Wind Action Research Articles

Effect of ambient wind on horizontal flame spread over discrete multi-column fuel arrays

The flame spread behaviors of discrete charring fuels are significantly influenced by ambient wind. This paper studied the horizontal flame spread characteristics of discrete birch rod arrays under ambient wind experimentally and theoretically. Here, seven kinds of array spacings (denoted by S, 7–19 mm) and four kinds of wind speeds (denoted by U, 0.5–2.0 m/s) were designed to develop 28 experiments. The experimental results show that the flame inclination angle decreases as wind speed increases. The non-dimensional flame length and the non-dimensional heat release rate are also found to be correlated, and two ignition modes under the action of ambient wind were differentiated. The flame spread rate and wind speed have a linear relationship based on experimental data. The ratio of wind speed to fuel loading is introduced to further examine the variation of flame spread rate. In this article, a heat transfer model is established by simplifying discrete flame spread process and incorporating both radiative and convective heat transfer. A prediction model for flame spread rate is presented, which aligns well with the experimental results. Finally, the mass loss rate under the ambient wind is discussed.

Turbulent Exchange in Unsteady Air-Sea Interaction at Small and Submesoscales

An adequate description of the interaction between the atmosphere and ocean remains one of the most important problems of modern oceanology and climatology. An extremely wide variety of physical processes occurring in the coupled layers, a large range of scales, a moving boundary, all this factors significantly complicates the creation of models that would allow calculating the physical characteristics in both media with the necessary accuracy. In this paper the temporal variability of dynamic parameters in the driving layer of the atmosphere and in the near-surface layer of the sea on small and sub-mesoscales from one to several tens of hours is considered. The collected experimental data show a very high correlation between the dynamic wind speed and turbulence intensity in the upper sea layer on all scales recorded. An important distinguishing feature of all measured physical quantities in both media is the presence of quasi-periodic oscillations with different periods. For a more accurate description of momentum and energy fluxes from the atmosphere a non-stationary model of turbulent exchange in the near-surface layer of the sea is proposed. The model takes into account quasi-periodicity in the intensity of dynamic interaction between the atmosphere and the sea at these scales. In the model we use the equations of momentum and turbulent energy balance, the system of equations is solved numerically, the calculation results are compared with other models and with experimental data. It is shown that taking into account the non-stationarity of the wind strain improves the correspondence between the calculations and the experimental data. It is noted that in the nonstationary case, the energy and momentum flux from the atmosphere and the turbulence intensity increases compared to the action of a constant average wind of the same duration. Therefore, the strong averaging often used in global models may markedly underestimate the intensity of the dynamic interaction between the atmosphere and ocean.

Evolution characteristics and mechanism of meso-γ-scale vortex in an atypical bow echo in the North China Plain

On June 25, 2020, an atypical bow echo (ATBE) accompanied by a meso-γ-scale vortex (MV) incurred the strongest gust (41.4 m s−1) recorded since 1957 in the North China Plain. In this article, we investigate the evolution characteristics of MV and its mechanism for the extreme wind by using the observation data of Doppler weather radar and automatic weather stations as well as the four-dimensional Variational Doppler Radar Analysis System (VDRAS). The results show that the MV in this process was initially born at a height of 0.9–2.4 km, and the contracting and stretching vertical vortex rapidly descended to surface from the 2.0 km height with the rotation speed increasing rapidly. Six minutes later, the extreme wind occurred. The generation mechanism of the MV is that, under the strong vertical wind shear and downdraft in the lower troposphere, the vertical vortex tube of MV was transformed from the horizontal vortex tube generated in the zone of perturbation temperature gradient. The influence mechanism of MV on the extreme wind is that, as the MV continued to intensify and extend downward, a negative perturbation low-pressure center formed in the lower troposphere near the MV. Meanwhile, the descending rear-inflow jet (RIJ) was blocked by the prefrontal upward motion and a positive perturbation high-pressure center formed at around 1 km height. The violent positive-negative couplets of perturbation pressure gradient produced a downward nonhydrostatic perturbation pressure gradient force (NPPGF) that further intensified the vertical downward velocity. In addition to the strong downdraft velocity, the Coriolis force also enhanced the formation of the extreme wind through the action of ageostrophic winds. Besides, this paper also compares the mechanism of this process with that of a typical bow echo MV and the extreme wind it affected.

