Vortex Core Position Research Articles

Effects Of Wing Elasticity On Tip Vortex: 3D Deformation And 2D3C Flow Field Measurements

As aircraft embrace broader applications, the flexible wing presents a promising avenue to enhance aircraft performance across a wide range of flight conditions. Although the aerodynamic benefits of wing deformation are widely recognized, the present understanding of the tip vortex is relatively limited. This work experimentally examines the effects of wing deformation on the tip vortex of a simplified aircraft model with two kinds of elastic wings and a rigid wing. The 3D deformations and 2D3C flow fields are measured using a synchronous measurement system, which includes the high accuracy deformation measurement (HADM) method and the stereoscopic particle image velocimetry (SPIV). It is shown that increased wing elasticity leads to greater bending, with the wing tip moving along the streamwise, vertically upward, and spanwise inward directions. These deformations are closely linked to aerodynamic forces and influence the tip vortex positions. The more elastic wing, EW2, exhibits the highest vortex core position, more than 0.5 times the length of the wing root, while the other one, EW1, shows the strongest vortex in the lift-increased regime. In the early wakes, the tip vortex of the elastic wing is elongated along the spanwise direction, resulting in an asymmetric shape. As it convects downstream, the vortex core disperses via viscous diffusion, resulting in a relatively more circular shape with decreased vorticity.

Experimental investigation of the wake of tandem cylinders using pivoted flapping mechanism for piezoelectric flag

In this paper, the current of ocean at a depth with the velocity of 0.1–0.3 m/s has been studied. The effect of the mounting mechanism of the piezoelectric flag on the energy efficiency of the energy harvester is investigated. The flag is mounted uniquely, and the results are analyzed to explain the underlying mechanism associated with variations in power output. The experiments described extend our previous work and it is the experimental investigation of the baseline case for our previous work. It was found that using a pivoted mounting mechanism caused a significant improvement in flapping amplitude (51%) and dominant frequency (23%). The variation in the flag's distance from the bluff body (Gd) is also investigated. The maximum output for a passively mounted flag was obtained at Gd=2D due to the existence of a vortex core position at the same point where the flag's head was positioned. The same mechanism is implemented for tandem cylinder arrangement. The study found that increasing the distance between the bluff bodies resulted in the suppression of vortex shedding of the upstream cylinder by the rear cylinder. However, this behavior was found to be random and was thoroughly explored in this study. The obtained results were also verified through the flow visualization technique. A comparative analysis is made to show the optimal performance of the harvester by fine-tuning parameters such as the gap between cylinders and piezo flag, flow rate, and flag-mounting technique. The comparative analysis with benchmark cases demonstrated a rise in the A/L ratio by 30.25% and in the flapping frequency by 19.09% in the case of 120° cut C-shaped inverted cylinder upstream, indicating a higher percentage gain of 66% more energy harvesting. An increase of 51.18% in the A/L ratio and 22.79% in flapping frequency with the use of a pivot-mounted piezoelectric flag was observed, indicating higher energy harvesting performance compared to the baseline case (circular cylinder with fixed flag head).

Influence of gravitational tilt on the thermocapillary convection in a non-axisymmetric liquid bridge

Fluid slosh caused by residual acceleration in microgravity is a common problem encountered in space engineering. To solve this problem, the ground-based experiment research on the influence of gravity jitter and gravitational tilt on the thermocapillary convection (TCC) transition behaviour of non-axisymmetric liquid bridge has become an important issue in microgravity fluid management. Based on a mesoscale liquid bridge experimental platform which can realize gravitational tilt, the effect of gravitational tilt on TCC by using a high-speed camera equipped with a near-focus lens and a self-developed interface image recognition package. The results show that the spatio-temporal evolution of TCC by the influence of gravitational tilt is still divided into steady and oscillatory flow. In the stable TCC, the vortex core distortion of cellular flow caused by the imbalance left and right interface curvature invites cellular flow close to the free surface, and it shrinks to the intermediate height. As gravitational tilt increases, the transverse/longitudinal velocity peaks are significantly reduced, peak velocity has been reduced by 26%–27%. Meanwhile, the longitudinal velocity gradient at the free interface increases significantly. Therefore, gravitational tilt plays an important role in improving the surface flow velocity. In the oscillatory TCC, the position of vortex core is closer to the free interface at the hot/cold corner as the periodic mutual occupation of the left and right cellular flows. The TCC is obviously inhibited due to the gravitational tilt. The critical temperature difference is increased by 25% and the onset of temperature oscillation at the hot corner is delayed by 20% compared with conventional gravity condition.

