In this study, a CFD start-up model has been built after conducting the sensitivity studies to evaluate the self-starting behaviour of the H-type vertical axis wind turbines (VAWTs). The self-starting behaviour of a well-investigated VAWT is used for the model validation, and then the details of aerodynamics of the start-up process have been examined. Finally, the effect of the moment of inertia and

The interaction between the turbulent boundary layer and wake behind various types of two-dimensional cylinders is examined based on the velocity measurements by hot-wire anemometry and particle image velocimetry. Three types of cylinders, such as circular, square, and 1:5 rectangular cylinders, of two different diameters of 5 ​mm and 10 ​mm were employed in this study. The streamwise velocity distributions

To investigate the effects of turbulence integral scale, four rectangular models were tested in grid-generated turbulent flows, and the characteristics of fluctuating pressures on windward surfaces were obtained. The results show that all statistical parameters except the mean pressures depend on both the longitudinal integral scale (Lux) and depth (D) of the model. The root-mean-square (rms) values

The effect of lowering the ground clearance, on train aerodynamics is investigated using IDDES. The high speed train geometry with its full underbody complexity is used in the investigation. The clearance is reduced by installing extra panels on the track. The numerical results are verified and validated by a grid independence study and experimental data. This work shows that, when lowered the clearance

The environmental characteristics of difficult mountainous regions has ruled out the easy installation of buffer structures in tunnels. To address this problem, we proposed the installation of cross passages in an entrance section to alleviate the aerodynamic effects of a high-speed train entering the tunnel. In this study, a slide rail high-speed train experimental aerodynamic model was established

Windstorm damage surveys highlight that the discontinuity in load resistance and transfer of connections in timber-framed housing can lead to total failure of the roof structure. Field surveys of timber-framed houses under construction in Australia also indicated that, for a typical roof configuration, at least three of its six or more roof trusses had common construction defects (i.e. missing nails)

An adequate education in a discipline as vast and articulated as wind science and engineering cannot fail to recognize its origins, developments, fundamentals, advancements and prospects. This paper analyses and discusses the actual state of education by identifying its limits, gaps and strengths, as well as the hard core of knowledge that should constitute the common basis for a mature and modern

Galloping instability can potentially threaten the modern launching of steel-concrete composite bridge girders, due to light weight and bluff shape of the steel box, which is normally launched first. A bridge deck with typical open cross section was selected and investigated in smooth flow through wind tunnel techniques. Aeroelastic tests showed that the classical instability arising from the interaction

In this study, the flow field distribution around an isolated stepped flat roof building and the influence of snow cover on flow fields are investigated by wind tunnel experiments based on particle image velocimetry (PIV) technology. Firstly, the stable snow cover, which is obtained based on the previous wind tunnel test of snowdrift on stepped flat roofs, is made by using 3D printing technology. Then

To study the effect of complex terrain on the wind characteristics of the glide paths at Hong Kong International Airport’s North Runway, wind tunnel testing was conducted in Tongji University’s TJ-3 boundary layer wind tunnel, and Cobra probes were used to measure the wind speed and wind direction at the North Runway glide paths. The effects of terrain on the wind characteristics, including turbulence

This study aims to develop a three-dimensional icing simulation code named WISE (Wind turbine Icing Simulation code with performance Evaluation) integrated into OpenFOAM®. The freely available source code can contribute to icing simulations that require parallel computations. The rotational motion is explained by a Moving Reference Frame (MRF) in both aerodynamic and droplet fields. The thin water

The Reynolds independence has been important for scaled experiments of urban aerodynamics in wind environment engineering. It helps to circumvent the difficulty in conserving the Re number for large scaling ratios. However, the criteria for Re-independence and its working mechanism have not been well investigated quantitatively. In this study, a dimensionless numerical analysis is conducted to provide

The majority of existing studies on tropical cyclone (TC) in the wind engineering community concerned merely with wind structures in a considerably shallow portion of TC’s depth, while wind characteristics in TC’s middle and upper portions and the structural features of other weather elements (e.g., temperature, pressure and humidity) have been less investigated. As a result, there is a lack of understanding

This paper presents a new approach for modelling the evolutionary power spectral density (EPSD) of thunderstorm outflows based on a database of 129 real-scale thunderstorm time-histories. Two equivalent methods of decomposition of the wind velocity are investigated, outlining the derivation of the EPSD. The analyses are based on the hypothesis that the residual turbulent fluctuations can be treated

The Precursor Database Method can be utilised to produce turbulent inlet boundary conditions for a LES to determine the wind loads on a high-rise building. The Precursor Database Method is an embedded method within Computational Wind Engineering but is, however, often a minor subtask in a study and the quality assurance is usually not comprehensive. 4 precursor models are assessed and validated with

