Effect Of Wind Gusts Research Articles

Aeroacoustic analysis of fixed- and variable-pitch controlled multirotors and noise reduction via rotor phase control

This research conducts a comparative analysis of the aerodynamic and aeroacoustic characteristics of fixed-pitch and variable-pitch controlled multirotors (i.e., revolution per minute and collective pitch control). The study encompasses hovering and forward flight conditions, considering wind gust effects. Specifically, high-resolution time-frequency analysis is conducted to investigate the interference and modulation effects of multirotor noise. The analysis reveals significant variations in spectral characteristics depending on the control method. Notably, the frequencies of tonal noise from variable-pitch controlled multirotor do not exhibit short-periodic modulation, in contrast to those of fixed-pitch controlled multirotor. Considering the distinctive spectral characteristics of variable-pitch controlled multirotor, this study explores the effectiveness of noise reduction in variable-pitch controlled multirotor by implementing rotor phase control methods. To validate the noise reduction in time series simulations, a deep learning model is employed to determine the dynamically optimized rotor phases. A multilayer perceptron neural network was trained to derive the optimal rotor phase angles over time, considering the target observer points and flight conditions. The results demonstrate a substantial reduction in noise at the target observer points.

SoftWind: Software-defined trajectory correction modelling of gust wind effects on internet of drone things using glowworm swarm optimization

The dynamic nature of the atmosphere, especially wind gust, poses a crucial challenge to efficient and real-time drone operations. This article presents a novel MQTT based software-defined drone network for trajectory correction of drone flights in gusty wind conditions using Glowworm Swarm Optimization (GSO). By imposing the GSO to the software-defined drone network, our proposed model SoftWind has optimized the navigation and control capabilities of drones by correcting the trajectories in a gusty wind environment. We have analyzed the trajectories and convergence of drones due to wind gusts. As wind disturbances affect the trajectories of drones, we have corrected it by our trajectory correction model and evaluated the direction of the drones must fly to mitigate the wind gust and the resultant velocity compared to the no-wind environment. This study analyzed the trajectories of 100 drone flights due to various wind gust lengths (i.e., 40 m, 10 m, 6 m, and 3 m) for a fixed gust amplitude of 15 m/s and various gust amplitude (i.e., 0 m/s, 5 m/s, 15 m/s, and 40 m/s) for a fixed gust length 5 m. We observed that all the drones are converged to a single point due to low gust length (≤ 5 m) and high gust amplitude (≥ 35 m/s). It is also found that the direction of the drone must fly 28.87°. East of South to mitigate the effect of wind gusts having 10 m gust length and 15 m/s gust amplitude and the resultant velocity of the drone is 22.38 m/s. The result shows that SoftWind reduces the convergence time by 26 %-54 % as compared to other existing models.

A Study on Directly Interconnected Offshore Wind Systems during Wind Gust Conditions

An investigation of the effects of wind gusts on the directly interconnected wind generators is reported, and techniques toward the mitigation of the wind gust negative influences have been proposed. Using a directly interconnected system approach, wind turbine generators are connected to a single synchronous bus or collection grid without the use of power converters on each turbine. This bus can then be transformed for transmission onshore using High Voltage Alternating Current, Low-Frequency Alternating Current or High Voltage Direct Current techniques with shared power conversion resources onshore connecting the farm to the grid. Analysis of the potential for instability in transient conditions on the wind farm, for example, caused by wind gusts is the subject of this paper. Gust magnitude and rise time/fall time are investigated. Using pitch control and the natural damping of the high inertial offshore system, satisfactory overall system performance and stability can be achieved during these periods of transience.

Aerodynamic characteristics of an aerostat under unsteady wind gust conditions

An analysis of the effect of wind gusts on the aerodynamic characteristics of an aerostat is presented in this study. A three dimensional computational fluid dynamics based flow analysis of an aerostat using the realizable k−ϵ model is presented. The performance of the aerostat is analyzed by varying the angle of attack, gust amplitude, gust duration, gust velocity profile and the aerostat shape. Actual wind data is used to formulate the gust parameters used for the study. It is found that the aerostat drag is unaffected by the angle of attack because of the streamlined structure. A trade-off between the drag and lift values suggests the use of a slight positive angle of attack for the stable operation of the aerostat. A gust with a short rising or falling time with small amplitude is severe than the symmetric gust with larger amplitude and a slower rising or falling profile. A scaling methodology for the aerodynamic characteristics of the aerostat for different angles of attack, gust amplitudes, gust duration and aerostat shapes is presented. The scaling obtained for different angles of attack and gust amplitudes is linear, whereas for different gust duration the scaling is not linear.

