Wind Flow Characteristics Research Articles

Wind flow characteristics through shrouded wind turbine using ANSYS

Wind energy is a mature and quick-growing source of energy in many nations. New wind energy technologies must be introduced to increase effectiveness and reduce the cost of wind turbine installation. Wind energy conversion experts believe that shrouded wind turbines are a promising technology that could raise output and efficiency levels. A low-pressure zone is created behind the turbine because of the shroud’s unique structure. As a result, the turbine draws in greater mass flow to produce more power. With the aid of this innovative technology, wind turbines could be used in populated areas where lower wind speeds could be captured. In this study, a comparative analysis has been applied to different designs of shrouded wind turbines to analyze the wind speed, pressure, output power and power coefficient. ANSYS software has been conducted in this paper where the results obtained that the output power could be increased up to 3-4 times compared to the bare wind turbine, also a high-power coefficient could be reached up to 83.1%.

Effects of sound on bluff body aerodynamic characteristics in separated and reattaching flows

The coupling effects between sound and flow on the aerodynamic characteristics of bluff bodies are commonly encountered in engineering practices, such as wind turbine blades and heat exchanger compressors. This study experimentally investigates the effects of sound over a broad range of frequencies (0–400 Hz) and sound pressure levels (80–105 dB) on the streamwise wind pressures on a flat plate in both smooth and turbulent flows. Spectral analysis and proper orthogonal decomposition (POD) are employed to explore the effects of sound on the aerodynamic forces acting on the flat plate. The results show that the effects of sound on wind pressure distributions and separation bubble behaviors over the flat plate depend on both sound frequency and sound pressure level. Furthermore, the findings highlight the role of acoustic resonance, which can increase the fluctuating wind pressure on the plate surface by over 400%. These effects can also be influenced by sound pressure levels. Additionally, the results demonstrate varying degrees and forms of attenuation of sound effects in turbulent flows, depending on the wind flow characteristics.

Wind loads on a square high-rise building under aerodynamic interference effects of a short building in close proximity

Although the interference effect of an equally high or higher building has been examined extensively, the interference effect of a short building in close proximity on the wind pressure of a high-rise building has not yet been investigated comprehensively and thoroughly. In view of the fact that a newly built wind-sensitive high-rise building is more likely to be close to neighboring shorter buildings, this research focuses on wind loads of a square high-rise building under the interference effect of a short building in close proximity. Wind pressure on the principal square building model is measured by wind tunnel test for a series of cases of interfering buildings with different heights and gap distances. In addition, computational fluid dynamics simulation is conducted for a few typical cases. Characteristics of wind flow and pressure on the principal building are then discussed in detail for three typical interfering configurations to uncover the mechanism of interference effect of a short building. Although a short interfering building in many cases tends to decrease wind loads on the high-rise building, especially for the dynamic component of wind loads, the interfering effect from a short building could induce damage to cladding structures from the increased tension caused by the asymmetrical wind pressure, channeling effect, and the wind-over-top flow over the short interfering building.

Numerical Study of Wind Flow Behavior Around High-Rise Buildings Using Computational Fluid Dynamics (CFD)

The development of civil construction technology in Indonesia is progressing along with the rise in high-rise building construction. The emergence of high-rise buildings has altered wind flow characteristics, leading to phenomena that can directly impact surrounding structures. One of the observable phenomena is the wind speed amplification caused by the narrowing of the wind flow section, known as the Venturi effect. This study aims to compare the outcomes of two Computational Fluid Dynamics (CFD) methods—Reynolds-Averaged Navier-Stokes (RANS) and Large Eddy Simulation (LES)—against experimental results. The study employs a model of four buildings of similar height and symmetrical positioning, with a 72 mm passage width, to verify numerical simulations against experimental data. The RANS method yields a maximum wind speed amplification of 14.9% along the passage's centerline, which remains below the experimental prediction of 25.5% in Zone A. Conversely, the LES results show a higher wind speed amplification, reaching 40.2%, surpassing the experimental findings. Nevertheless, LES identifies a similar location for wind speed amplification observed in Zone A. Additionally, CFD simulations were conducted to analyze the effects of passage width, revealing that a passage width of 54 mm produces the highest wind speed amplification, with a ratio value of passage width to building influence scale (L/S) of 0.481. Further research on building model scale may be necessary to verify CFD accuracy compared to the actual scale. However, such simulations demand exceedingly high computational resources with current technology.