This paper discusses different strategies for the extraction of the time-varying mean from wind speed time histories. Due to the advantage of allowing analytical evaluations, the attention is focused on kernel regression techniques, considering different weighting functions, namely a constant, a Gaussian and a cardinal sine weighting function. The problem is firstly treated analytically, and the frequency-domain

This paper assesses wind resource characteristics and energy yield for micro wind turbines integrated on noise barriers. An experimental set-up with sonic anemometers placed on top of the barrier in reference positions is realized. The effect on wind speed magnitude, inflow angle and turbulence intensity is analysed. The annual energy yield of a micro wind turbine is estimated and compared using data

Urban winds can cause a risk to pedestrian safety if not properly assessed. High-rise buildings produce a complex flow field at ground level, where regions of accelerated and recirculating flows are present. Gust wind speeds provide an indication of the maximal speed pedestrian might experience due to the unsteady flow. In this study, low- and high-fidelity numerical and experimental techniques to

Tunnel fire often causes serious consequences because of the large length-width ratio of tunnels. Existing research mainly focused on the stationary fire, but motion fire is more complicated and the movement of other trains has great influence on the fired train when there are more than one train running in the tunnel simultaneously. This study investigates the characteristics of motion fire in one-train

This study numerically investigates the effects of Jacobs bogies on the aerodynamic behaviors of a high-speed train using improved delayed detached eddy simulation (IDDES) at Re ​= ​3.3 ​× ​105. The results of the numerical simulations have been validated against the experimental data obtained from a previous reduced-scale moving model test and a wind tunnel test. The slipstream velocity, wake flow

It is known that vortex shedding behind bluff bodies can be suppressed by introducing some three-dimensional geometric disturbance. Therefore, a new passive control device named wavy railings is proposed to mitigate the vortex-induced-vibration (VIV) of a single box section bridge. The wavy railing is composed of vertical posts and wavy crossbars, which can provide three-dimensional perturbation to

Mountain tunnel is inevitably connected to those canyon areas that could result in a very special situation for the related designs. When the airflow goes through the canyon from an open terrain, it is accelerated to a strong canyon wind under the Venturi effect. However, the flow characteristics in tunnels affected by the canyon wind are still not known. Therefore, the flow characteristics in the

This paper presents a frequency domain approach to determine the expected peak spatial (x, y, torsion) and resultant accelerations of tall buildings tested in the wind tunnel. Auto-spectra and cross-spectra are computed from the generalized force time series determined from measured wind tunnel data. Spectral analysis is used to determine the auto- and cross-spectra of the modal responses from which

It is important to evaluate environmental impact of exhaust gas with high temperature and high-concentration hazardous pollutants from emergency generators in the urban environment. In this study, we conducted wind tunnel experiment on high-buoyancy gas dispersion around an isolated cubic building. Experiments were conducted under three exhaust speed ratios to study their influence on pollutant dilution

The momentum recovery downstream of a Vertical Axis Wind Turbine (VAWT) is analyzed as a function of its dynamic solidity, modified changing both the number of blades and the rotational speed of the turbine. Computations were carried out using Large-Eddy Simulations (LES), coupled with an Immersed-Boundary (IB) methodology. The streamwise increase of the momentum deficit in the near wake was found

Tornadoes are violently rotating columns of air that may be produced by convective clouds and storms, and can produce substantial property damage, injuries, and deaths. To mitigate these losses and encourage accurate modeling and research in the field of civil engineering, with the goal of improving civil structure design, a comprehensive review of field measurements, lab simulations, and computational

It is essential in a bridge design to study the wind parameters at the bridge site, particularly in a complex mountain area where the wind characteristics vary from location to location. The aim of this paper is to study the wind characteristics in a Y-shaped valley in mountainous terrain, the site of a proposed long-span bridge. Data recorded continuously for almost two years by a Doppler Sodar observation

To overcome the limitations of the existing experimental methods (i.e., wind tunnel test and in-situ measurement) for wind engineering research of bridges, a new experimental method is proposed, i.e., studying the wind-resistant performance of bridges based on large-scale deck sectional models and full bridge aeroelastic models in natural wind. The representative wind field data are offered to briefly

Reliability based design optimization (RBDO) for deck shape and thicknesses of the steel plates that form a box girder of long-span suspension bridges is performed considering probabilistic flutter constraint. The entire process was carried out fully computationally including the definition of flutter derivatives. Surrogate models were constructed to estimate the aerodynamic response of the bridge

