circulation capacity, environmental conditions, and operational error buffers. Airport data considered for this analysis are based on Airport Surface Detection Equipment Model X records from Chicago O’Hare International Airport from January to November 2016. Dynamic wake separations are tailored to each unique set of conditions by using environmental and aircraft performance parameters as input and allowing aircraft to be exposed to the same wake vortex strength as in Recategorization Phase II (RECAT II). The analysis shows that further reductions beyond RECAT II for aircraft pairs separated by 2 nautical miles or less is not operationally feasible. These wake separations already result in little to no wake dependency. When this is the case, the challenges in wake separation are to meet runway occupancy times and to make sure aircraft separations allow for human operational variations without resulting in aircraft turnarounds or double-aircraft-occupancy runway violations.

12

Golovnev, I. G., V. V. Vyshinsky, A. I. Zhelannikov, and K. V. Lapshin. "DESIGN CONCEPTS OF AN ONBOARD EARLY WARNING SYSTEM OF PILOT ABOUT ENTERING WAKE VORTICES FROM ANOTHER AIRCRAFT." Civil Aviation High TECHNOLOGIES 21, no. 4 (August 28, 2018): 84–95. http://dx.doi.org/10.26467/2079-0619-2018-21-4-84-95.

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An airborne aircraft forms a wake vortex behind itself dangerous for other entering it aircraft both piloted and unmanned. Wake vortex intensity depends on parameters of the aircraft creating it, so the greater the aircraft mass is, the higher its impact on other aircraft is. It is not possible to register visually the wake vortex, since in fact it is invisible. Introduction of wide-body aircraft like A380 into service leads to the revision of separation rules with the aim to increase admissible distance between aircraft. There is a quite demonstrative case when Challenger 604 got into the wake vortex after A380: though separation rules at the altitude were observed, Challenger performed an out-of-control rotating descent from the altitude of 10000 m to 3000 m. At present, in spite of multi-year research there are no real verified suggestions on wake vortex safety of aircraft flights. The paper presents the methodological basis and design concepts of an onboard early warning system of a pilot about entering wake vortices from another aircraft. The main task of the proposed system is to reveal wake vortices according to pressure decrease in their cores; to do it we perform on-line measuring of pressure in front of an aircraft. Measurements are done by a standard onboard air data system and an onboard inertial satellite system in order to control the consistency of “barometric” altitude readings and those of altitude defined by an inertial satellite system. The value of wake vortices rarefaction measured by an onboard air data system allows estimating the influence degree of wake vortices on the aircraft roll moment with the help of a special hardware and software complex and to determine the necessity to change the flight mode. It is proposed to use a missile bench for the dimensioning wake vortices on aircraft models in order to test computational methods of wake vortices dimensioning

13

Joshi, Arnav, Mustafa M. Rahman, and Jean-Pierre Hickey. "Recent Advances in Passive Acoustic Localization Methods via Aircraft and Wake Vortex Aeroacoustics." Fluids 7, no. 7 (June 29, 2022): 218. http://dx.doi.org/10.3390/fluids7070218.

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Passive acoustic aircraft and wake localization methods rely on the noise emission from aircraft and their wakes for detection, tracking, and characterization. This paper takes a holistic approach to passive acoustic methods and first presents a systematic bibliographic review of aeroacoustic noise of aircraft and drones, followed by a summary of sound generation of wing tip vortices. The propagation of the sound through the atmosphere is then summarized. Passive acoustic localization techniques utilize an array of microphones along with the known character of the aeroacoustic noise source to determine the characteristics of the aircraft or its wake. This paper summarizes the current state of knowledge of acoustic localization with an emphasis on beamforming and machine learning techniques. This review brings together the fields of aeroacoustics and acoustic-based detection the advance the passive acoustic localization techniques in aerospace.

14

Xu, Peimin, Yueyue Yang, Jie Zhou, and Guiyu Zhou. "Aerodynamic Characteristic Analysis of V-22 Tilt-Rotor Aircraft in Hover." Journal of Physics: Conference Series 2280, no. 1 (June 1, 2022): 012020. http://dx.doi.org/10.1088/1742-6596/2280/1/012020.