Wind Flow Characteristics on a Vertical Farm with Potential Use of Energy Harvesting

The response to the climate emergency requires solutions that address multiple sustainability targets, which could be conducted by merging scientific research from areas that have traditionally evolved separately. This investigation presents advances in that direction by studying a building prototype designated for vertical farming, which enables the wind energy potential across built-up areas to be explored, in this case through the implementation of micro-wind turbines on the surface of the prototype. The study includes a parametric analysis consisting of varying locations of wind turbines across the building envelope, and the width of ventilation corridors. The effects of different widths of outdoor ventilation corridors, various locations, and additional wind angles on the capacity to harvest wind resources were investigated. The results showed that the 5 m wide outdoor corridor has the best ventilation effect, and the wind turbine placed on the roof has the best wind energy potential. The efficiency of wind turbines decreases significantly when multiple devices are placed at the same height on the façades, although overall, the potential for energy harvesting seems incremental.

The Impact of High-Rise Building Shapes on Wind Flow Characteristics and Energy Potential

In recent years, wind energy has become a potential source of low carbon energy. The shape of a building is a significant factor in aerodynamics, providing an opportunity for wind power control and wind energy proliferation. This research project aims to study the design of high-rise buildings and investigate how wind affects energy absorption by developing an aerodynamic optimization procedure (AOP) and using Computational Fluid Dynamics (CFD) in COMSOL Multiphysics. This study aimed to optimize the building shape for wind energy exploitation. Optimizing the building shape in the early stages of design enables the control of wind-induced loads and responses and reduces the energy demand in high-rise buildings, where resource consumption is higher than that in low-height buildings. This study used a three-dimensional CFD simulation of wind loading on tall buildings to optimize the building shape. This research will provide valuable insights for architects, engineers, and building developers to design and optimize high-rise buildings for wind energy exploitation, reduce the carbon footprint, and improve the energy efficiency of buildings.

Pressure Power Spectra of a ‘Z’ Shaped in Plan Tall Building under Transient Wind Environment

This study foresees the behavior of a ‘Z’ shaped in plan tall building under transient wind storms using unsteady Reynolds-averaged Navier Stokes (URANS) Computational Fluid Dynamics (CFD) technique. Numerical simulations are carried out using ANSYS - CFX, adopting length and velocity scales of 1:300 and 1:5, respectively. Surface streamlines are presented in the article to depict the wind flow characteristics and envisage the regions and nature of flow separations and vortex generations. The flow features also facilitate visualizing the wind pressure contours on building facets. The peak pressure coefficients concerning wind angles of 0° and 90° are presented to enable the cladding design of the building. Moreover, normalized wind pressure power spectra at three different sections along the altitude are offered for 0° to 150° wind at an interval of 30°. It is observed that towards the bottom portion of the building, the peak of the power spectra usually occurs in the low-frequency values. In contrast, at the top and main body of the building, the vortex shedding energy exaggerates at comparatively high reduced frequencies..

