Wind Load Characteristics Research Articles

Extreme combination of wind effects and analysis of wind load characteristics for low-rise buildings

ABSTRACT Based on transcendental probability theory, the probability density functions of two non-Gaussian scalar sums of wind effects are derived from the relationship between the probability density of the sum of random variables and the joint probability density function of sub-random variables by Hermite polynomial transformation. The extreme values of the two non-Gaussian wind effects are derived from the probability density function of the two components of the scalar sum, and then the equation of the combined coefficients of the two uncorrelated non-Gaussian wind effects is derived. Based on the POD decomposition of the covariance matrix of the fluctuating non-Gaussian wind effect after variance normalization, the combined extremum equations for the positive and negative correlation of the two non-Gaussian wind effect components are derived, respectively. The extreme value combination equations of the multi-component non-Gaussian fluctuating wind effect are derived from the two-component combination, and the influence coefficients of the non-Gaussian extreme value are verified by the extreme value probability transformation method. The wind load characteristics and the combination of wind load effect components of low-rise buildings under different eave heights and roof slopes are investigated by using the test data of low-rise buildings in NIST database.

Critical Wind Direction Angles and Edge Module Vulnerability in Fixed Double-Row Photovoltaic (PV) Arrays: Analysis of Extreme Wind Conditions Based on CFD Simulation

Fixed double-row photovoltaic (PV) arrays are susceptible to wind-induced damage, while their wind load characteristics remain inadequately investigated. This study employs computational fluid dynamics (CFD) simulations to systematically analyze wind load behavior under varying operational conditions, aiming to identify critical scenarios and structural vulnerabilities. First, the validity of the CFD methodology was verified through direct comparison between wind tunnel pressure measurements of an isolated PV module and corresponding numerical simulations. Subsequently, scaled PV array models were constructed to replicate practical engineering configurations, enabling a systematic evaluation of wind direction effects on mean net wind pressure coefficients and three-component force coefficients. Finally, surface wind pressure distribution patterns were examined for four representative wind angles (0°, 45°, 135°, 180°). Results demonstrate that edge-positioned modules exhibit maximum mean net wind pressure coefficients and three-component force coefficients under oblique wind angles (45° and 135°), which are identified as the most critical operational conditions. In contrast, minimal wind loads were observed at a 90° wind angle, indicating an optimal orientation for array installation. Additionally, significantly higher surface wind pressure coefficients were recorded for edge modules under oblique winds (45°/135°) compared to both interior modules and other wind angles. It was found through the study that under upwind conditions (0–90°), the lower-row components are capable of withstanding greater wind loads, whereas under downwind conditions (90–180°), an increase in the loads exerted on the upper-row components was observed.

CFD simulation and wind loads evaluation on wind turbine blades in mountainous terrain under thunderstorm downbursts

ABSTRACT Downbursts are serious threat to the structural safety of wind turbines during thunderstorm season. This work develops and validates a CFD based numerical model to analyze the wind load characteristics of wind turbine blades in mountainous terrain under thunderstorm downbursts. Additionally, the impacts of wind turbine installation position and operation state are investigated on the blade loading characteristics of wind turbines, and the distribution characteristics of wind turbine blade loading along the spanwise direction of the blade are numerically analyzed in detail. The results show that blade loads on the windward side of the mountain are reduced by the downburst, while the blade loads on the leeward side of the mountain may reach up to 2.9 times larger than that in the flat terrain. Besides, the rotating blade load is larger than the stationary one in the downburst, and the difference in horizontal thrust is up to 3.9 times in the flat terrain and 4.3 times in the mountainous terrain. The middle and tip regions of the blade are the main loaded and wind-sensitive regions under downburst. This work may provide theoretical guidance for evaluation and optimization of the wind turbine blades under downburst.

Experimental study on wind load characteristics of rectangular high-rise buildings with varied aspect ratios

The wind load is one of the predominant factors for high-rise buildings and it has been found that the aspect ratio of the section affects the wind-induced forces on buildings significantly. In this paper, simultaneous wind pressure tests were conducted for three rectangular tall buildings in the wind tunnel, with different aspect ratios of 1:1, 1.5:1, and 2:1 (named Model I/II/III). The characteristics of wind pressure on buildings under different wind azimuths were analyzed and the following conclusions were obtained. When the longer sides of the buildings (Side I/III) are perpendicular to the wind, the variation tendency of the most unfavorable wind pressure coefficient along increasing aspect ratio has a critical value on the windward/leeward/top facades, and it was found the critical ratio equals 1.5 (Model II). Moreover, when the shorter sides of the buildings (Side II/IV) are perpendicular to the wind, it can be found that Model II presents the most unfavorable wind pressure on the crosswind side. Referring to the leeward side, the larger the aspect ratio, the more favorable the negative pressure appears. Furthermore, the horizontal correlation coefficients at points on the windward/leeward side are generally higher in Model II. The power spectrum of the measuring points on the axis of the crosswind and leeward sides gradually decreases in the low frequency range, while the energy in the high frequency range gradually increases. The comprehensive experimental data provided in this work can be used for further wind resistance studies.