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Abstract Tilt-rotor aircraft combines the vertical take-off and landing function of helicopters with the high-speed cruise function of fixed-wing aircraft, which has given rise to extensive attention in the aviation field, but the complex aerodynamic characteristics of the rotor flow field and the interference of rotor/fuselage have always been tough problems. In recent years, the continuous development of high-performance computer and the combination of high-precision CFD method and dynamic overset grid technology, make it possible to perform fine numerical simulation of tilt-rotor aircraft’s flow field. In this paper, the low-dissipation fifth-order Roe-WENO scheme and overset grid method are used to solve the unsteady N-S equation, and the hovering state of tilt-rotor aircraft is numerically simulated. The result shows: under the interference of ground effect and fountain effect, the lift coefficient of blade when the azimuth angle is 180° to 360° is obviously smaller than that when the azimuth angle is 0° to 180°. The vortex structure of the hovering flow field of V-22 tilt-rotor aircraft is mainly composed of the fountain effect recirculation zone, the tip vortex wake and the root vortex wake. The tip vortex wake develops downwards, shrinks inward and approaches the fuselage. After the root wake falls off, it converges and fuses on the surface of nacelles. The root vortex wake is strong and moves towards the front of the fuselage and the plane of symmetry.

15

Wang, Hexiang, Junqiang Wu, Qiuting Guo, Guangyuan Liu, Jifei Wu, Dawei Liu, Yang Tao, and Neng Xiong. "Study on the Influence of a Powered Nacelle on the Wake Vortex Characteristics of Wide-Body Aircraft." Aerospace 11, no. 6 (June 4, 2024): 452. http://dx.doi.org/10.3390/aerospace11060452.

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The aircraft wake vortex is an important factor affecting flight safety; as an important part of the aircraft, the powered nacelle will inevitably have an important impact on the aircraft wake vortex, so it is of great practical significance to research it. The present study focused on the numerical simulation of the wake flow of large aircraft (as the front aircraft) and the comparative analysis of the influence of engine jets on the wake flow. In order to meet the accuracy requirements and control the consumption of computing resources, LES and RANS methods were compared, and the RANS method was finally selected for subsequent calculation. The dynamic effect of jet flow was simulated by simplifying the boundary conditions of the inlet fan and outlet bypass as the mass flow boundary condition. The simulation results showed that the engine nacelle will have a significant impact on the morphology of the aircraft wake flow (position and strength of the main vortex in the wake flow system), which is caused by the vortices formed under the shear flow and separated flow of the nacelle. However, the nacelle will not significantly change the total strength of the wake vortex (half-plane circulation). The engine jet intensity causes additional turbulent mixing, which will accelerate the fusion of the nacelle vortex and ultimately change the intensity ratio of the inner wing vortex and the wingtip vortex, affecting the trajectory of the wake of the mean vortex. The study provides a corresponding reference for the following research on a wake vortex by a powered nacelle.

16

Kong, Jian Guo. "Safety Evaluation of A380 Wake Turbulence Separation." Applied Mechanics and Materials 278-280 (January 2013): 31–34. http://dx.doi.org/10.4028/www.scientific.net/amm.278-280.31.

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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.

17

Luo, Haotian, Weijun Pan, Yidi Wang, and Yuming Luo. "A330-300 Wake Encounter by ARJ21 Aircraft." Aerospace 11, no. 2 (February 8, 2024): 144. http://dx.doi.org/10.3390/aerospace11020144.

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Today, aviation has grown significantly in importance. However, the challenge of flight delays has become increasingly severe due to the need for safe separation between aircraft to mitigate wake turbulence effects. The primary emphasis of this investigation resides in elucidating the evolutionary attributes of wake vortices in homogeneous isotropy turbulence. The large eddy simulation (LES) method is used to scrutinize the dynamic evolution of wake vortices engendered by an A333 aircraft in the atmospheric milieu and assess its ramifications on the ARJ21 aircraft. The research endeavor commences by formulating an LES methodology for the evolution of aircraft wake vortices, integrating adaptive grid technology to reduce the necessary grid volume significantly. This approach enables the implementation of axial and non-axial grid adaptive refinement, leading to more accurate simulations of both axial and non-axial vortices. Numerical simulations are conducted using the LES approach to scrutinize three distinct rates of turbulence dissipation amidst the ambient atmospheric turbulence, and the results are juxtaposed with Lidar measurements (Wind3D 6000 LiDAR) of wake vortices acquired at Chengdu Shuangliu International Airport (CTU). Subsequently, the rolling moment of the following aircraft is calculated, and three-dimensional hazard zones are determined for the A333. It is found that during the approach phase, the wake turbulence separation minima for an ARJ21 (CAT-F) following an A333 (CAT-B) is 3.35 NM, which represents a reduction of approximately 33% compared to ICAO RECAT (Wake Turbulence Re-categorization). The findings validate the dependability of the fine-grained mesh used in the vortex core region, engendered through the adaptive grid method, which proficiently captures the Crow instability and the interconnected phenomena of vortices in the numerical examination of aircraft wake. The safety of wake encounters primarily depends on the magnitude of environmental turbulence and the development of structural instability in wake vortices.