Assessment on natural ventilation and pollutant dispersion around sunken squares by transient simulation

Sunken square is a semi-open public space that has been gaining popularity in urban planning and designs. Its semi-open design is beneficial to ventilation of the connected underground spaces, but it is also subject to potential exposure to ground-level traffic pollutants. To evaluate the semi-open design’s influence on the balance between underground ventilation efficiency and the pollutant exposure, this study uses large eddy simulation (LES) to simulate turbulent wind flow characteristics and pollutant dispersion in a typical sunken square. The sunken square is connected to two indoor spaces with single-sided opening, and the design features of staircase and arcade are further tested for their influences on the wind flow field. The air change rate per hour (ACH, h−1) is adopted to quantify the ventilation efficiency of the two connected indoor spaces. Results show that the staircases amplify wind velocities for the indoor spaces but also bring higher pollutant concentrations inside together. Moreover, the design of the arcade at the opening prompts the vortex to shift towards the entrance, leading to a heightened concentration of pollutants. Meanwhile, the effective ACH is mostly contributed by the turbulent diffusion (ACHt), while the mean flow (ACHm) has much less effect on the ventilation of the indoor spaces. These findings of this study provide references for sunken square design.

Flow around single and two tandem rectangular cylinders with various single-side fairings

The shape of single-side wind fairing, which is the longitudinal triangular prism that tailors the outer side of a bridge deck, is key to the aerodynamic performances of double streamlined box girders used in long-span bridges. Uniform flow past single and double 4:1 rectangular cylinders with various single-side fairings are investigated using large-eddy simulation at a Reynolds number of 1.1 × 104. Various fairing nose angles and heights are compared. The wind loading and flow characteristics of the cylinders are discussed. The upstream fairing shows a larger reduction of mean drag and fluctuating lift on double cylinders than on a single cylinder. The fairing nose angle has a stronger influence on the wind loading than the nose height. By adding the fairing, sharpening the fairing nose, or lifting the fairing nose, the lateral recirculation zones are shortened while the rear recirculation zone barely changes, leading to different influences on the surface pressure. The upstream fairing is effective in reducing the vertical range and complexity of vortex structures around single and double cylinders.

A Generalization of Building Clusters in an Urban Wind Field Simulated by CFD

The urban climate has a critical influence on developing sustainable cities, and one important factor is the urban wind environment. Moreover, refining urban wind fields is required for the quantitative assessment of urban wind environments. Computational fluid dynamics (CFD) is a powerful tool for modeling the wind flow characteristics in urban areas. Although CFD has been widely used in various fields, its use for simulating urban wind fields has limitations because of the complexity of urban building models and the high computational workload. Accordingly, we consider the generalization parameters in the vertical and horizontal directions based on the CFD results and the building topology based on the state of the building nodes. We perform a two-dimensional generalization of building clusters, conduct spatial analysis in a geographic information system (GIS), and generate three-dimensional models. This generalization scheme is applied to Meiling Street in Jinjiang City, Fujian Province, China. The results indicate that the generalization decreases the number of buildings from 7003 to 3367 and the computation time from 11 h and 26 min to 10 h and 25 min. The computation efficiency is improved by 8.89%, with 1.85% changes in the average wind speed ratio. This scheme substantially improves the computational efficiency of urban wind field CFD simulations by reducing the geometric model’s complexity without compromising the accuracy. This strategy is suitable for simulating large-scale urban wind fields.

Research on the Characteristics of Urban Building Cluster Wind Field Based on UAV Wind Measurement

An innovative approach for measuring wind fields in urban building clusters using Unmanned Aerial Vehicles (UAVs) is presented. This method captures the distribution of wind fields within clusters. The results indicate that building architecture has a significant influence on wind flow characteristics at 15 m and 25 m height levels. Particularly, areas adjacent to the buildings and the wake section exhibit notable variations in wind speed and turbulence intensity compared to the incoming flow. The regions most affected include the areas flanking the buildings on either side and the intermediate section of the wake. The flow separation and convergence of incoming wind from the windward sides of the buildings notably amplify the wind load, resulting in a significant shift in wind speed and turbulence intensity within pedestrian pathways. The use of UAVs for wind measurements enables a flexible and efficient assessment of urban wind fields. These findings pave the way for further research into wind field measurements in urban architecture and a better understanding of the interference effects of buildings.