Safety of the express freight train running over a long-span bridge

PurposeExpress freight transportation is in rapid development currently. Owing to the higher speed of express freight train, the deformation of the bridge deck worsens the railway line condition under the action of wind and train moving load when the train runs over a long-span bridge. Besides, the blunt car body of vehicle has poor aerodynamic characteristics, bringing a greater challenge on the running stability in the crosswind.Design/methodology/approachIn this study, the aerodynamic force coefficients of express freight vehicles on the bridge are measured by scale model wind tunnel test. The dynamic model of the train-long-span steel truss bridge coupling system is established, and the dynamic response as well as the running safety of vehicle are evaluated.FindingsThe results show that wind speed has a significant influence on running safety, which is mainly reflected in the over-limitation of wheel unloading rate. The wind speed limit decreases with train speed, and it reduces to 18.83 m/s when the train speed is 160 km/h.Originality/valueThis study deepens the theoretical understanding of the interaction between vehicles and bridges and proposes new methods for analyzing similar engineering problems. It also provides a new theoretical basis for the safety assessment of express freight trains.

A complete environmental wind tunnel for studying the evolution of snow accumulations under the effects of wind, rain, and heat

Given the escalating frequency of extreme cold weather worldwide, snow-induced building failures have increased substantially, especially in large-span space structures. The reason for engineering accidents lies in a lack of understanding of the intricate process of the mechanism of full-period evolution of snow “accumulation-melt-crystallization- accumulation” under the coupling actions of wind, rain, and heat. It is significant to develop a comprehensive and accurate environmental wind tunnel for conducting snow-relevant experiments under the multi-factors, which are barely studied. Hence, this paper proposes and establishes an experimental system called “Simulator of Natural Action of Wind-Rain-Heat-Snow for Space Structures (SNOW).” The system consists of an atmospheric boundary layer cryogenic wind tunnel subsystem, snowfall simulation subsystem, rain simulation subsystem, solar and building heating simulation subsystem, and high-precision multi-task monitoring and control subsystem. The facility can provide a 0–20 m/s stable wind field, −15 °C–0 °C low-temperature conditions, and a 2 m × 2 m experimental section. The calibrations of each subsystem were conducted in SNOW to ensure each component can successfully provide basic conditions for snow-relevant experiments. The SNOW can accurately simulate the entire process of natural snowfall and snow evolution under the coupling effects of wind, rain, and heat.

Lyapunov stability of suspension bridges in turbulent flow

In the era of sleek, super slender suspension bridges, facing the issue of stability against dynamic wind actions represents an increasingly complex challenge. Despite the significant progress over the last decades, the impact of atmospheric turbulence on bridge stability remains partially not understood, evoking the need for innovative research approaches. This study aims to address a gap in current research by investigating the random flutter stability associated with variations in the angle of attack due to turbulence, which has not formally been addressed yet. The present investigation employs the 2D rational function approximation model to express self-excited forces in a turbulent flow. The application of this type of models to bridge dynamics yields a viscoelastic coupled dynamic system characterized by memory effects and driven by broad-band long-time-scale noise, described here by a linear homogeneous time-variant differential equation, which shows apparent nonlinear features, and which has rarely been matter of research. Utilizing a Monte Carlo methodology, this work innovates in applying the largest Lyapunov exponent (LE) and the moment Lyapunov exponents (MLE) to study bridge random flutter stability. The calculation of LE and MLE under diverse turbulent wind conditions uncovers lower flutter stability than without turbulence effects. In most cases, sample and low-order p-th moment stability thresholds closely align with the bridge dynamic response pattern; therefore, the flutter critical wind speed is unequivocal. However, under certain turbulence scenarios, it is necessary to resort to MLE for a complete description of stability, evoking some additional consideration of which statistical moments should be considered for the engineering assessment of the flutter limit. Finally, this work provides a qualitative insight into the instability mechanisms by approximating the random parametric excitation with a sinusoidal gust and evaluating the time-periodic system stability via Floquet theory.