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Pan, Wei Jun, and Jia Yu Li. "Flight Separation Research Based on the Aircraft Wake." Applied Mechanics and Materials 253-255 (December 2012): 2201–7. http://dx.doi.org/10.4028/www.scientific.net/amm.253-255.2201.

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Improving airspace and runway utilization is the key to reducing flight delays with the rapid development of the air transport industry. Current flight separation standards generally take excessive interval margin, resulting in unnecessary waste of airspace resources and runway resources. Wake accidents still happended even with strictly wake separation standards compliance, which is mainly due to the imperfect separation standards affected by the wake complexity and modeling imperfections. Refering to Chinese and international main wake models, we propose to improve the existing wake standard, usage of modern wake separation systems and dynamic wake detection strategy with automated judgment method. Purpose is reducing flight delays and improving the utilization of the airspace and runway on the basis of keeping safety.

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Pan, Weijun, Jingkai Wang, Yaxing Xu, Qianlan Jiang, and Yuming Luo. "Approach and Landing Aircraft Wake Encounter Risk Based on Reynolds-Averaged Navier-Stokes Numerical Simulation." International Journal of Aerospace Engineering 2022 (September 5, 2022): 1–24. http://dx.doi.org/10.1155/2022/9126755.

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In order to shorten the wake safe separation, numerical simulation technology with aerodynamic response models and strip models have been combined to calculate wake hazard zone. As a realistic case, a medium aircraft ARJ21 following a heavy aircraft A330-200 is considered, and the Reynolds-averaged Navier-Stokes (RANS) method is used to explore the wake vortex evolution process of the leading aircraft at the decision height. A strip algorithm is proposed to calculate the rolling moment coefficient and overload increment of the ARJ21 after encountering the wake of the front aircraft in the three-dimensional space. The proposed algorithm identifies the area where the wake of the front aircraft can cause risks to the following aircraft and analyzes the evolution process of the hazard zone of the section where the decision height is located. The minimum safe separation of the ARJ21 following the A330-200 is 1.32 nmile, which is 26.4% of the ICAO separation standard of 5 nmile. When the average runway occupancy time (ROT) is reduced to match the separation of 1.32 nmile, the capacity of runway 02R/20L in Tianfu International Airport could theoretically reach 102.37 sorties/h under this aircraft pair combination. Compared to original 27 sorties/h, the runway capacity can be improved up to 279.14%, which will increase the airport operation efficiency.

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Shariff, Karim. "Making Aircraft Vortices Visible to Radar by Spraying Water into the Wake." Journal of Atmospheric and Oceanic Technology 33, no. 12 (December 2016): 2615–38. http://dx.doi.org/10.1175/jtech-d-16-0066.1.

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AbstractAircraft trailing vortices pose a danger to following aircraft during takeoff and landing. This necessitates spacing rules, based on aircraft type, to be enforced during approach in instrument flight regulation (IFR) conditions; this can limit airport capacity. To help choose aircraft spacing based on the actual location and strength of the wake, it is proposed that wake vortices can be detected using conventional ground-based precipitation and cloud radars. This is enabled by spraying a small quantity of water into the wake from near the wing. The vortex strength is revealed by the Doppler velocity of the droplets. In the present work, droplet size distributions produced by nozzles used for aerial spraying are considered. Droplet trajectory and evaporation in the flow field is numerically calculated for a heavy aircraft, followed by an evaluation of radar reflectivity at 6 nautical miles (n mi) behind the aircraft. Small droplets evaporate, while larger droplets fall out of the wake. In the humid conditions that typically prevail during IFR, a sufficient number of droplets remain in the wake and give good signal-to-noise ratios (SNR). For conditions of average humidity, higher-frequency radars combined with spectral processing give good SNR.

21

Campos, L. M. B. C., and J. M. G. Marques. "On the compensation and damping of roll induced by wake vortices." Aeronautical Journal 118, no. 1207 (September 2014): 1039–61. http://dx.doi.org/10.1017/s0001924000009738.

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Abstract The effect of the wake of a leading aircraft on a following aircraft is demonstrated by calculating the rolling motion consisting of three terms: (i) the free rolling motion due to initial bank angle and roll rate; (ii) the forced wake response due the rolling moment induced by the wake encounter; (iii) the forced control response due to aileron deflection to counter the wake vortex effects. It is shown that in the absence of control action, the roll rate of the following aircraft goes through a peak, and then decays, leading to a constant asymptotic bank angle; the latter is a measure of the magnitude of the wake effect, e.g. is larger for weaker damping. The exact analytical solution of the roll equation appears as a power series of a damping factor, whose coefficients are exponential integrals of time; it is shown that the first two terms give an accuracy better than 2%. The theory is used to simulate 15 combinations of wake vortex encounters between leading and following aircraft in the five ICAO/FAA weight categories: light, medium, heavy, special (B757) and very large (A380).