Improving the urban wind flow prediction efficiency of target area by considering its surrounding buildings impact

Rapid urbanization has caused various urban environmental challenges, including the emergence of urban heat island and air pollution. Urban wind flow is a crucial factor shaping the urban environment, which needs effective prediction and design. Computational fluid dynamics is commonly used for prediction and design of urban wind environment. However, high-accuracy simulation of wind flow, especially considering the layouts of full-scale and complex buildings, requires intensive computational resources. Typically, simulations simplify the surrounding building layouts (e.g., building layers) of target areas, potentially impacting simulation accuracy. It is imperative to determine appropriate building layers around different-scale target areas for effective wind flow simulation. This work explored the simulated wind flow characteristics of multi-scale (local, micro, and building-scale) target areas with different building layers defined as H, L, H/L, and L/H (H and L representing the vertical and horizontal maximum sizes of target area). The recommended building layers for local-scale, micro-scale, and building-scale target areas were at least 3L, 4H, and 5H, respectively, ensuing the relative errors between simulated and measured wind velocities remained below 20 %. This method largely reduced the calculation time by 73 % compared with full-scale simulation. This work can provide guidelines for fast prediction and design of urban wind environment, further promoting the sustainable development of urban cities.

Triple-lidar measurements of wind across a virtual rotor plane over a sea surface

An improved understanding of the spatiotemporal characteristics of the wind velocity field above the sea surface will benefit the design of modern offshore wind turbines. This study examines wind velocity data recorded on a bow-tie-like measurement pattern, approximately covering a rotor area diameter of about 70 m. The measurement data are obtained by triple continuous-wave Doppler lidars (short-range WindScanners). Two of the instruments are installed on a stable platform in the form of a suspension bridge deck, whereas the third is stationed on the ground nearby. Data from sonic anemometers installed above the bridge deck are used to validate the wind characteristics observed by the lidars. The lidar measurement data are explored in terms of wind flow mapping, mean flow characteristics and co-coherences. The results demonstrate the difference between the co-coherence at lateral and vertical separations and also differences from the coherence model in the IEC standard. The results further show the potential of lidar measurements to provide new insight into mean wind flow and turbulence characteristics applicable for offshore wind turbine design.

Combining Weather Station Data and Short-Term LiDAR Deployment to Estimate Wind Energy Potential with Machine Learning: A Case Study from the Swiss Alps

Wind energy potential in complex terrain is still poorly understood and difficult to quantify. With Switzerland’s current efforts to shift to renewable energy resources, it is now becoming even more crucial to investigate the hidden potential of wind energy. However, the country’s topography makes the assessment very challenging. We present two measurement campaigns at Lukmanier and Les Diablerets, as representative areas of the complex terrain of the Swiss Alps. A general understanding of local wind flow characteristics is achieved by comparing wind speed measurements from a near-surface ultra-sonic anemometer and from light detection and ranging (LiDAR) measurements further aloft. The measurements show how the terrain modifies synoptic wind for example through katabatic flows and effects of local topography. We use an artificial neural network (ANN) to combine the data from the measurement campaign with wind speed measured by weather stations in the surrounding area of the study sites. The ANN approach is validated against a set of LiDAR measurements which were not used for model calibration and also against wind speed measurements from a 25-meter mast, previously installed at Lukmanier. The statistics of the ANN output obtained from multi-year time series of nearby weather stations match accurately the ones of the mast data. However, for the rather short validation periods from the LiDAR, the ANN has difficulties in predicting lowest wind speeds at both sites, and highest wind speeds at Les Diablerets.