Development of a Cargo Airdrop Modeling Method for a Tactical Blended-Wing-Body UAV

In this paper, the development of a cargo airdrop modeling method is presented for a fixed-wing tactical UAV. The UAV, which is being developed in the framework of the DELAER UAS project, is based on the Blended-Wing-Body layout, and its mission is to deliver cargo and lifesaving supplies via airdrop, to remote and isolated Greek territories as well as over isolated islands in the Aegean Sea. At first, a simplified kinematic model is developed, to describe the trajectory of the cargo. Then, the critical airdrop parameters, such as the aerodynamic drag and the effect of wind gusts, are identified and incorporated to the model. Based on this model, an analysis methodology is proposed, conducted in several simulation loops. In each simulation loop, the cargo mass, release height, drop velocity and wind gust speed are the main variables. The results are given in a form of scatter plots, depicting the simulated cargo airdrop positions on the ground (or sea), around an actual target location, with respect to the drop height, drop velocity and wing magnitude. A solid conclusion is that, by releasing the cargo box with tailwind, the accuracy of the airdrop can be improved as much as 67% compared to any other wind direction.

Математичне моделювання впливу шквального вітру на технічні та рослинні структури на урбанізованих територіях

Stormy events in recent years have shown that the destructive effects of wind on urban technical structures and plants pose a special threat. The paper provides an overview of mathematical models and approaches to experimental and theoretical studies of the problems associated with the effects of wind gusts and tornadoes on urban areas. Computer simulations of wind action on standard multistorey buildings in Ukraine are given. The coefficients of normal and shear components of forces and moments of forces acting on the surface of buildings, as well as vortex tracks over the residential complex at different wind speeds from moderate to severe have been computed. The calculations were performed by the finite element method using the model of turbulent air flow in the package AnSys2020. It is shown how with the help of a slight change in shape (roofs, additional passages, shields) the destructive effects of wind on the buildings and plants, as well as the threat to human life can be reduced.

МНОГОСЕНСОРНАЯ БЕСПРОВОДНАЯ СЕТЕВАЯ СИСТЕМА ДЛЯ МОНИТОРИНГА УРАГАНОВ

A wireless sensor system is described. Pressure sensor measurements are compared with National Weather Service data and wind tunnel test data. It then describes a minivan highway test that was used to evaluate the effect of sensor housing shape on pressure measurements. Computational Fluid Dynamics (CFD) analysis was also performed to complement the wind tunnel and road van tests, as well as to determine optimal mesh shapes and sizes, boundary conditions, and the best turbulence model that would reproduce the measured pressures. (UV) The following describes the Hurricane Simulator tests that were used to evaluate the effect of wind gusts on pressure and automatic/cross-correlations of pressure and velocity between different sensors. A CFD simulation of the UF Hurricane Simulator test was also performed to evaluate the sensitivity of turbulence models in capturing true pressure and velocity changes on the test site due to gusts. Vibration testing using a shaker table to analyze the effect of structural vibration on sensor pressure measurements is described.

A coupled HDG-FV scheme for the simulation of transient inviscid compressible flows

A methodology that combines the advantages of the vertex-centred finite volume (FV) method and high-order hybridisable discontinuous Galerkin (HDG) method is presented for the simulation of the transient inviscid two dimensional flows. The resulting method is suitable for simulating the transient effects on coarse meshes that are suitable to perform steady simulations with traditional low-order methods. In the vicinity of the aerodynamic shapes, FVs are used whereas in regions where the size of the element is too large for finite volumes to provide an accurate answer, the high-order HDG approach is employed with a non-uniform degree of approximation. The proposed method circumvents the need to produce tailored meshes for transient simulations, as required in a low-order context, and also the need to produce high-order curvilinear meshes, as required by high-order methods. Numerical examples are used to test the optimal convergence properties of the combined HDG-FV scheme and to demonstrate its potential in the context of simulating the wind gust effect on aerodynamic shapes.