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Ivanov, S. V. "Spectroscopic detection of aircraft wake gases." Physics of Wave Phenomena 15, no. 1 (March 2007): 57–65. http://dx.doi.org/10.3103/s1541308x07010049.

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Hemati, Maziar S., Jeff D. Eldredge, and Jason L. Speyer. "Wake Sensing for Aircraft Formation Flight." Journal of Guidance, Control, and Dynamics 37, no. 2 (March 2014): 513–24. http://dx.doi.org/10.2514/1.61114.

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Breitsamter, C. "Wake vortex characteristics of transport aircraft." Progress in Aerospace Sciences 47, no. 2 (February 2011): 89–134. http://dx.doi.org/10.1016/j.paerosci.2010.09.002.

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Pan, Weijun, Yanqiang Jiang, and Yuqin Zhang. "Simulation Study of the Effect of Atmospheric Stratification on Aircraft Wake Vortex Encounter." Sustainability 15, no. 8 (April 8, 2023): 6391. http://dx.doi.org/10.3390/su15086391.

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The atmospheric environment is an important factor affecting aircraft wake vortex decay and wake separation. In this paper, numerical calculations and strip modeling are combined to complete an analysis of wake encounter under three atmospheric stratifications expressed in Brunt–Väisälä (BV) frequencies. The SST k-ω turbulence model was chosen for the numerical simulation to complete the evolution of the wake vortex field of the A330 aircraft. The A320 and ERJ190 were selected as the aircraft for wake encounter analysis. The dimensionless roll moment coefficient (RMC) was selected as the indicator to construct a three-dimensional hazard zone for wake encounters and then calculate the wake separation. The results show that the higher BV frequencies correspond to faster wake vortex decay and hazard zone dissipation, and a slower decrease in the height of the hazard zone. The risk level of the ERJ190 is higher than that of the A320 with the same wake intensity, and the wake separation of the A320 following the A330 is 5516 m, which is 25.5% less than the ICAO RECAT separation standard, while the wake separation of the A330 following the ERJ190 is 5803 m, which is 37.6% less than the ICAO RECAT separation standard.

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Grubišić, Vanda, Johannes Sachsperger, and Rui M. A. Caldeira. "Atmospheric Wake of Madeira: First Aerial Observations and Numerical Simulations." Journal of the Atmospheric Sciences 72, no. 12 (November 24, 2015): 4755–76. http://dx.doi.org/10.1175/jas-d-14-0251.1.

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Abstract The island of Madeira is well known for giving rise to atmospheric wakes. Strong and unsteady atmospheric wakes, resembling a von Kármán vortex street, are frequently observed in satellite images leeward of Madeira, especially during summer months, when conditions favoring the formation of atmospheric wakes occur frequently under the influence of the Azores high. Reported here is the analysis of the first airborne measurements of Madeira’s wake collected during the 2010 Island-induced Wake (I-WAKE) campaign. High-resolution in situ and remote sensing data were collected in the I-WAKE by a research aircraft. The measurements reveal distinctive wake signatures, including strong lateral wind shear zones and warm and dry eddies downwind of the island. A strong anticorrelation of the horizontal wind speed and sea surface temperature (SST) was found within the wake. High-resolution numerical simulations with the Weather Research and Forecasting (WRF) Model were used to study the dynamics of the wake generation and its temporal evolution. The comparison of the model results and observations reveals a remarkable fidelity of the simulated wake features within the marine boundary layer (MBL). Strong potential vorticity (PV) anomalies were found in the simulated MBL wake, emanating from the flanks of the island. The response of the wake formation within the MBL to surface friction and enhanced thermal forcing is explored through the model sensitivity analyses.

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Shen, Chun, Jianbing Li, and Hang Gao. "Two Parameter-Retrieval Algorithms of Aircraft Wake Vortex with Doppler Lidar in Clear Air." EPJ Web of Conferences 237 (2020): 08024. http://dx.doi.org/10.1051/epjconf/202023708024.

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Aircraft wake is a pair of strong counter-rotating vortices generated behind an aircraft, which might be very hazardous to a flowing aircraft and the detection of which has attracted much attention in aviation safety field. This conference paper introduces two parameter-retrieval algorithms, i.e., Optimization method and Max-min method. They have been integrated into a toolbox and can retrieve the parameters of wake vortex efficiently and robustly.