Analysis of internal flow characteristics of squirrel-cage fan with multi-directional air intake impeller

The separate flow in the inlet region of the squirrel-cage fan, caused by airflow steering, hinders the further improvement of internal flow state and aerodynamic performance. This study proposes a multi-directional air intake design of the impeller to solve this problem. Specifically, a new parameter known as D* is introduced in this study to represent the axial air intake parameter of the impeller. Subsequently, the key parameters of the multi-directional air intake impeller (D*, entrance blade angle, exit blade angle) are optimally designed using an orthogonal experimental and CFD numerical simulation. These results are further validated through experimentation, demonstrating that a well-designed multi-directional air intake impeller can increase the fan's air volume, total pressure, and total efficiency by 27.3%, 12.6%, and 5.2%, respectively. Furthermore, it has been observed that the inclusion of an axial air intake in the impeller diminishes the impact of the entrance blade angle on fan efficiency. When evaluating different-sized models, the influence of the axial dimensionless parameter D* on the fan total efficiency shows a consistent pattern, which is worth noting that the efficiency does not necessarily increase with increasing values of D*, but rather the fan efficiency peaks when D* is approximately 0.5. The analysis of the flow field and entropy generation inside the fan reveal that the design can weaken the separation vortex at the inlet and shift the position of vortex core towards the impeller's leading edge, so as to eclectically enhance the uniformity of the impeller inlet and outlet, ultimately optimizing the aerodynamic characteristics within the fan. This study presents a novel approach to controlling the inlet separation flow of a squirrel-cage fan and provides a reference to elucidate the mechanism of internal flow evolution with the multi-directional air intake impeller.

On the simulation of a wing with detached end-plates using an actuator line based on an anisotropic Gaussian kernel

The results of an actuator line method (ALM) using an anisotropic Gaussian kernel for both, velocity sampling and force projection, are compared to the wall-resolved results of a NACA 0015 rectangular wing at an angle of attack of 10°. The rectangular wing is simulated both, with and without, detached end-plates to show that the ALM is capable of accounting for the presence of a narrow gap of 0.01 c between the tip of the wing and the end-plate. The anisotropic kernel shape is varied in the chordwise, thickness-wise, and spanwise directions for different grid sizes and number of actuating points. The body forces are truncated and regularized to enforce proper spacing between the actuating line and the end-plate. ALM and wall-resolved results are compared on the basis of the integrated lift and drag coefficients, the sectional lift and drag coefficients, as well as the tip vortex core size, position, and circulation. Recommendations are made regarding the optimal kernel shape for a given number of actuating points and mesh resolution.

Coupling-induced bistability in self-oscillating regimes of two coupled identical Spin-Torque Nano-oscillators

We consider a system of two coupled identical Spin Torque Nano-Oscillators (STNOs) with cylindrical geometry. The STNOs have free layers in the vortex magnetization configuration and fixed layer with magnetization in the out-of-plane direction. The magnetization dynamics in the two STNOs are analyzed by using a Thiele-like equation governing the dynamics of the vortex core positions. The coupling is assumed to be linear and symmetric and this enables to characterize it by a single complex parameter. We consider numerical simulations of the model as a function of the coupling strength k and phase ϕk. Depending on their values, different motions of the vortex cores are observed, e.g. periodic, and quasi-periodic. Each type of dynamics can be classified according to the symmetry property shown by the trajectories. In this respect, the transition between different types of motion corresponds to a symmetry-breaking process and we describe it as a bifurcation process. Fixing the value of the coupling constant phase, we found that there is a range of coupling constant strength in which the periodic and quasi-periodic motions coexist and both are stable. This bistability is an interesting phenomenon in connection to research on neuromorphic circuits based on STNOs.