Istraživanje njihanja izazvanog iznenadnim opterećenjem vetrom pri korišćenju vazdušnih merdevina

In Hungary, as in other countries around the world, intervention firefighting units often use a mechanically operated aerial ladder for high-altitude rescue tasks. The safe operation of the equipment is only possible under strict safety regulations and requires a high level of expertise from the operating staff. During each intervention, extraordinary events such as sudden wind gusts can occur, which can cause extreme overload of the structural members of aerial ladders and have adverse effects on the equipment that can lead to malfunctions and - even worse - to accidents. Therefore it is important to study the consequences of external influences on aerial ladders during operation. The examination was performed on a widely used Magirus M32-L aerial ladder. The reason for choosing this type of aerial ladder is because it has a wide operating range, therefore test results can be a good starting point for other similar equipment as well. In this paper the development of our beam model and the performed finite element simulations are presented. The aim of the research is to develop a model based on geometrical measurement data that is suitable for studying the effects of wind gusts on the ladder structure. With our research, we aim to contribute to the safe operation of aerial ladders and to prevent possible accidents.

Development of Efficient Dynamic Aeroelasticity Model for High Fidelity Pointing Accuracy Assessment of VLBI Earth-Based Radio Antennas

Modern Earth-based radio antennas of very-long-baseline interferometry system are furnished with robust control systems for their pointing control. Their pointing accuracy is critical to the quality of the radio wave-front captured. External disturbances, particularly those of wind gusts, produce a non-negligible dynamic aeroelastic response that degrades its pointing accuracy, and yet are not mitigated by the antenna’s control system. In this paper, a high fidelity and efficient dynamic aeroelastic model of an earth-based antenna is developed which is used to study the effects of wind gusts on the antenna’s pointing accuracy. Model order reduction of the antenna structural model is carried out using Craig–Bampton method taking into consideration the dominant modal characteristics of the antenna. The aerodynamic forces are approximated using the 2D Doublet-Lattice Method. The Davenport Spectrum is used to model aerodynamic turbulences near the earth surface. The developed dynamic aeroelastic model is employed to investigate the effects of discrete and random gusts on the pointing accuracy of the antenna. It is found that the deviation in the pointing angle is more prominent in the z (azimuth) direction and it displays a quadratic dependency with respect to the mean wind speed. This behavior is attributed to the inertial component of the aeroelastic response solution represented by the gravitational field acting on the center of gravity of the main reflector and the counterweights. The developed efficient aeroelastic model can be integrated into the antenna control system for its response prediction and mitigation.

Effects of different abiotic and biotic factors on spatial primary seed dispersal in the semachorous species Scrophularia canina

AbstractSeed dispersal is one of the most important steps in the plant life cycle. However, there is, generally, a lack of fieldworks focused on wind dispersal and especially on semachorous dispersal (seeds spread when the fruits are shaken by wind and other vectors, such as animals), including boleochorous dispersal. Therefore, we aimed to determine how different types of wind and animals affected seed dispersal under natural conditions in the widespread species Scrophularia canina. We evaluated the effects of wind gusts (simulating them using a leaf blower) and wild animals (using differently sized dogs) on seed dispersal in a population located in south‐western Europe. We found that S. canina is a semachorous species, and its spatial seed dispersal was affected by wind gust speed and direction, plant structure and vector type. The results also revealed the presence of xerochasy, individual anisotropy with strong winds, and primary short‐distance dispersal associated with successional processes independent of the vector. Additionally, there was a masking effect of plant structure on the seed shadow outline. It is essential to conduct fieldworks to reveal what actually happens in nature, taking into account the characteristics determining seed dispersal. In addition, in these works it is important to find out what factors affect seed distributions of anemochorous and semachorous species.

Preliminary study of regulation technology of wind field distribution on QTT site based on test of equivalent wind field

The effect of wind gust on the large reflector antenna is one of the main factors that can affect the antenna performance and therefore, this effect must be minimized to meet the strict performance requirement in the world largest steerable telescope, which is QiTai Telescope (QTT). In this paper, the characteristics of the topography as well as the wind distribution around QTT site have been analyzed and consequently, a technology for improving the wind distribution in an active way has been proposed. Additionally, an equivalent wind distribution test rig for the proposed technology has been built in the lab and the corresponding experiment has been carried out. The experimental data indicated that the proposed technology was a promising tool for regulating the wind distribution for the large reflector antenna and it was found that the proposed technology can significantly reduce the wind speed as well as the wind impact range after the wind regulation has been given in the test. The results in this paper has provided a solid foundation for the regulation of the wind distribution of the QTT site.