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Zhelannikov, A. I. "Features of vortex trace propagation for aircraft with propellers." Civil Aviation High Technologies 26, no. 3 (June 23, 2023): 103–13. http://dx.doi.org/10.26467/2079-0619-2023-26-3-103-113.

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The article presents the results of a study of the characteristics of the wake vortex of aircraft with turboprop engines. Using the example of the An-12 aircraft, it is shown that rotating propellers make a noticeable contribution to the propagation of the vortex trail behind the aircraft. This is proved by some studies, as well as numerous observations. It also describes a technique for studying the wake vortex of aircraft with propellers. The method is based on the method of discrete vortices. The relevance of such studies is due to the growing interest of carrier companies in aircraft with turboprop engines. It has been proven that when transporting passengers and cargo on such vessels over distances of 700–800 km, maintenance and fuel costs are reduced by about 30–40%. Therefore, the fleet of turboprop aircraft, such as An-22, An-70, An-12, as well as Tu-95, Il-38, C-130, etc., has been preserved so far. New turboprop aircraft are being developed and put into operation: A-400M, Il-114, Il-112M. The vortex trail behind such aircraft also poses a danger to other aircraft flying behind. A feature of the propagation of the wake vortex behind aircraft with propellers is the interaction of vortices coming off the airframe and vortices from the propellers. As a result, due to the rotation of all the screws in one direction, symmetry is broken in the propagation of vortices descending from the right and left halves of the wing. Therefore, it is important to understand how differently the vortices that descend from the airframe of an aircraft with turboprop engines behave. For the convenience of the study, the method of accounting for the effect of vortices from screws is integrated into a special calculation and software package, also based on the method of discrete vortices. In it, when calculating the characteristics of the wake vortex, the flight weight, speed and altitude of the aircraft, its flight configuration, atmospheric conditions, proximity of the earth, axial velocity in the core of the vortex and some other factors are taken into account. This complex has passed the necessary testing and state registration. A number of measures were carried out to validate and verify the developed complex, confirming the operability of the programs included in it and the reliability of the results obtained from it. The results of the study of the characteristics of the wake vortex behind the Antonov-12 aircraft in the form of vertical velocity spectra and fields of perturbed velocities at various distances from it are presented. It is shown that propellers noticeably affect the propagation of the wake vortex behind turboprop aircraft. This circumstance must be taken into account by the crews of aircraft flying behind such aircraft.

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Campos, L. M. B. C., and J. M. G. Marques. "On an analytical model of wake vortex separation of aircraft." Aeronautical Journal 120, no. 1232 (August 30, 2016): 1534–65. http://dx.doi.org/10.1017/aer.2016.89.

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ABSTRACTA theory is presented on the effect of wake turbulence of a leading aircraft on the roll stability of a following aircraft, leading to a simple formula for the safe separation distance between the two aircraft that provides estimates of aircraft separation distances comparable to existing empirical regulations, based on experience. The formula includes the effects of flight and atmospheric conditions, and the characteristics of the leading and following aircraft; it applies to similar or dissimilar aircraft, and it indicates the parameters and conditions leading to increasing or decreasing separation. The formula is applied not only to the three International Civil Aviation Organization (ICAO) categories of aircraft (light, medium and heavy, respectively, Cessna Citation, B737 and B747) but also to ‘special’ aircraft requiring larger separation distance (Boeing 757) and to the world’s largest airliner (Airbus A380).

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Rossow, Vernon J. "Wake hazard alleviation associated with roll oscillations of wake-generating aircraft." Journal of Aircraft 23, no. 6 (June 1986): 484–91. http://dx.doi.org/10.2514/3.45333.

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Rubin, William L. "The Generation and Detection of Sound Emitted by Aircraft Wake Vortices in Ground Effect." Journal of Atmospheric and Oceanic Technology 22, no. 5 (May 1, 2005): 543–54. http://dx.doi.org/10.1175/jtech1718.1.

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Abstract Sound recorded by the author in March 2002 at JFK International Airport shows that wake vortices in ground effect emit infrasound that is 1) more than 40 dB stronger than audible wake vortex sound; 2) substantially stronger than the infrasound component of wind noise and airport noise; and 3) comparable to, and often stronger than, the infrasound component of aircraft noise. Spectra and time plots of the magnitude of wake-vortex-generated sound are presented for aircraft landing on JFK runway 31R.