Numerical investigation of wind load on flexible photovoltaic arrays considering the impact·of water surface and·shore height·difference

Abstract Photovoltaic panels are commonly utilized in settings like fish ponds and reservoirs. Water level changes in these scenarios can cause height difference between the water surface and the shoreline, which may lead to changes in the wind load characteristics, thereby raising the likelihood of harm to the photovoltaic panels. To address the issue, this study undertakes a numerical study of flexible photovoltaic arrays subjected to wind loads considering the impact of height difference between the water surface and shore. Firstly, this study establishes a model for a single-row flexible photovoltaic frame without height difference to calculate the wind pressure coefficient, which is then compared with existing literature to verify the accuracy of the simulation. Next, three types of flexible photovoltaic arrays models with height difference are used to study how these height difference affect wind pressure coefficients. Finally, flexible photovoltaic arrays with wind barriers are established to explore the effect of wind barriers on reducing wind pressure coefficients. The results show that under a 180° wind direction, the height difference can double the surface suction of the downstream photovoltaic panels. Adding wind barriers can reduce the absolute value of the lift coefficient on flexible photovoltaic arrays to below 0.2.

Impact of corner optimization measures on the interference effects between two square section buildings

Wind-induced interference effects occur between high-rise twin buildings. To elucidate the impact of aerodynamic optimization measures on the interference effects between high-rise buildings, large eddy simulations (LES) were conducted to analyze the wind load characteristics of buildings with varying spacing. The simulation results were compared with experimental data and previous studies to validate the method’s accuracy. To investigate the influence of various aerodynamic corner optimizations on interference effects between high-rise buildings, LES was employed to simulate wind load characteristics. Simulation results were compared with experimental data and previous studies to ensure the method’s accuracy. Three corner treatments—chamfered, rounded, and recessed—were applied to the model, with a corner modification rate of 10%. Under wind field conditions corresponding to a Reynolds number (Re) of 22,000, 10 simulated schemes with spacing ratios (B/L) ranging from 1.2 to 8 were considered, where B represents the center-to-center distance between two square cylinders, and L denotes the side length of each square cylinder. The aerodynamic coefficients, flow field mechanisms, and vorticity of the two side-by-side square cylinders under three corner treatments were compared. Additionally, peak factors were calculated based on predefined measurement points to further assess differences in interference factors. Using the Lorentz function, the peak fitting curve of the wind pressure probability density was compared with the Gaussian fitting curve. The analysis indicates that the wind pressure shielding effect is most pronounced for the rounded corner square cylinder, while the amplification effect is strongest for the chamfered corner square cylinder. At critical spacing, the adjacent facades of the recessed corner square cylinders exhibited a bimodal distribution in wind pressure probability density.

Characteristics of wind load on high-voltage disconnect switch system in substation

Ensuring high-voltage disconnect switch system safety is essential for the stable operation of the power system. A method for wind force tests to determine the wind load characteristics of the whole and the segments of the disconnect switch system was developed. Through this method, the distributions of aerodynamic coefficients for both the whole structure and its segments were determined, along with the skewed wind load coefficient relative to wind direction. The two-parameter model for wind load was used to predict wind load distribution along the structure's height. The study also considered the effect of different operating states of the disconnect switch system, namely, the switching-off and switching-on states, on wind force coefficients. Comparisons and analyses were performed to examine how these states influence the mean, fluctuating, and peak wind force coefficients, as well as the skewed wind load coefficient of the structure. The results indicate that the calculations of the two-parameter model are in good agreement with the measurements from the segment models. The most critical wind directions for the drag and skewed wind load coefficients for each segment of the structure were found to be 60° and 120°, respectively. Additionally, the mean wind load on the switch and insulator segments was higher than that on the steel columns. The switching-on state was identified as more detrimental to mean and fluctuating wind loads, with a pronounced effect on crosswind and torsional wind loads, especially on the torsional response of the structure.