A methodology to evaluate seawater corrosion on quasi-static tensile properties of a structural steel

With the wind turbine industry growing and increasingly turning its focus to the offshore sector, it is important to grasp the challenges that come with it: the logistic challenges related to transport and maintenance, the exposure to wave and wind action and also the vulnerability to corrosion. The marine environment is a complex and aggressively corrosive environment. The S690 steel, as a structural steel of high mechanical strength, offers weight reduction advantages that are of interest to the sector. However, its behaviour in a corrosive medium is still not well known. As such, this work is part of an effort to characterize S690 steel under marine environment conditions. A methodology for inducing accelerated pre-corrosion on quasi-static tensile specimens of S690 steel, while simulating the environment, has been developed and applied. The effect of this pre-corrosion on the tensile mechanical properties is evaluated through testing in accordance with the ASTM E8 standard. It was found that the induced surface pre-corrosion, equivalent to six months of exposure, did not have a significant effect on the investigated mechanical behaviour.

Research on the Blades and Performance of Semi-Submersible Wind Turbines with Different Capacities

With the gradual increase in the maturity of wind energy technology, floating offshore wind turbines have progressively moved from small-capacity demonstrations to large-capacity commercial applications. As a direct component of wind turbines used to capture wind energy, an increase in the blade length directly leads to an increase in blade flexibility and a decrease in aerodynamic performance. Furthermore, if the floater has an additional six degrees of freedom, the movement and load of the blade under the combined action of wind and waves are more complicated. In this work, two types of semi-submersible wind turbines with different capacities are used as the research objects, and the load and motion characteristics of the blades of these floating offshore wind turbines are studied. Through the analysis of the simulation data, the following conclusions are drawn: with the increase in the capacity of the wind turbine, the flexible deformation of the blade increases, the movement range of the blade tip becomes larger, the blade root load increases, and the power fluctuation is more obvious. Compared with the bottom-fixed wind turbine, the flexible blade deformation of the floating offshore wind turbine is smaller; however, the blade root load is more dispersed, and the power output is more unstable and lower.

Analysis of structural dynamic response of vertical sound barriers under natural wind and vehicle induced pulsating wind effects

Abstract Aiming at the influence of natural wind and vehicle-induced pulsating wind on vertical sound barriers, a finite element plug-in panel sound barrier is established based on the finite element method for dynamic response analysis. This paper establishes a sound barrier finite element analysis model based on finite element analysis software. It takes the 8-span vertical sound barrier as the basic working condition to analyze the dynamic response analysis of the sound barrier structure under the action of natural wind of different grades, i.e., the influence of pressure and displacement; the dynamic response of the sound barrier structure with a natural wind speed of 7 grades or more. In addition, it analyzes the dynamic properties of the sound barrier structure caused by train-induced pulsating wind pressure at speeds of more than 200 km/h, i.e., the influence of pressure and displacement, and investigates the dynamic characteristics of different vehicles with different wind speeds, pressure, and displacement. Furthermore, the response of the vertical sound barrier at different vehicle speeds is also explored, and the results are compared to examine its dynamic response. The research findings show that the sound barrier structure does not resonate during the self-resonance analysis, but the vibration of adjacent sound barrier panels affects each other. As natural wind speeds increase, the displacement of the steel column endpoints of the vertical sound barrier gradually increases; along the length of the sound barrier, the change of the peak pressure at the top of the steel columns and the top of the unit plate shows a symmetrical trend, and the displacements of the steel columns and the top of the unit plate show a trend of gradual increase in the travelling direction, and they both increase at the end of the column. The displacement of the top of the steel column and the top of the unit plate both show a trend of gradual increase along the direction of the vehicle, and both reach the maximum value at the end of the steel column and the unit plate. With the increase in vehicle speed, the overall peak displacement value also increases synchronously.