U-net based vortex detection in Bose–Einstein condensates with automatic correction for manually mislabeled data

Quantum vortices in Bose–Einstein condensates (BECs) are essential phenomena in condensed matter physics, and precisely locating their positions, especially the vortex core, is a precondition for studying their properties. With the rise of machine learning, there is a possibility to expedite the localization process and provide accurate predictions. However, traditional machine learning requires particular considerable amount of manual data annotation, leading to uncontrollable accuracy. In this paper, we utilize the U-Net method to detect vortex positions accurately at the pixel level and propose an Automatic Correction Labeling (ACL) approach to optimize the acquisition of data sets for vortex localization in BECs. This approach addresses inaccuracies in the labeled vortex positions and improves the accuracy of vortex localization, especially the vortex core positions, while enhancing the tolerance for human mislabeling. The main process involves Rough Labeling →\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\rightarrow $$\\end{document} Machine Learning →\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\rightarrow $$\\end{document} Probability Region Search →\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\rightarrow $$\\end{document} Data Relabeling →\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\rightarrow $$\\end{document} Machine Learning again. The objective of ACL is to secure more accurate labeled data for model retraining. Through vortex localization experiments conducted in a two-dimensional Bose-Einstein condensate, our results establish the following: 1. Even under conditions of biased and missing manual annotations, U-Net can still accurately locate vortex positions; 2. Vortices exhibit certain regularities, and training U-Net with a small number of samples yields excellent predictive consequences; 3. The machine learning vortex locator based on the ACL method effectively corrects errors in manually annotated data, significantly improving the model’s performance metrics, thus enhancing the precision and metrics of vortex localization. This substantial advancement in the application of machine learning in vortex localization provides an effective way for vortex dynamics localization. Furthermore, this method of obtaining more accurate positions of approximate human labels through machine learning offers new insights for machine learning in other types of image recognition problems.

Long-wave deformation of in-ground-effect wake vortex under crosswind condition

The in-ground-effect (IGE) aircraft wake vortex poses great hazards to airplanes. Especially when the vortex column is deformed with a long wavelength, the vortex core position is harder to determine, and thus, the IGE wake vortex is essential to air traffic safety and requires more detailed research. In this study, to account for the effects of roll-up-induced structures, the wake vortex pair was initialized using the vortex sheet model proposed by Lin et al. [1]. The asymmetrical wing loading effect on IGE wake evolution was considered for the first time. The Large Eddy Simulation results showed that the crosswind strengthened the upwind vortex, while the long-term wake vortex evolution was not significantly influenced by the wind. Most importantly, in certain crosswind conditions, the wake vortex deformed sinusoidally and linked with its mirror counterpart. From a linear stability analysis, it was found that this long-wave deformation could only occur on the upwind side owing to the redistribution of the strain field caused by the near-ground wind shear. Due to secondary vortex generation, the deformation was suppressed and a low growth rate of α≈0.41 was recorded for the long-wave instability.

Large Eddy Simulation of Hydrofoil Tip Leakage Vortex

The axial-flow turbomachinery is important in water supply and drainage. However, there is a gap between the blade tip and the casing, which is easy to cause tip leakage vortex. Tip leakage of axial-flow turbomachinery has bad impact on the operation stability. In this case, the numerical simulation is used to study the simplified hydrofoil model with clearance. Then the change of tip leakage vortex core position and the pressure distribution are analyzed. Results show that with the fluid flows downstream, the longitudinal position of the tip leakage vortex core first drops and then rises. On different streamwise planes, the vortex core has the lowest pressure. From the downstream to the vortex generating position, the vortex core pressure decreases gradually, and the cavitation is most likely to occur at the location where the vortex occurs.