Effects of aerodynamic damping on freestanding bridge tower under the joint action of wind and wave loads

This study uses a time-domain simulation to investigate the effect of aerodynamic damping on a freestanding bridge tower under the joint action of wind and wave loads. The physical model of the bridge tower, which has been tested in laboratory, is numerically reconstituted considering structural nonlinearities obtained from free oscillation tests. Random wind fields are generated using the harmonic superposition method, and the wind flow characteristics, such as mean wind velocity and turbulence intensity, are identified based on the data collected in the laboratory. The wave loads measured at the bottom of the foundation during the experimental model tests are used for the simulation. The dynamic responses of the tower under the joints action of wind and wave loads are successfully simulated. A clear reduction in structural vibration in the wave-controlled region is confirmed by simulation results. Further numerical investigation indicates that an increase in the mean wave velocity produces additional aerodynamic damping in the structural motion system, which significantly dampens the responses of the wave-induced vibration. A simple method for determining the dynamic responses of a bridge tower under the joint action of wind and wave loads, using the data obtained from wind- and wave-only cases, is proposed.

Study on Dust Migration Law and Spray Dust Suppression Technology in Fully Mechanized Mining Face

To effectively solve the problem of high dust concentration during coal cutting and frame shifting in fully mechanized mining faces, based on the theory of gas–solid two-phase flow, a geometric model of a fully mechanized mining face was established by using COMSOL numerical simulation software. Simulations were performed for the movement characteristics of wind flow and the law of dust diffusion. Results show that the air flow at the junction of the working face, the air inlet, the hydraulic support moving area, and the vicinity of the shearer has accelerated movement, and the maximum wind speed zone of about 3 m/s can be formed. Under the influence of wind flow, dust particles above 35 μm settle faster, while dust particles below 35 μm are very vulnerable to the influence of wind flow, and the settling speed is slower. Using a custom experimental platform, the atomization characteristics and wind resistance of a pressure fan nozzle, a supersonic nozzle, and an ultrasonic nozzle were tested, and the nozzle that was suitable for the scheme was selected and applied in the field. Comparing the dust concentration before and after the application of the dust removal scheme at the sampling point, results show that the dust removal efficiency of the proposed scheme exceeds 85%, and the treatment effect is good.

IONIC WIND FLOW CHARACTERISTICS OF A MAGNETIC-FIELD-ENHANCED SOLID-STATE FAN AND ITS PERFORMANCE IN LIGHT-EMITTING DIODE COOLING APPLICATIONS

Solid-state fans (SSFs) have distinct advantages over traditional cooling fans in the thermal management of high-power electronics. In this work, a magnetic-field-enhanced SSF is proposed, and the physical model of negative corona discharge superimposed by an electromagnetic field is established. A computational model is used to calculate and analyze the effect of the magnetic field on the ionic wind distribution. The magnetic flux density and permanent magnet position distribution in the SSF are optimized experimentally, and the optimized SSF is applied to LED chip cooling. The findings show that adding a magnetic field encourages electrons to collide with neutral gas molecules and enhances the driving force of charged particles. The ionic wind velocity and mean driving force at the SSF's outlet will grow as magnetic flux density rises, and the ionic wind flow distribution will show apparent divergence. When the permanent magnet spacing is 15 mm, the highest ionic wind velocity is 2.82 m/s, and the mean driving force of SSF increases by 30.2%. The magnetic-field-enhanced SSF has a better LED-chip cooling effect, the maximum junction temperature drop is 11.6°C, and the cooling efficiency is higher. This research introduces a novel way of improving the cooling of electronics.

Study on dust control technology of mobile spray combined with full-section fog curtain in return airway of header working face.

For the problem of coal dust pollution in the return air lane of the comprehensive mining working face of soft rock mines.Based on the principle of supersonic siphon pneumatic atomization dust control, mobile vehicle-mounted pneumatic spraying combined with full-section fog curtain dust control technology is proposed to address the coal dust pollution problem in the return air tunnel of the comprehensive mining working face of soft rock mines. This technology has a wider spraying range, stronger wind resistance and lower energy consumption.Using the k-ε turbulence module and the fluid flow particle tracking module of COMSOL simulation software, a three-dimensional numerical model of the return air tunnel was established. The effect of wind flow characteristics on the diffusion range of coal dust and fog droplets was analysed, and the dust transport pattern and dust control effect of the new technology were obtained for different cross-sectional return airways. The results show that the velocity of the wind flow is continuously decayed by the slope, and the dust of different particle sizes is distributed differently by the inertial force. Coal dust with particle sizes larger than 6.5 μm accumulates below the structure at a lower velocity, and coal dust with particle sizes smaller than 4.5 μm is mostly suspended above the structure at a higher velocity. The device effectively stops the transport of dust and covers the whole section of the roadway, and the dust removal efficiency reaches 96.53%~97.93%, which provides relevant theoretical support and treatment means for the control of dust pollution in the return airway of coal mines.