Hybrid PD-Fuzzy and PD Controllers for Trajectory Tracking of a Quadrotor Unmanned Aerial Vehicle: Autopilot Designs and Real-Time Flight Tests

This paper presents a hybrid nonlinear control system, comprising of a conventional proportional-differential (PD) controller and a PD-type fuzzy logic autopilot for the trajectory tracking of a quadcopter drone. Given the inherent nature of traditional control, which is model-based, and the essence of fuzzy logic control, which is knowledge-based, the proposed hybrid controllers can provide a more robust solution in the face of uncertainties. Both controllers operate in a parallel incremental form to improve the transient performance and the robustness of the closed-loop control system. Through extensive computer simulations supported by real-time flight tests, this paper highlights the efficacy of the proposed hybrid control system in the presence of some parameter variations, nonlinear aerodynamic models, and some external disturbances (e.g., wind gusts). The Dryden and 1–cos turbulence models are employed to represent the effects of wind gusts under realistic flight environments. The stability analysis of the closed-loop control system is conducted using Lyapunov’s indirect method.

THE TOPPLING OF AN IRRIGATION CENTER PIVOT SUBMITTED TO WIND ACTION EFFECTS

ABSTRACT This research aims to improve the study about the stability of truss structures used in pivot irrigation, widely used due to the growing demand for food production, when submitted to wind effects. Specifically, it aims to verify the maximum wind speed supported by an irrigation center pivot structure when submitted to the load effects caused by wind gusts perpendicular to the equipment. In order to determine these forces and their effects on the irrigation equipment, computational numerical investigations were carried out using finite element bar models validated by measuring the natural frequency of the equipment in the field. A span was designed based on the existing standards in Brazil and the dynamic response of the structure was examined under the effects of wind gusts. Models of the Brazilian standard NBR 6123/88 for structures submitted to wind effects were used in this study. The studied irrigation equipment supports wind gusts of up to 115 km/h applied perpendicularly, with a duration of 3 s, before generating toppling.

Double-arm steel connector of glass façades

This paper presents a numerical analysis of a steel double-arm connector, according to the authors’ solution, designed for fixation of glass façades. The analysis was carried out in order to obtain a distribution of stresses and displacements, on the basis of which global displacements and maximum stresses were determined. An additional element of the solution was the use of the M8 bolt, as a linking element of the steel walls of both arms. The numerical simulation was performed using the ADINA program, which is based on the finite element method (FEM). The dynamic effect of wind gusts on the glass façade was assumed, taking into account both wind pressure and suction. The adoption of a rectangular element of the glass façade causes an unfavorable load distribution at the connection point. The conducted research allowed to determine displacements and stresses in a steel connector made of S355JR steel. The applicability of the proposed solution for glass façades with a height of up to 100 m has been demonstrated.

Effects of lateral wind gusts on vertical axis wind turbines

This paper investigates the effects of lateral wind gusts on the aerodynamic performance of vertical axis wind turbines. A synthetic approach coupling computational fluid dynamics (CFD) simulations and the double multiple streamtube method is utilized to calculate vertical axis wind turbine performance. For simulating the wind gust response, the resolved gust approach (RGA) models the gust transport throughout the wind field. The effects of wind gusts on the effective wind velocity, angle of attack, torque and power performance are evaluated. The presence of gusts slightly changes the effective wind velocity and angle of attack. Lateral gusts increase the angles of attack in the upwind half period causing premature flow separations in the flowfield, while suppress flow separation by decreasing the angles of attack in the downwind period. The mean torque and power of the three-bladed turbines are enhanced by the lateral sharp-edge gust of 2 m/s by 5% in comparison to the steady wind. Reducing the number of blades to one and doubling the gust velocity make the performance further enhances by 14.7% and 34%, respectively. Finally, the effects of several gust shapes are investigated and discussed.