The impact of flow-normal ribs and small-scale surface roughness on the drag and vortex shedding of a circular cylinder was investigated. Three rib heights, four relative rib spacings and three different forms of micro-roughness were combined to produce 28 unique surface coatings for the cylinder. The drag was measured in a wind tunnel for Reynolds numbers in the range 20,000

Strong winds could cause train derailment and truck rollover which may result in service interruption, serious injury, and even loss of life. The wind-induced accident is highly related to the maximum value of short-term wind speed, thus highlighting the importance of regulating the vehicle velocity based on wind gusts. Accurate prediction of wind gusts is essential to control the vehicle velocity

This paper takes CAARC standard tall building as example to investigate the effects of corner chamfers on the aerodynamic performance of tall buildings. Five rigid tall building models including CAARC standard tall building as benchmark model and four corner chamfered models with different modification rates from 5% to 20% are tested for pressure measurements in a boundary layer wind tunnel. Based

The paper presents results of an extended study of the model developed earlier by the authors for across-wind response of tall circular chimneys to vortex shedding. A non-dimensional parameter,“fact” is used to suitably decrease the spectral bandwidth of the generalized across-wind load spectrum, implicitly accounting for an increase in load correlation. This paper discusses similarity between the

In order to study the effect of the strip spacing on the aerodynamic noise characteristics of the pantograph of high-speed train, the numerical simulation of the aerodynamic flow behavior for the high-speed pantograph is conducted using the detached eddy simulation (DES) and its aerodynamic noise is studied using the FW-H model. The numerical method is verified by flows around a cylinder with a finite

The present work mainly focuses on the evolution of the airflow passing embankments of different heights, with and without trains. Using the delayed detached-eddy simulation (DDES) method, the effects on the velocity and acceleration of the airflow caused by the embankments’ upstream slope were studied using a set of embankments with different heights. The aerodynamic loads experienced by each car

The aerodynamic loads on the overhead bridge bottom surface induced by train passage are reported in this paper. Both moving model test and numerical simulation approaches at the 1:20 scale are used. The numerical work is validated through both mesh independence tests and comparison with experimental data. Typical pressure variation curves are plotted and compared with previous studies. The peak pressure

To investigate the effect of suction control on the aerodynamic characteristics of an elliptical cylinder immersed in uniform flow, wind tunnel tests of four elliptical cylinder models E1~E4 with different locations of suction holes were carried out under different suction flux coefficient CQ. The Re number based on the equivalent diameter of each model and the oncoming wind speed is about 6.90 ​× ​104

This paper considers a process through which the wind costs the agricultural industry hundreds of millions of pounds per year - crop lodging. Lodging is the displacement of crops by wind (and rain) that can result in either stem breakage or uprooting. In particular this paper builds upon recent work to develop a generalised model of the lodging process and presents the results of several experimental

A series of wind tunnel tests were performed to investigate the effect of turbulent inflows on the aerodynamic characteristics of variously modified leading-edge protuberanced (LEP) wing configurations at various turbulence intensities. A self-developed passive grid made of parallel arrays of round bars was placed at different locations of the wind tunnel to generate desired turbulence intensity. The

For a 5:1 rectangular cylinder, the large eddy simulations (LES) are carried out to systematically evaluate the influences of the cylinder spanwise length (L) and spanwise mesh size (δz) on the aerodynamic forces, spanwise-averaged quantities, and flow features. The L varies from 10D to 2.5D, and δz varies from 0.1D to 0.0125D, where D is the cylinder depth. The new simulation cases of L ​= ​2.5D and

The present investigation is concerned with the phenomenon of aerodynamic interference across three cases: between two circular cylinders; a pair of 1:50 tapered cylinders; and a pair of 1:40 tapered cylinders—all in staggered arrangement. Experiments were conducted in the 1.6 ​m × 1.6 ​m wind tunnel at IIT Delhi. Our focus is on the enhanced across-wind response of the downstream cylinder near the

The non-linear aerodynamic effects on a bridge deck section are both experimentally and numerically investigated using a new time-domain numerical model based on the combination of a non-linear corrected quasi-steady theory and a rheological approach. The model is developed to reproduce the response of a bridge to turbulent wind taking into account the non-linearities of the aerodynamic forces induced

We analyzed the datasets of the flow fields at a pedestrian level around a 1:1:2 isolated block model obtained by a large eddy simulation. The purpose was to understand the effect of the block on the probability density distributions of each velocity component and wind speed, and to propose a reasonable model to predict the percentile values of wind speed (exceeding wind speeds) for the pedestrian