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Gayet, J. F., V. Shcherbakov, C. Voigt, U. Schumann, D. Schäuble, P. Jessberger, A. Petzold, et al. "The evolution of microphysical and optical properties of an A380 contrail in the vortex phase." Atmospheric Chemistry and Physics 12, no. 14 (July 26, 2012): 6629–43. http://dx.doi.org/10.5194/acp-12-6629-2012.

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Abstract. A contrail from a large-body A380 aircraft at cruise in the humid upper troposphere has been probed with in-situ instruments onboard the DLR research aircraft Falcon. The contrail was sampled during 700 s measurement time at contrail ages of about 1–4 min. The contrail was in the vortex regime during which the primary wake vortices were sinking 270 m below the A380 flight level while the secondary wake remained above. Contrail properties were sampled separately in the primary wake at 90 and 115 s contrail age and nearly continously in the secondary wake at contrail ages from 70 s to 220 s. The scattering phase functions of the contrail particles were measured with a polar nephelometer. The asymmetry parameter derived from these data is used to distinguish between quasi-spherical and aspherical ice particles. In the primary wake, quasi-spherical ice particles were found with concentrations up to 160 cm−3, mean effective diameter Deff of 3.7 μm, maximum extinction of 7.0 km−1, and ice water content (IWC) of 3 mg m−3 at slightly ice-subsaturated conditions. The secondary and primary wakes were separated by an almost particle-free wake vortex gap. The secondary wake contained clearly aspherical contrail ice particles with mean Deff of 4.8 μm, mean (maximum) concentration, extinction, and IWC of 80 (350) cm−3, 1.6 (5.0) km−1, and 2.5 (10) mg m−3, respectively, at conditions apparently above ice-saturation. The asymmetry parameter in the secondary wake decreased with contrail age from 0.87 to 0.80 on average indicating a preferential aspherical ice crystal growth. A retrieval of ice particle habit and size with an inversion code shows that the number fraction of aspherical ice crystals increased from 2% initially to 56% at 4 min contrail age. The observed crystal size and habit differences in the primary and secondary wakes of an up to 4 min old contrail are of interest for understanding ice crystal growth in contrails and their climate impact. Aspherical contrail ice particles cause less radiative forcing than spherical ones.

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Liu, Zhongxun, Nicolas Jeannin, Francois Vincent, and Xuesong Wang. "Modeling the Radar Signature of Raindrops in Aircraft Wake Vortices." Journal of Atmospheric and Oceanic Technology 30, no. 3 (March 1, 2013): 470–84. http://dx.doi.org/10.1175/jtech-d-11-00220.1.

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Abstract The present work is dedicated to the modeling and simulation of the radar signature of raindrops within wake vortices. This is achieved through the computation of the equation of raindrop motion within the wake vortex flow. Based on the inhomogeneous distribution of raindrops within wake vortices, the radar echo model is computed for raindrops in a given resolution cell. Simulated Doppler radar signatures of raindrops within wake vortices are shown to be a potential criterion for identifying wake vortex hazards in air traffic control. The dependence of the radar signature on various parameters, including the radial resolution and antenna elevation angle, is also analyzed.

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He, Xin, Yilong Ma, Hong Yang, and Yaqing Chen. "Modeling and Simulation of Wake Safety Interval for Paired Approach Based on CFD." Journal of Advanced Transportation 2021 (December 30, 2021): 1–10. http://dx.doi.org/10.1155/2021/7891475.

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In order to relieve the stress caused by the surge of flight flow, Closely Spaced Parallel Runways (CSPRs) have been built in many hub airports, and a paired approach mode has been applied to CSPRs in some countries. This paper proposes a method for optimizing the wake separation between aircrafts which utilizes a paired approach, aiming at reducing longitudinal separation by using computational fluid dynamics technology. Firstly, the model of the wake vortex field of the paired lead aircraft is constructed. Secondly, the numerical simulation preparation for the characteristics of the wake vortex field is completed through the computational pretreatment of the model. Thirdly, a calculation model of wake safety interval based on paired approach operation is established. Finally, the proposed method shows its superiority comparing with other methods. This method realized visual analysis of wake vortex through optimization modeling based on computational fluid dynamics, contributing to increasing the capacity of the runway and improving the operation efficiency of an aerodrome.

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Rojas, Jose I., Marc Melgosa, and Xavier Prats. "Sensitivity Analysis of Maximum Circulation of Wake Vortex Encountered by En-Route Aircraft." Aerospace 8, no. 7 (July 16, 2021): 194. http://dx.doi.org/10.3390/aerospace8070194.