Analysis of tower structure for fatigue taking into account wind vortex shedding

Vortex shedding is manifested in all tower structures with a solid or lattice cross-section with relatively equal width and depth of the cross-section. The phenomenon is associated with the alternate breakdown of vortices from the edges of the structure, which cause it to oscillate under the influence of inertial masses in a plane perpendicular to the wind. The main condition for the manifestation of vortex shedding is the action of wind with a speed exceeding a certain critical one. As shown by calculations of a real tower structure, oscillations according to the first natural frequency and shape occur already under the influence of a moderate wind. This requires attention, assessment of the number of oscillation cycles and the implementation of criteria for taking into account the combined effect of frontal wind and vortex shedding on the structure and calculation of the structure for endurance. The paradox is that this phenomenon is not widely known in engineering practice, and instructions on the mandatory calculation of structures for vortex excitation appeared only with the implementation of amendment 2 to DBN B.1.2-2:2006 "Loads and influences. Design norms" in 2020. In this analyzed state of research on this issue, an available method for calculating vortex excitation, introduced in EN 1991-1-4:2005, is presented. The calculation and analysis of the McDonald's advertising totem with a height of 25.575 m, implemented in Kyiv in 2016, was performed. Calculations showed that this structure is characterized by oscillations due to vortex shedding. From the available sources of meteorological data, an approximate number of oscillation cycles was determined, criteria for calculating the structure's durability were determined, and generalizations were made that can be applied to all structures. In particular, it is pointed out the need to limit stresses beyond the endurance limit in two ranges - parametric resonance from the frontal wind, and sign-changing cyclic oscillations from vortex excitation. An analysis of the effective cross-sections and effective structural forms of building details when working under the action of a frontal wind with vortex shedding was carried out.

Revealing the influence of wind vortex shedding on the stressed-strained state of steel tower structures with solid cross-section

This work investigated the effect of vortex shedding during the action of wind on tower structures with a solid cross-section. Failure to take into account this influence, together with the manifestation of the phenomena of physical wear of structures during long-term operation, can lead to building accidents. The object of the research are tower structures with a solid cross-section, which are widely used in modern infrastructure ‒ advertising pylons with a transparent advertising structure with a height of about 12, 22, 25 m, and a flagpole with a height of 48 m. The most frequent manifestations of oscillations according to the first natural frequency and shape have been considered, which occur even with moderate winds and when a large number of oscillation cycles occur. In this work, the number of oscillating cycles per year was determined and estimated based on the archive of meteorological observations. It was found that the number of oscillating cycles due to the action of wind excitation for the example of the structures under study is from 2.6 to 14.4 million per year, which requires the mandatory limitation of stresses in the parts of structures during the design to enable their durability. The magnitude of forces from vortex shedding for the studied structures ranges from 2.9 to 43.5 % of the forces caused by the influence of the frontal wind, depending on the height of the structure. Thus, it was found that the influence of vortex shedding is very insignificant for structures up to 12–15 m high and increases for structures 20 m and higher. Rational forms of the cross-sections of structures were established to reduce the influence of vortex shedding ‒ these are cross-sections of a circular and a cross-section close to it. In a general formulation, these are sections for which peak stresses relative to forces in one plane fall into the neutral zone for stresses from forces in another plane. Recommendations have been also given on the simultaneous consideration of forces from the action of frontal wind on the structure and vortex shedding since both manifestations of wind action on tower structures cannot be separated

Stress Distribution along the Structural Sealant Joint Length of a Cylindrically Curved Glazing Panel

It has been identified that current standardised method for structural sealant joint dimensioning is applicable to flat rectangular panels only and no provisions are made for panels with curved surfaces. The purpose of this study is to investigate the stress distribution along the sealant joint of a cylindrically curved glass panel subjected to wind pressure and to establish if the panel curvature influences the stress distribution along the joint length. Using numerical method, several curved units were analysed and the results have shown that the out of plane wind action generate compression and shear forces within the joint, both occurring at the same time. This means that in the case of a structurally bonded curved panel, additionally to the shear caused by differential thermal expansion of elements or glass self-wight which is covered by ETAG 002 and EN 13022 the designer must also consider the shear stress induced due to the panel curvature. The magnitude and location of this additional shear stress and also of the tension/compression stress can be identified using Finite Element Analysis.