The effect of ribs on wind load characteristics of cylindrical structures in streamwise sinusoidal flow: A numerical investigation

This study examines the aerodynamic effects of streamwise sinusoidal flow on circular and ribbed circular cylinders using large-eddy simulation. Six cases with varying oscillation frequencies are analyzed to assess their impact on aerodynamic forces and wake dynamics. The results reveal that increasing the oscillation frequency leads to a rise in both drag and lift coefficients at low frequencies, followed by a sharp decline at higher frequencies. Notably, ribbed cylinders (RC) exhibit higher mean drag and lower root mean square lift fluctuations compared to circular cylinders (CC) at high frequencies. The Strouhal number for RC is also narrower, indicating less efficient aerodynamic characteristics under the same flow conditions. Streamwise sinusoidal flow significantly alters the wake structure, particularly for frequencies fu/fst exceeding 1, with peak wind pressure fluctuations occurring at fu/fst = 2. RC shows complex pressure fluctuations, especially on the windward side, though the trend mirrors CC. For both CC and RC, vortex shedding is suppressed at higher frequencies, with complete cessation observed at fu/fst = 2, corresponding to peak aerodynamic coefficients. Dynamic mode decomposition analysis highlights that low-frequency flow results in more coherent vortex shedding, whereas higher frequencies cause the vortex street to become less organized. RC shows weaker pulsations, contributing to its reduced lift fluctuations and greater aerodynamic stability. Overall, the study demonstrates that streamwise sinusoidal flow and ribbed configurations significantly influence wind load behavior. RC offers superior aerodynamic stability in high-turbulence flows, suggesting its potential for optimizing wind-resistant structural designs.

Effects of side ratio on wind load characteristics on high-rise building

This study investigates the impact of varying side ratios (SR) on wind loads in high-rise buildings using wind tunnel tests and large eddy simulations. It assesses surface wind load by analyzing static three-component force coefficients and shape factors across different SRs. The results show that the model with D/B = 0.5 exhibits the largest mean and r.m.s drag forces, while the model with square cross section (D/B = 1) experiences the lowest torque. Meanwhile, the model with D/B = 0.5 reveals strong vertical but relatively weak horizontal wind pressure correlation. In addition, models with large SRs exhibit altered wind pressure mechanisms due to the occurrence of flow reattachment and secondary separation, resulting in lower side-surface correlation compared to small SR models.

Dynamic Analysis of Slender Buildings under Wind Loading

This dissertation project aims to understand and compare methods that simulate the dynamic characteristics of atmospheric wind loads acting on slender structures, with a focus on NBR 6123 and the Synthetic Wind Method. The amount of research conducted on this topic since the 1960s has led to significant advancements in understanding the dynamic behavior of wind. This progress has facilitated the development of methodologies for quantifying its impact on buildings and the continuous refinement of these methodologies up to the present day. In this context, it is possible to encounter two key approaches: NBR 6123 (2023), developed by the Brazilian Association of Technical Standards, and the Synthetic Wind Method, initially proposed by Franco (1993). The Brazilian standard provides two methods to determine maximum values of variables such as acceleration, displacement, and forces for structures subjected to wind, without describing how these values vary over time. Despite advances in wind engineering studies and methodologies, the procedure described in the 1988 version of the standard remained unchanged in its 2023 update. On the other hand, the Synthetic Wind Method, first published in 1993 and subsequently refined until 2014, works by decomposing the fluctuating component of wind into harmonic functions. This approach not only allows to obtain absolute maximum values but also provides the structural response over time. To address this, a comparative study is planned between NBR 6123 (2023) and the most updated version of the Synthetic Wind Method. Additional relevant methods may also be included in the analysis to identify the limitations, advantages, and disadvantages of each approach.

Investigation of wind load characteristics of cantilevered scaffolding of a high-rise building based on field measurement

Investigation of wind load characteristics of cantilevered scaffolding of a high-rise building based on field measurement

Simulation and Field Measurement of Wind-Induced Vibration Response Characteristics of the Lightning Rod

Abstract Studying the wind-induced vibration model and response characteristics of lightning rods is crucial for achieving their rational design and wind stability. To address the current shortcomings in considering on-site wind load characteristics and the lack of differentiated considerations in the design phase of lightning rods, it is essential to establish an effective simulation model that accurately reproduces the wind induced vibration response of lightning rods and extracts key parameters for analysis. In this study, a 330kV independent lightning rod in Ningxia province, China, was identified as the subject of analysis. Building upon the structural vibration model, the response of the lightning rod to wind induced vibrations was calculated, and the simulation results were systematically validated through on-site measurements. The results indicate that the simulation model developed in this study can effectively replicate the vibration process of the lightning rod under wind load, providing comprehensive mechanical data. The research findings contribute to a deeper understanding of the wind induced characteristics of on-site lightning rods, facilitating the simulation analysis of lightning rod wind induced responses. Furthermore, the vibration law and characteristic parameters of the lightning rod structure hold great significance for the differentiated design and structural health monitoring of independent lightning rods.