The slope of a hill could affect the flow patterns significantly. In the present study, three smooth three dimensional (3D) hills (H2, H4, and H8) and three smooth two dimensional (2D) ridges (R2, R4, and R8), with the hill heights increased by factors of 2.0 while the hill radii are kept constant to achieve different slopes, are examined systematically using large eddy simulations (LES). The reattachment

Three typhoons approached the southeast coast of China during August 2012. The structural health monitoring (SHM) system recorded in-situ environmental factors (including wind speed and temperature) and structural responses (including displacements and acceleration) during the whole period. Based on the recorded SHM data, the variation features of the environmental factors and structural responses

The experimental study is conducted to investigate the heat exhaust efficiency with different shaft heights and heat release rates (HRRs) in a 1:10 tunnel model. The degree of plug-holing below the exhaust vent is considered. The smoke characteristics in upstream and shaft, such as flow velocity and smoke temperature rise, are discussed in this paper. The results indicate that the smoke movement in

The supergradient winds that may have severe implications on the wind design of high-rise buildings have been commonly observed in the hurricane boundary layer. However, the widely-used log-law or power-law wind profile excludes the supergradient-wind region in which the tangential winds are larger than the gradient winds. Although high-fidelity, nonlinear hurricane wind models may well capture the

Naturally ventilated livestock buildings (NVLB) represent one of the most significant sources of ammonia emissions. However, even the dispersion of passive gas in an NVLB is still not well understood. In this paper, we present a detailed investigation of passive pollutant dispersion in a model of a cattle barn using the wind tunnel experiment method. We simulated the pollution of the barn by a ground-level

Ducted Wind Turbines (DWTs) can be used for energy harvesting in urban areas where non-uniform inflows might be the cause of aerodynamic and acoustic performance degradation. For this reason, an aerodynamic and aeroacoustic analysis of DWTs in yawed inflow condition is performed for two duct geometries: a baseline commercial DWT model, DonQi®, and one with a duct having a higher cross-section camber

Flutter analysis that governs the bridge aerodynamic instability is crucial during the wind-resistance design period of long-span bridges. However, randomness existing in the wind load and structure can bring about obstacles in the determination of the flutter onset and thus can lead the bridge to precarious situations. Probabilistic analysis considering the uncertainties from different sources is

Alleviation of the pressure transients caused by high-speed trains intersecting in a tunnel with partially reduced cross-section is investigated by numerical simulation. The RNG k-ε turbulence model and hybrid grid are adopted for the numerical simulation, which is validated by the moving model test. Two factors, the length of reduced section (L) and the train marshalling number, are considered to

Producing metallic wind-tunnel models with integrated pressure taps (i.e. taps formed during the manufacture process) via additive manufacturing (AM) techniques could present several advantages over conventionally manufacturing (CM) pressure-tapped models. However, there are limited reports of AM wind-tunnel models in general. This study describes, in brief, the design and manufacture of a metallic

The variation laws of flow field structure leeward a corrugated wind barrier with different bending angles and their sheltering performance on a train above a railway bridge were studied in the present work. Wind tunnel tests with and without a vehicle body were carried out, and the corresponding numerical simulations were conducted. A good agreement between the simulation and the corrected experimental

Understanding the persistence in time series is of crucial importance relating to the reliable forecast of wind speed. It has been widely acknowledged that fractal analysis is a useful tool to evaluate the persistence in wind speed time series using the fractal dimension (D) as a quantitative indicator. This paper aims to unveil the persistent characteristics of wind speed time series recorded under

Reducing train pantograph noise is particularly important. In this paper, the flow behaviour and noise contribution of simplified geometries representing high-speed train pantographs and the roof cavity at 1/10th scale are investigated. The Improved Delayed detached-Eddy Simulation (IDDES) turbulent model is used for the flow field simulation and the Ffowcs Williams & Hawkings aeroacoustic analogy

A series of experiments were carried out in a model-scale tunnel to investigate the confinement velocity in the tunnel fire with longitudinal ventilation. The significance of longitudinal ventilation to the smoke control in tunnel fire was comprehensively elaborated by both the variation of smoke back-layering length in the upstream and the characteristics of smoke layer in the downstream which was

Interference effects of tall buildings have attracted numerous studies due to the boom of clusters of buildings in megacities. To fully understand the interference effects, it often requires a substantial amount of wind tunnel tests. Limited wind tunnel tests that only cover part of interference scenarios are unable to fully reveal the interference effects. This study used machine learning techniques

Detailed studies on wind turbines have been attracting increasing attention in recent years in order to save fossil resources and protect the environment. Vertical axis wind turbines (VAWTs) are not as popular as horizontal axis wind turbines (HAWTs) because of their relatively low efficiency. Based on CFD approaches, this paper studies the influence of the aerofoil’s maximum camber as well as its