Wind-flow dynamics and spore-like particle dispersal over agroforestry systems: Impact of the tree density distribution

Agroforestry systems associating trees with crops are gaining a growing interest due to their environmental benefits in a context of climate change and biodiversity loss. Still, the impact of trees on the wind dynamics within agroforestry systems remains poorly understood despite the key role played by the wind in energy and mass exchanges, including disease and pest propagation. Here, we present the first detailed analysis of the wind dynamics over agroforestry systems, combining in situ measurements and instantaneous airflow simulations, with a numerical application on spore-like particle dispersion from an infection point source at crop top. Simulations reproduce remarkably well most characteristics of the turbulent wind flow within the agroforestry system. Simulations reveal the presence of two inflection points on the mean wind velocity profile, at crop and tree tops, both inducing the development of mixing-layer type eddies, controlling most of the turbulent exchanges within the agroforestry system. Relative to the local wind, the turbulence at the crop scale is more intense and intermittent in presence of trees. With increasing tree density, the turbulence at crop top becomes dominated by tree-scale motions developing at tree top. The presence of trees has a different impact on particle dispersion according to the particle size and the wind intensity. Trees accentuate the vertical and transversal dispersal of submicron spores while they enhance the short-range deposition of coarser spores on crops, the more as the wind is low, and thus limit the long-range dispersal of coarse spores. Finally, a simple parameterization of the mean wind velocity vertical profile is proposed for agroforestry systems, depending only on the foliage densities and heights of the tree and crop layers. This parameterization leads to an indication of the agroforestry system efficiency to limit spore propagation through an estimation of the Rouse number at crop top.

Study on coal dust diffusion law and new pneumatic spiral spray dedusting technology at transfer point of mine cross roadway.

In order to solve the problem of coal dust pollution at the transfer point, a three-dimensional numerical model of wind flow-coal dust at the loading point of underground rubber run was established by computational fluid dynamics (CFD) discrete particle model and finite element method and k-ε turbulence model, and the coal dust diffusion pollution phenomenon caused by the coal flow transfer under the intersection of wind flow in the cross tunnel was studied. Based on the simulation results of wind flow velocity contour, pressure contour and isochronous flow vector distribution, the influence mechanism of wind flow and coal dust characteristics on the distribution of wind flow and coal dust diffusion in the roadway is analysed, and a dust control and reduction system and treatment scheme with new pneumatic screw spray technology as the core is proposed to suppress coal dust pollution at the reloading point. The results of the study show that the wind flow distribution is mainly influenced by the intersection of tape traction and cross-roadway wind flow, showing a complex multi-layer distribution along the roadway and in the normal direction; the diffusion of coal dust of different particle sizes is influenced by the roadway wind flow, and coal dust with particle sizes in the range of 10μm~20μm is more easily diffused, and the dust with particle sizes in the range of 20μm~45μm is mainly collected and suspended near the vortex wind flow at the cross-roadway. The coal dust in the range of 20 μm~45 μm is more likely to gather in the vortex; the treatment system effectively controls the coal dust inside the dust cover, and the spiral-shaped transported droplet particle group formed by the pneumatic spiral spray combines with it efficiently, which verifies the dust control and reduction effect of the pneumatic spiral spray system at the transfer point, and the dust removal efficiency reaches 89.35%~93.06%, which provides relevant theoretical support for the treatment of dust pollution at the coal transfer point in underground coal mines It provides the theoretical support and means to control dust pollution at underground coal transfer points.