Study on wind load characteristics of gable roof under tornado

This research simulates the behavior of a tornado on a double-slope roof using the Ward tornado generator and the \\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$SS{T_{k - \\omega }}$$\\end{document} turbulence model. The effects of different ground roughness, slope angle, and wind field position on the tornado load characteristics of gable roofs were studied. The tornado-generating device established the tornado field under various working conditions, and the simulation results were compared with the experimental data to verify the reliability of the simulation results. The wind pressure distribution of gable roofs with four different slope angles was analyzed to find the most unfavorable roof condition of the tornado field. The gable roof’s aerodynamic and wind pressure characteristics at various places in the tornado field were explored by comparing the wind pressure coefficients at five distinct positions on smooth and rough ground. The lift-drag and wind pressure coefficients of five kinds of ground roughness were calculated to determine the influence of different ground roughness on the aerodynamic force and partial pressure distribution of the gable roof. The ground roughness reduces the vortex ratio because the ground roughness reduces the maximum tangential wind speed and the radius of the vortex core. Therefore, the gable roof’s suction increases as the updraft increases.

Research on Wind Load Characteristics of High-Rise Building Sail-Shaped Tower Crown

Research on Wind Load Characteristics of High-Rise Building Sail-Shaped Tower Crown

Investigation of the wind loads and flow patterns of a high-rise building under twisted wind flows based on LES

Investigation of the wind loads and flow patterns of a high-rise building under twisted wind flows based on LES

The balance issue of the proportion between new energy and traditional thermal power: An important issue under today's low-carbon goal in developing countries

The balance issue of the proportion between new energy and traditional thermal power: An important issue under today's low-carbon goal in developing countries

The Impact of Installation Angle on the Wind Load of Solar Photovoltaic Panels

In order to explore the wind load characteristics acting on solar photovoltaic panels under extreme severe weather conditions, based on the Shear Stress Transport (SST) κ-ω turbulence model, numerical calculations of three-dimensional incompressible viscous steady flow were performed for four installation angles and two extreme wind directions of the solar photovoltaic panels. The wind load characteristics on both sides of the photovoltaic panels were obtained, and the vortex structure characteristics were analyzed using the Q criterion. The results indicate that, under different installation angles, the windward side pressure of the solar photovoltaic panel is generally higher than the leeward side. The leeward side is prone to forming larger vortices, increasing the fatigue and damage risk of the material, which significantly impacts the solar photovoltaic panel. As the installation angle increases, the windward side pressure of the solar photovoltaic panel also gradually increases. Therefore, optimal installation methods include installing the panel facing the wind at angles of 30° and 45°, or installing it facing away from the wind at a 60° angle, to minimize the impact of wind load on the solar photovoltaic panel.

Partitioning of wind pressure coefficients on a tall building under interference effect: A cluster analysis approach

Partitioning of wind pressure coefficients on a tall building under interference effect: A cluster analysis approach

Experimental study of turbulent inflow on the aerodynamic performance of a wind turbine with Gurney flaps

Nowadays, wind turbines operate within complex inflow environments. Meanwhile, installing Gurney flaps on existing wind turbines could enhance wind energy efficiency. However, limited research has been conducted on the variation of aerodynamic characteristics of a wind turbine equipped with Gurney flaps under turbulent inflow conditions. Hence, wind tunnel test comparisons were made between the output power, wind load, and wake characteristics of a model wind turbine with and without Gurney flaps. The results demonstrated a correlation between the additional power increase in the wind turbine equipped with Gurney flaps and the aerodynamic variation of the corresponding airfoil. Gurney flaps could be effective at higher tip speed ratios, and the power enhancement efficiency initially increased but then decreased as turbulence intensity increased from a low value to 19.0%. Installing Gurney flaps resulted in significant pulsation peaks within the original inertial sub-range. The time-averaged thrust coefficient shifts upward, but the difference decreases slightly under turbulent conditions. Wake analysis revealed that the presence of additional wake velocity deficits primarily concentrated within the near-wake region, which extends along the spanwise direction. These findings could enhance a better understanding of the aerodynamic performances of wind turbines installing Gurney flaps under varying turbulent flow conditions.

Experimental study on wind load characteristics of rooftop canopies of low and medium rise buildings

Experimental study on wind load characteristics of rooftop canopies of low and medium rise buildings