Experimental and Numerical Study of the Flow Field Structure of High-Speed Train with Different Nose Lengths Head at 15° Yaw

By using three different head types (5 m, 7.5 m and 10 m nose lengths), the CRH3 (China Railway High-speed 3) flow field structure at 15° yaw was studied through wind tunnel experiments and numerical simulations. The modifications of the aerodynamic coefficients were studied using the Improved Delayed Separation Eddy Simulation (IDDES) method. The results show that the longer the nose length of the tail car, the more it is affected by crosswind. However, the increase in turbulence mitigates the risk of overturning the tail car as the pressure distribution between the train side surface and the underbody becomes more disturbed. The nose length of the head car can affect the position and length of the longitudinal vortex core on the leeward side, thus affecting the lift and side force of each section of the train. The location of the time-averaged vortex core for a 15° crosswind is approximately 0.67H~0.7H high from the ground and 0.65H~0.67H wide from the center of the train. The main frequency of the leeward vortex ranges from 0.1 to 0.3. The transient vibration amplitude at the position of the vortex core is the largest, and the main frequency of vibration is 0.18. The tail car nose length should be properly lengthened since increasing the length of the tail car reduces the negative pressure on the surface of the tail car, thus reducing drag and side force. However, the excessive length of the tail car nose increases the risk of overturning under crosswind.

Investigation on conical separation vortex generated by swept shock wave/turbulent boundary layer interaction

To study the effects of Mach number, Reynolds number and deflection angle on the conical separation vortex generated by swept shock wave/turbulent boundary layer interaction , the experimental and numerical simulation methods are used. The Mach numbers are Ma=2.95 and Ma=4. The deflection angles are 12°, 15° and 18°. The incoming boundary layer thickness δ0.99 is 4.6 mm, 23 mm and 115 mm. The evolution characteristics of the vortex, including the vortex core position, the vortex area and the vortex intensity, and the effects of Mach number, Reynolds number and deflection angle on them are analyzed. The results show that the core trajectory of the vortex is distributed along the rear shock foot line of the λ shock structure. The Reynolds number is the main factor affecting the separation vortex core. The vortex area increases linearly along the direction of the inviscid shock, and the Reynolds number and the Mach number both are the factors affecting the growth rate of the separation vortex. The vortex intensity increases linearly along the direction of the inviscid shock. The vortex intensity is mainly affected by the Mach number and the deflection angle, but is not affected by the Reynolds number.

Conv-Wake: A Lightweight Framework for Aircraft Wake Recognition

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.

On the scaling of three-dimensional shock-induced separated flow due to protuberances

Supersonic flow over three-dimensional bodies protruding out of the turbulent boundary layer was investigated by means of experiments and numerical computations. A parametric study was performed by varying the shape and dimensions of the protuberance, as well as the freestream Mach numbers (1.5, 2, 2.5, 2.89, and 3.5). Surface streak line visualization, surface pressure measurements, and time-resolved Schlieren visualization were employed along with Reynolds-averaged Navier–Stokes computations to elicit the complex flow features such as the separation line, shock pattern, and the horseshoe vortex, which greatly influence the flow dynamics in the separated region. The rise in surface pressure at mid-span due to separation (plateau pressure) was dependent only on the incoming flow parameters and independent of protuberance geometry. The two-dimensional free interaction theory, applied for normal shock-induced separation, closely predicts the mid-span plateau pressure. Although protuberances are of varying shapes and dimensions, the inviscid bow shock (obtained from Euler computations) provided generalized scales, whose effects on shock boundary layer interactions are analyzed. The radius of curvature of the inviscid shock on the wall plane at the nose, which is theoretically related to the local second derivative (along the shock) of pressure jump, was found to be a determining parameter of mid-span separation length (Lsep). Since the spanwise distance of the sonic point on the inviscid shock was found to be strongly correlated with its nose radius of curvature, it follows that the “strong” portion of the inviscid bow shock fixes the mid-span separation location. These observations concerning mid-span plateau pressure, and the role of strong shock portion in fixing mid-span separation, suggest that the Lsep shall be predicted from a modification of the scaling laws for the length of plateau pressure region in two-dimensional shock boundary layer interaction, with the inclusion of a spanwise relieving effect. A correlation is obtained relating the Lsep with various incoming flow parameters and inviscid shock nose radius. The mid-span vortex core position was found to be linearly related to the Lsep. The radius of curvature of the separation shock is, however, found to be influenced by the entire inviscid shock, including the “weak” portion.