Effects of steady-state fluid-structure interactions on air-supported membrane structures subjected to wind actions

With the perspective of static aeroelasticity, steady-state influences of fluid-structure interaction (FSI) on wind loads and responses of rectangular-planed air-supported membrane structure (ASMS) are investigated in this study. Steady-state FSI simulations are performed by coupling Reynolds-averaged computational fluid dynamics solving wind loads and static finite element analysis solving structural deformations. The feasibility of these simulations is validated with wind tunnel tests concerning time-averaged results. In contrast to analysis without static aeroelasticity, significant variations in wind pressure distributions and amplifications on structural wind responses due to steady-state FSI effects are observed. Subsequently, influencing factors and mechanisms of steady-state FSI effects are analyzed. These time-averaged effects are more significant with the increasing magnitude of structural wind actions, lower internal pressures and less membrane tensile stiffness. Though unlikely to induce irreversible effects as shell structures, the buckling of ASMS can make steady-state FSI more pronounced because of the coupling between stronger flow separation and larger membrane deformations. Accompanied with steady-state FSI, such buckling effect usually contributes to varying locations of the structural maximum responses and noticeable increases in response amplification factors, which deserves attentions in practice. Practically, it is realizable to evaluate these steady-state FSI effects above with simulations because of the much lower computational cost and reliable accuracy.

Effect of wind conditions on the performance of an Oscillating Water Column energy converter

Local atmospheric conditions surrounding an off-shore Oscillating Water Column device — OWC hereinafter —, in particular wind action, may affect OWC performance and efficiency, specially over long harvesting intervals, i.e. yearly energy production. This work proposes an experimental study of a simple off-shore OWC where different ambient conditions are compared. More specifically, it proposes a set of experimental tests in laboratory wave flume, under both calm and external wind conditions, which represent a more realistic situation in full-scale prototypes. The results show that the external wind modifies the ambient conditions by changing the temperature, humidity and pressure values of the air surrounding the OWC device, affecting the density and the thermodynamic balance. This affects negatively the OWC performance, reducing the maximum pneumatic power by up to 15%, which can be extrapolated to a reduction of 3% in the total amount of annual energy produced.

Sediment transportation by strong winds over Gobi surfaces: Field observations along the Lanzhou–Xinjiang high‐speed railway

AbstractUnder strong wind action over vast Gobi surfaces, eolian transportation can cause significant environmental problems and infrastructural damage. However, scientific understanding of the underlying mechanisms and dynamics of this process in the Gobi region remains limited. To address this gap, our study focused on investigating eolian transportation over the Gobi surface along the Lanzhou–Xinjiang high‐speed railway (LXHSR) in Northwest China, where strong winds are prevalent. The results indicate that sand transportation heights can reach 9 m in this region, with the saltation layer approximately 3–6 times higher than that of other gravel deserts. The sediment flux density over the Gobi surface exhibited an exponential decrease with increasing elevation; however, the grain‐size vertical profile in wind‐blown sand displayed an increase up to a critical altitude, followed by a decrease with height. The annual eolian transported quantity recorded in this region exceeds that of most deserts worldwide. Notably, fine sand and total suspended particulates (TSP) contributed to approximately 90% of the sediment deposited on railway tracks and drawn in by passing trains. To control transportation of these fine particles, we propose increasing the height of sand‐blocking fences within the current railway wind‐blown sand protection system from 2 to 3 m. Simultaneously, anthropogenic damage to the Gobi surface should be minimized to reduce excessive dust release. This study provides insight into the wind‐blown sand movement mechanism over the Gobi surface under strong winds, and the eolian physics parameters revealed may serve as a theoretical foundation for preventing and managing eolian catastrophes along the Lanzhou–Xinjiang high‐speed railway.

Precipitation Simulation and Dynamic Response of a Transmission Line Subject to Wind-Driven Rain during Super Typhoon Lekima

Typhoons bring great damages to transmission line systems located in coastal areas. Strong wind and extreme precipitation are the main sources of damaging effects. Transmission lines suffered from wind-driven rain exhibit more susceptibility to damage due to the coupled effect of wind and rainwater. This paper presents an integrated numerical simulation framework based on mesoscale WRF model, multiphase CFD model and FEM model to analyze the motions of a transmission line subjected to coupled wind and rain loads during typhoon events. A full-scale transmission line in Zhoushan Island is employed to demonstrate the effectiveness of the proposed framework by simulating typhoon evolution in terms of wind fields and rainfall, solving the coupled wind and rain fields around the conductor and predicting the dynamic responses of the transmission line during Super Typhoon Lekima in 2019. The results show that the horizontal displacements of the transmission line under the joint actions of wind and rain increase approximately 17–18% compared to those of wind loads only. It is important to consider the coupled effects of wind-driven rain on conductors in the design of transmission lines under typhoon conditions.