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Wake vortex encounters (WVE) can pose significant hazard for en-route aircraft. We studied the sensitivity of wake vortex (WV) circulation and decay to aircraft mass, altitude, velocity, density, time of catastrophic wake demise event, eddy dissipation rate, wing span, span-wise load factor, and WV core radius. Then, a tool was developed to compute circulations of WV generated/encountered by aircraft en-route, while disregarding unrealistic operational conditions. A comprehensive study is presented for most aircraft in the Base of Aircraft Data version 4.1 for different masses, altitudes, speeds, and separation values between generator and follower aircraft. The maximum WV circulation corresponds to A380-861 as generator: 864 and 840 m2/s at horizontal separation of 3 and 5 NM, respectively. In cruise environment, these WV may descend 1000 ft in 2.6 min and 2000 ft in 6.2 min, while retaining 74% and 49% of their initial strength, respectively. The maximum circulation of WV encountered by aircraft at horizontal separation of 3 NM from an A380-861 is 593, 726, and 745 m2/s, at FL200, FL300, and FL395, respectively. At 5 NM, the circulations decrease down to 578, 708, and 726 m2/s. Our results allow reducing WVE simulations only to critical scenarios, and thus perform more efficient test programs for computing aircraft upsets en-route.

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Bobylev, Anatoliy V., Victor V. Vyshinsky, George G. Soudakov, and Vassiliy A. Yaroshevsky. "Aircraft Vortex Wake and Flight Safety Problems." Journal of Aircraft 47, no. 2 (March 2010): 663–74. http://dx.doi.org/10.2514/1.46432.

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Wang, Y., M. White, and G. N. Barakos. "Wind-Turbine Wake Encounter by Light Aircraft." Journal of Aircraft 54, no. 1 (January 2017): 367–70. http://dx.doi.org/10.2514/1.c033870.

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Sarpkaya, Turgut. "Decay of Wake Vortices of Large Aircraft." AIAA Journal 36, no. 9 (September 1998): 1671–79. http://dx.doi.org/10.2514/2.570.

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Rodenhiser, Rebecca J., William W. Durgin, and Hamid Johari. "Ultrasonic Method for Aircraft Wake Vortex Detection." Journal of Aircraft 44, no. 3 (May 2007): 726–32. http://dx.doi.org/10.2514/1.25060.

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Weijun, Pan, Duan Yingjie, Zhang Qiang, Tang Jiahao, and Zhou Jun. "Deep Learning for Aircraft Wake Vortex Identification." IOP Conference Series: Materials Science and Engineering 685 (November 22, 2019): 012015. http://dx.doi.org/10.1088/1757-899x/685/1/012015.

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Rubin, William L. "Radar–Acoustic Detection of Aircraft Wake Vortices." Journal of Atmospheric and Oceanic Technology 17, no. 8 (August 2000): 1058–65. http://dx.doi.org/10.1175/1520-0426(2000)017<1058:radoaw>2.0.co;2.

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Chernyshev, S. L., A. M. Gaifullin, and Yu N. Sviridenko. "Civil aircraft vortex wake. TsAGI׳s research activities." Progress in Aerospace Sciences 71 (November 2014): 150–66. http://dx.doi.org/10.1016/j.paerosci.2014.06.004.

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Sarpkaya, Turgut. "Decay of wake vortices of large aircraft." AIAA Journal 36 (January 1998): 1671–79. http://dx.doi.org/10.2514/3.14021.

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Jacquin, L., D. Fabre, D. Sipp, V. Theofilis, and H. Vollmers. "Instability and unsteadiness of aircraft wake vortices." Aerospace Science and Technology 7, no. 8 (December 2003): 577–93. http://dx.doi.org/10.1016/j.ast.2003.06.001.

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Holzäpfel, Frank, Michael Frech, Thomas Gerz, Arnold Tafferner, Klaus-Uwe Hahn, Carsten Schwarz, Hans-Dieter Joos, et al. "Aircraft wake vortex scenarios simulation package – WakeScene." Aerospace Science and Technology 13, no. 1 (January 2009): 1–11. http://dx.doi.org/10.1016/j.ast.2007.09.008.

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HolzÃ¤pfel, Frank, Thomas Gerz, and Robert Baumann. "Aircraft wake vortices â prediction and mitigation." PAMM 7, no. 1 (December 2007): 1100801–2. http://dx.doi.org/10.1002/pamm.200700569.

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Vechtel, D. "In-flight simulation of wake encounters using deformed vortices." Aeronautical Journal 117, no. 1196 (October 2013): 997–1018. http://dx.doi.org/10.1017/s0001924000008654.