Ampere–Oersted field splitting of the nonlinear spin-torque vortex oscillator dynamics

We investigate the impact of the DC current-induced Ampère–Oersted field on the dynamics of a vortex based spin-torque nano-oscillator. In this study we compare micromagnetic simulations performed using mumax^3 and our analytical model based on the Thiele equation approach. The latter is improved by adding two important corrections to the Thiele equation approach. The first is related to the magneto-static contribution and depends on the aspect ratio of the magnetic dot. The second is a full analytical description of the Ampère–Oersted field contribution. The model describes quantitatively the simulation results in the resonant regime as well as the impact of the Ampère–Oersted field. Depending on the relative orientation between the vortex in-plane curling magnetisation (chirality) and the Ampère–Oersted field a strong splitting phenomenon appears in the fundamental properties (frequency and vortex core position) of the nano-oscillator. Thus, we show that the Ampère–Oersted field should not be neglected as it has a high impact on the spin-torque vortex oscillator dynamics.

Investigation of the wake flow of a simplified heavy vehicle with different aspect ratios

This study numerically investigates the effects of aspect ratios on the wake flow of a simplified ground transportation system (GTS) model using improved delayed detached-eddy simulation (IDDES) at a Reynolds number of 2.7 × 104. The aspect ratio Ra* ∈ [1.0, 2.0] is defined as the ratio of the height (H, variable) to the width (W, constant) of the GTS. The primary purpose of this work is to identify the relationship between the aspect ratio and the wake flow topology. The accuracy of the IDDES method has been validated by comparing the recirculation bubble configuration, vortex core position, velocity profiles, and aerodynamic drag of the baseline model (Ra* = 1.41) with those obtained from the previous large-eddy simulation study and the wind tunnel experiment. The results show that three typical flow states are observed in the near-wake region for various aspect-ratio cases. The aerodynamic drag increases by 4.60% and 2.06% for the aspect-ratio value equal to Ra* = 2.0 and Ra* = 1.8 (flow state II) and reduces by 6.75%, 7.37%, and 7.98% for the models with the aspect-ratio value of Ra* = 1.15, Ra* = 1.05, and Ra* = 1.0 (flow state III) compared to the aerodynamic drag of the baseline model with the aspect-ratio value of Ra* = 1.41 (flow state I). The dominant shedding frequency of the turbulent wake flow is identical for the aspect-ratio cases when the corresponding wake topology stays in the same flow state. The flow state acts as the substantial factor, which has an essential influence on the GTS's wake flow and its inducing aerodynamic response.

Dynamics of a Vortex Lattice in an Expanding Polariton Quantum Fluid.

If a quantum fluid is driven with enough angular momentum, at equilibrium the ground state of the system is given by a lattice of quantized vortices whose density is prescribed by the quantization of circulation. We report on the first experimental study of the Feynman-Onsager relation in a nonequilibrium polariton fluid, free to expand and rotate. Upon initially imprinting a lattice of vortices in the quantum fluid, we track the vortex core positions on picosecond timescales. We observe an accelerated stretching of the lattice and an outward bending of the linear trajectories of the vortices, due to the repulsive polariton interactions. Access to the full density and phase fields allows us to detect a small deviation from the Feynman-Onsager rule in terms of a transverse velocity component, due to the density gradient of the fluid envelope acting on the vortex lattice.