Mechanical behavior of ship to shore container crane subjected to different stochastic wind actions.

Mechanical behavior of ship to shore container crane subjected to different stochastic wind actions.

Ammonia – an assessment of potential environmental impacts including prevention and mitigation measures

Ammonia (chemical formula NH3) is one of the most widely produced chemicals for industrial and agricultural uses. Ammonia has gained attention as a potential hydrogen and energy carrier, and low carbon substitute fuel for rail and maritime transport. The potential of ammonia for new use cases may lead to an increased footprint of potential environmental impacts. The physical and chemical properties of ammonia offer significant benefits for transportation and storage, but challenges remain due to its highly toxic nature and uses outside of dedicated industrial precincts. Ammonia is typically liquefied to increase density for ready storage and transportation. Unplanned releases of liquid ammonia will result in immediate environmental impacts. Unplanned releases may adversely affect receptor species in aquatic and terrestrial environments, human health, as well as the reputation of the responsible organisation. Dispersion of ammonia into the environment depends on factors that include mixture density, temperature, humidity, wind and wave action, and release mode and direction. Understanding the fate of ammonia is fundamental to adoption of effective mitigation measures. Consequently, it is necessary to understand the behaviour of ammonia in the environment, how unplanned releases can be minimised, and how they can be combatted, in order to appraise its suitability as a low carbon liquid transport fuel. This paper assesses the risks posed by ammonia spills, its fate in aquatic environments, and the applicability of available spill models. It also addresses management measures for the prevention and mitigation of spills noting the highly soluble and toxic nature of the chemical.

Performance of multiple tuned inerter dampers optimized by a cultural algorithm to control response in buildings subjected to ground acceleration

The reduction of the response parameters of civil structures subjected to the action of wind or ground accelerations is one of the main objectives of the implementation of a structural control system. Many investigations have been developed to make progress and contributions to the design and implementation of effective, reliable, and economical control devices. Therefore, this paper explores the performance of different configurations of multiple Tuned Inerter Dampers (TIDs) in buildings excited by earthquakes. TIDs are passive control devices that enhance a viscous damper by incorporating a novel mechanism known as an inerter. The inerter amplifies an apparent mass that is used to dissipate energy in the controlled system. Four different control alternatives with one, two, three, and four TIDs in the structure are studied. The determination of the optimal design parameters of the different control alternatives was carried out using a novel and very promising optimization process based on a Cultural Algorithm (CA), which has great potential due to being a fast, precise, and reliable method, which is not traditionally associated with the optimization of seismic protection devices. The CA was tuned through a parametric study and compared in terms of performance with an optimization process based on an exhaustive search. A case study of a 12-story building subjected to the action of different ground motions was developed in which the proposed optimal control alternatives were tested. The results showed a significant effectiveness of the control alternatives using multiple TIDs, achieving reductions in peak displacements, RMS values of the maximum displacements and the maximum interstory drifts of up to 54 %.

Performance Optimization Design Study of Box-Type Substations Subjected to the Combined Effects of Wind, Snow, and Seismic Loads

As a pivotal node in both urban and rural power grids, the box-type substation not only serves the functions of power conversion and distribution but also need to provide structural support and environmental adaptability. However, deficiencies in strength, stiffness, or vibration characteristics may lead to vibration and noise issues, and extreme environmental changes can pose risks of structural damage. This study aims to verify and optimize the seismic resistance and environmental adaptability of box-type substations through finite element simulation methods. Using SOLIDWORKS, a three-dimensional model of the box-type substation was constructed, and static and dynamic analyses were conducted using Ansys Workbench to comprehensively evaluate the dynamic response of the box-type substation under wind, snow loads, and seismic action. Through iterative simulations and a comparison of multiple design solutions, the structural optimization of the substation was achieved. The optimized structure balances strength and stiffness, significantly reducing the weight of the substation body, with the wall thickness reduced by 60%. Additionally, the phenomenon of stress concentration on the side walls was eliminated, ensuring that the equivalent stress is below the material yield strength. This research provides methods and empirical results for enhancing the performance and reliability of box-type substations under seismic conditions, confirming the feasibility of a lightweight design, while ensuring structural safety.