Effect of wind gusts on the dynamics of railway vehicles running on a curved track

Due to global warming, there is an increasing number of wind gusts that affect the stability of railway vehicles. A railway vehicle running on a curved track during a wind gust is subjected to multiple forces simultaneously, which include the centrifugal force and forces exerted by the wind gust and cant, and they significantly affect the vehicle’s dynamic characteristics as well as its safety. The forces increase the vibration of carbodies and the risk of derailment and overturning of cars; the effect is worse on irregular tracks. In order to review the phenomenon in detail, a 1/20 scale model of a railway vehicle was built to measure the aerodynamic coefficients in five directions—side force, lift force, roll moment, pitch moment, and yaw moment—through a wind tunnel test. The data collected were applied as external forces to a full-scale railway vehicle model traveling on a curved track. Using a multibody simulation software program, SIMPACK, a railway vehicle was modeled, which was then used in the simulation of the dynamic characteristics and safety of vehicles while traveling on a curved track during a wind gust. Using the actual measured track data from the curved zone, a comparison was made on the dynamic characteristics of the car traveling, with and without a wind gust, on a curved track with a railway curve radius of 599 m; also, the difference was analyzed with the direction of the wind gust blowing from inside and toward the center of curvature. The results showed that in the presence of a wind gust blowing from outside the curvature with an average speed of 25 m/s it is advisable to stop train services on grounds of safety.

Effects of wind gusts on a vertical axis wind turbine with high solidity

We present a time-dependent, two-dimensional computational fluid dynamics (CFD) model coupled with the dynamics of the rotor for a height-normalized, small-scale high-solidity vertical axis wind turbine (VAWT) that consists of three straight blades, which are cambered to fit the circular path. The model employs the k-ε turbulence model to approximate unsteady Reynolds-averaged Navier-Stokes equations. The CFD model is validated with data from field measurements. The angular velocity, wind torque, power output and the power coefficient of the rotor are obtained for different wind velocities and gusts from the CFD simulations. A simple rotor velocity feedback control is designed to maximize the power output of the VAWT and implemented in simulations for wind transients. Furthermore, local angle of attack and net incident velocity on the blades are calculated from the local velocity field. Oscillatory transient power coefficient has a very large amplitude owing to the oscillations in the wind torque, but the fluctuations in the generator torque are much smaller despite the large solidity of the VAWT. Overall results show that the proposed coupled modeling approach is an effective tool in evaluation of the transient performance of VAWT systems including the inertial effects of the rotor and the feedback control.

Study of Model Predictive Control for Path-Following Autonomous Ground Vehicle Control under Crosswind Effect

We present a comparative study of model predictive control approaches of two-wheel steering, four-wheel steering, and a combination of two-wheel steering with direct yaw moment control manoeuvres for path-following control in autonomous car vehicle dynamics systems. Single-track mode, based on a linearized vehicle and tire model, is used. Based on a given trajectory, we drove the vehicle at low and high forward speeds and on low and high road friction surfaces for a double-lane change scenario in order to follow the desired trajectory as close as possible while rejecting the effects of wind gusts. We compared the controller based on both simple and complex bicycle models without and with the roll vehicle dynamics for different types of model predictive control manoeuvres. The simulation result showed that the model predictive control gave a better performance in terms of robustness for both forward speeds and road surface variation in autonomous path-following control. It also demonstrated that model predictive control is useful to maintain vehicle stability along the desired path and has an ability to eliminate the crosswind effect.

Dynamic investigations of various civil engineering structures due to ambient and mining tremors

The first part of the study deals with evaluation of dynamic characteristics of selected typical industrial facilities, such as the extraction steel tower, reinforced concrete tower skips. These structures are located in the coal mine area. The constructions of the test items are varied and complicated, which causes difficulties in the research in situ. In the investigation we used normal and emergency operation of lifting equipment, the effect of wind gusts and rhythmic man swaying. The second part of the study involves the determination of the dynamic characteristics of tailing dam. In this case mining tremors were used as the sources of vibration excitations. By using natural vibration excitation source it was possible to determine the lowest frequency of free vibration of the tailing dam. The third part of the paper focuses on the results of measurements of mine-induced ground vibrations and vibrations of residential buildings of various types. Typical one-family masonry houses as well as 5 and 12 storey reinforced prefabricated buildings were examined. The studies were conducted to determine the transmission of free-field vibrations to the building foundations. According to the significant differences between the simultaneously measured ground and building foundation vibrations, results of experimental tests obtained by means of response spectra are essential for the proper adoption of kinematic loads for dynamic models of these structures. The results of experimental studies were the basis for the verification of dynamic models of investigated structures.