Electrical characterisation of higher order spin wave modes in vortex-based magnetic tunnel junctions

NiFe-based vortex spin-torque nano-oscillators (STNO) have been shown to be rich dynamic systems which can operate as efficient frequency generators and detectors, but with a limitation in frequency determined by the gyrotropic frequency, typically sub-GHz. In this report, we present a detailed analysis of the nature of the higher order spin wave modes which exist in the Super High Frequency range (3–30 GHz). This is achieved via micromagnetic simulations and electrical characterisation in magnetic tunnel junctions, both directly via the spin-diode effect and indirectly via the measurement of the coupling with the gyrotropic critical current. The excitation mechanism and spatial profile of the modes are shown to have a complex dependence on the vortex core position. Additionally, the inter-mode coupling between the fundamental gyrotropic mode and the higher order modes is shown to reduce or enhance the effective damping depending upon the sense of propagation of the confined spin wave.

Evaluation of the Effects of Actuator Line Force Smearing on Wind Turbines Near-Wake Development

In the present study, the effects of the actuator line force smearing on the predicted near-wake development of a model wind turbine are evaluated. To exclude the uncertainties related to the blade loads computation, the loads of a corresponding blade-resolving simulation are imposed. Three force projection functions are applied, which all radially scale with the local chord length: an isotropic Gauss force distribution, an anisotropic Gauss distribution with distinct projection widths in the chord and thickness directions, and a Gauss-Gumbel projection function which creates an airfoil-like force distribution in the chord direction. Comparisons with corresponding blade-resolving simulations and experimental results show a good agreement of the tip vortex core size, position and circulation. Comparison of the mid-wake instantaneous streamwise velocity with blade-resolving simulations shows a thinner vortex sheet and stronger effects of the trailed vortices in the actuator line simulation. Although the bound vortex shape scales with the projection function, no significant difference was observed in the resulting tip vortices and near-wake flow field between the three projection functions used. It is attributed to the similar projection width in the tip vortex region for all cases considered. With the chosen grid refinement in the tip vortex area and a smearing width that scales with the chord length, tip vortices that compare with high-resolution experiments and high-fidelity blade-resolving simulation could be generated with the actuator line approach.

On the numerical simulation of a confined cavitating tip leakage vortex under geometrical and operational uncertainties

The effects of operational and geometrical uncertainties on Tip Leakage Vortex (TLV) characteristics are investigated in the current research. Geometrical uncertainties are comprised of manufacturing tolerances or gradual geometry degradation over the time modeled by the Karhunen–Loève (KL) expansion. Operational uncertainties include randomness in operating temperature, inlet velocity, and pressure. These stochastic parameters are assumed to have a Beta probability distribution function with a standard deviation equal to measurement error. To perform Uncertainty Quantification (UQ) analysis, the non-intrusive polynomial chaos expansion is utilized. Moreover, Sobol’ indices obtain the contribution of each stochastic parameter on the quantity of interest. For numerical simulation of cavitating flow, the SST k−ω turbulence model and the Zwart mass transfer model were employed. It was observed that the cavitating tip leakage vortex flow as well as the lift and drag coefficients are profoundly affected by geometrical and operational uncertainties, which can also describe the discrepancies between numerical and experimental results. For instance, the deviation of vortices circulation, vortex core streamwise velocity, lift, and drag coefficients are more than 25%, 30%, 40%, and 70% of their mean value, respectively. Furthermore, results showed that the characteristics of TLV, like circulation and velocity field, are mostly influenced by operational uncertainties, while the vortex core position and viscous core radius are affected by geometrical randomness, specifically gap distance.

Two‐step locating method for aircraft wake vortices based on Gabor filter and velocity range distribution

Aircraft wake is a pair of strong counter-rotating vortices generated behind a flying aircraft, which might be dangerous to the following aircrafts. The real-time and precise locating of aircraft wake vortex-core positions is essential in the aviation safety field, especially in airport traffic management. This study proposes a two-step vortex-core locating method which uses the Gabor filter to make a preliminary locating and the velocity range distribution to make a fine locating consequently. The combination of Gabor filter and Doppler velocity distribution can improve the method's adaptability to complex background wind field and mitigate the impact of noise. Numerical examples and field detection campaigns from Changsha Huanghua International Airport and Hong Kong International Airport have well verified the good performance of the method, in terms of both accuracy and real time.