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Abstract During the decay process the shape of wake vortices changes significantly which has an influence on the encounter characteristics, hence on the encounter hazard. In order to evaluate the influence of vortex deformation on the wake encounter hazard, in-flight simulations with the DLR research aircraft ATTAS were carried out. For a realistic analysis of wake encounters flow fields of matured vortices were generated with large eddy simulations. These flow fields were used for the determination of histories of induced forces and moments acting on the wake encountering aircraft. The force and moment histories were then fed into the equations of motions of the non-linear six degree-of-freedom in-flight simulation of the DLR research aircraft ATTAS. In order to compare different stages of vortex deformation, encounters were simulated in flight with wavy vortices and vortex rings. The most important benefit of the in-flight-simulation is the realistic environment, which enables a realistic assessment of pilots’ encounter acceptance. The analysed scenario was of a wake encounter during final approach. The encounter conditions correspond to separation distances of about 4nm and 5nm behind an aircraft of the ‘heavy’ category. During the encounters the ATTAS was flown under manual control. Altogether 31 encounters were simulated in flight, 9 with wavy vortices and 22 with vortex rings.

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Yin, Hai Tao, Xin Min Wang, Wen Chao Li, and Rong Xie. "Study of Disturbances Model on Carrier-Based Aircraft Landing Process." Applied Mechanics and Materials 321-324 (June 2013): 824–28. http://dx.doi.org/10.4028/www.scientific.net/amm.321-324.824.

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The disturbances in the landing process of carrier-based aircraft include deck movement and ship wake. To guarantee the security of landing process, the simulation and model are necessary for the disturbances, and the deck movement and ship wake should be analyzed as well. On the basis of analysis of disturbances, the disturbances can be catalogued into two types: deck movement and ship wake. Combining with the relevant instructions in the American Army Standard, the mathematical model of each disturbance is established. The simulations of the deck movement and ship wake are also shown in this paper, which can supply the reliable disturbances models for the design of the control system of carrier-aircraft landing process.

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Seredyn, Tomasz, Adam Dziubiński, and Piotr Jaśkowski. "CFD Analysis of the Fluid Particles Distribution by Means of Aviation Technique." Transactions on Aerospace Research 2018, no. 1 (March 1, 2018): 67–97. http://dx.doi.org/10.2478/tar-2018-0006.

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Abstract The article describes a computational study, using CFD models, of droplet spray dispersal in the wake of a ‘Turbo Kruk’ airplane up to 500 m downstream. The CFD Reynolds-averaged Navier-Stokes (RANS) models use a Lagrangian (droplet phase) and Eulerian (fluid phase) procedure to predict the droplet trajectories trough the turbulent aircraft wake. The methods described in the work have the potential to improve current models for aerial spraying and will help in the development of new spraying procedures. In this study, the CFD models are used to describe the phenomenon of sprays released from atomizers mounted on the plane. A parametric study of the aircraft model examines the effects of crosswind on the aircraft’s vortex structures and the resulting droplet trajectories. The study shows, that such influence is underestimated in the current models. A comparison of the present results to AGDISP predictions is provided.

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He, Xin, Rui Zhao, Haoran Gao, Changjiang Yuan, and Jingyi Wang. "Prediction of Aircraft Wake Vortices under Various Crosswind Velocities Based on Convolutional Neural Networks." Sustainability 15, no. 18 (September 7, 2023): 13383. http://dx.doi.org/10.3390/su151813383.

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In order to overcome the time-consuming computational drawback of using computational fluid dynamics (CFD) for the numerical simulation of aircraft wake vortex evolution under different crosswind velocities, this paper proposes a wake vortex prediction model based on a convolutional neural network (CNN) algorithm. The study focuses on the B737-800 aircraft, and employs CFD numerical simulations to obtain the evolutionary characteristics of wake vortex parameters under crosswind velocities ranging from 0 to 7 m/s. The wake vortex velocity and Q-criterion vorticity values are collected and partitioned into mutually exclusive training and testing datasets. A CNN model is constructed, and the training dataset is used to tune hyperparameters to minimize loss and achieve accurate predictions. After saving the trained model, the desired crosswind velocity value is input to obtain the predicted wake vortex velocity and Q-criterion vorticity values. The results indicate that the convolutional neural network model exhibits an average absolute percentage error of 1.5%, which is 2.3% lower than that of the fully connected neural network model. This suggests that convolutional neural networks can enhance the accuracy of wake vortex predictions, as demonstrated in this study. Compared to traditional CFD methods, the proposed model reduces the computation time by approximately 40 times, effectively improving computational efficiency and offering valuable insight for studies involving numerous numerical simulations, such as analyzing the safety separation between aircraft wake vortices during paired approach procedures.

Journal articles on the topic 'Aircraft wake'

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