The study of unsteady aerodynamic phenomena in wind tunnels is supported by gust-generating devices capable of generating adjustable magnitude and periodicity velocity fluctuations in a flowfield. Gusts are typically generated actively by introducing moving vanes to direct the flow, or passively by tailoring the boundary layer growth and shape in the tunnel. The flow facility used here is a student-built closed-return low-speed wind tunnel, with a test section size of 750 mm × 750 mm and a maximum speed of 25 m/s. A two-vane gust generator utilizing NACA0018 airfoil sections of 150 mm chord length was designed and installed upstream of the test section. The flowfield was mapped with the installed vanes with and without gust actuation, utilizing a hot wire system. The tunnel with gust vanes exhibits a spatially uniform baseline turbulence intensity of 5%, with a steady state velocity deficit of 1 m/s in the vane–wake region. Upon introducing the gusting conditions at vane deflection angles of up to ±45°, velocity differences of up to 4 m/s were attained at 18 m/s freestream velocity at oscillation frequencies ranging between 1 Hz and 2 Hz.
{"title":"Design, Construction and Evaluation of an Oscillating Vane Gust Generator for Atmospheric Flow Simulation","authors":"Aaron French, W. Friess, A. Goupee, K. Berube","doi":"10.3390/wind1010004","DOIUrl":"https://doi.org/10.3390/wind1010004","url":null,"abstract":"The study of unsteady aerodynamic phenomena in wind tunnels is supported by gust-generating devices capable of generating adjustable magnitude and periodicity velocity fluctuations in a flowfield. Gusts are typically generated actively by introducing moving vanes to direct the flow, or passively by tailoring the boundary layer growth and shape in the tunnel. The flow facility used here is a student-built closed-return low-speed wind tunnel, with a test section size of 750 mm × 750 mm and a maximum speed of 25 m/s. A two-vane gust generator utilizing NACA0018 airfoil sections of 150 mm chord length was designed and installed upstream of the test section. The flowfield was mapped with the installed vanes with and without gust actuation, utilizing a hot wire system. The tunnel with gust vanes exhibits a spatially uniform baseline turbulence intensity of 5%, with a steady state velocity deficit of 1 m/s in the vane–wake region. Upon introducing the gusting conditions at vane deflection angles of up to ±45°, velocity differences of up to 4 m/s were attained at 18 m/s freestream velocity at oscillation frequencies ranging between 1 Hz and 2 Hz.","PeriodicalId":51210,"journal":{"name":"Wind and Structures","volume":null,"pages":null},"PeriodicalIF":1.6,"publicationDate":"2021-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81318489","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Y. Uematsu, Tetsuo Yambe, Tomoyuki Watanabe, Hirokazu Ikeda
The present paper proposes a measure for improving the wind-resistant performance of photovoltaic systems and mechanically attached single-ply membrane roofing systems installed on flat roofs by combining them together. Mechanically attached single-ply membrane roofing systems are often used in Japan. These roofing systems are often damaged by strong winds, because they are very sensitive to wind action. Recently, photovoltaic (PV) systems placed on flat roofs have become popular. They are also often damaged by strong winds directed onto the underside, which cause large wind forces onto the PV panels. For improving the wind resistance of these systems, we proposed to install PV panels horizontally with gaps between them. Such an installation may decrease the wind forces on the PV panels due to the pressure equalization effect as well as on the waterproofing membrane due to the shielding effect of the PV panels. This paper discusses the validity of such an idea. The pressure on the bottom surface of a PV panel, called the “layer pressure” here, was evaluated by a numerical simulation based on the unsteady Bernoulli equation. In the simulation, the time history of the external pressure coefficients, measured at many points on the roof in a wind tunnel, was employed. It was found that the wind forces, both on the PV panels and on the roofing system, were significantly reduced. The reduction was large near the roof’s corner, where large suction pressures were induced in oblique winds. Thus, the proposed method improved the wind resistance of both systems significantly.
{"title":"The Benefit of Horizontal Photovoltaic Panels in Reducing Wind Loads on a Membrane Roofing System on a Flat Roof","authors":"Y. Uematsu, Tetsuo Yambe, Tomoyuki Watanabe, Hirokazu Ikeda","doi":"10.3390/wind1010003","DOIUrl":"https://doi.org/10.3390/wind1010003","url":null,"abstract":"The present paper proposes a measure for improving the wind-resistant performance of photovoltaic systems and mechanically attached single-ply membrane roofing systems installed on flat roofs by combining them together. Mechanically attached single-ply membrane roofing systems are often used in Japan. These roofing systems are often damaged by strong winds, because they are very sensitive to wind action. Recently, photovoltaic (PV) systems placed on flat roofs have become popular. They are also often damaged by strong winds directed onto the underside, which cause large wind forces onto the PV panels. For improving the wind resistance of these systems, we proposed to install PV panels horizontally with gaps between them. Such an installation may decrease the wind forces on the PV panels due to the pressure equalization effect as well as on the waterproofing membrane due to the shielding effect of the PV panels. This paper discusses the validity of such an idea. The pressure on the bottom surface of a PV panel, called the “layer pressure” here, was evaluated by a numerical simulation based on the unsteady Bernoulli equation. In the simulation, the time history of the external pressure coefficients, measured at many points on the roof in a wind tunnel, was employed. It was found that the wind forces, both on the PV panels and on the roofing system, were significantly reduced. The reduction was large near the roof’s corner, where large suction pressures were induced in oblique winds. Thus, the proposed method improved the wind resistance of both systems significantly.","PeriodicalId":51210,"journal":{"name":"Wind and Structures","volume":null,"pages":null},"PeriodicalIF":1.6,"publicationDate":"2021-11-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72733624","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Md. Yah-Ya Ul Haque, Jakir Hasan, M. Islam, Md. Rabiul Islam
The introduction of doubly fed induction generators (DFIGs) has facilitated the utilization of wind energy to a great extent and constituted distributed generation (DG) systems in remote places. Therefore, long transmission lines are required to interconnect with the utility grid and, consequently, different short-circuit faults interrupt this transmission. Use of different fault current limiters (FCLs) minimizes the effect of faults and allows normal operation with minimum interruption in power flow. In this study, a series-parallel resonance-type fault current limiter (SPRFCL) is presented for enhancing the low-voltage ride-through (LVRT) capability of DFIG-based wind farms. The SPRFCL preserves the nominal voltage and power quality within the permissible limit during normal operation and during disturbances irrespective of the type of fault. The effectiveness of the proposed SPRFCL is validated by simulating both symmetrical and asymmetrical faults. Alongside the SPRFCL, two state-of-the-art FCLs—the parallel resonance-type fault current limiter (PRFCL) and the capacitive bridge-type fault current limiter (CBFCL)—are considered to investigate and compare the relative performances. Several graphical and numerical studies assure the efficacy of the proposed SPRFCL in wind farm application in multiple aspect. Moreover, the stunning total harmonic distortion (THD) values with the proposed technique signifies the excellency over its competitors. Additionally, the sub-synchronous resonance (SSR) analysis confirms the supremacy of SPRFCL for series compensated lines.
{"title":"Low-Voltage Ride through Capability Augmentation of DFIG-Based Wind Farms Using Series-Parallel Resonance-Type Fault Current Limiter","authors":"Md. Yah-Ya Ul Haque, Jakir Hasan, M. Islam, Md. Rabiul Islam","doi":"10.3390/wind1010002","DOIUrl":"https://doi.org/10.3390/wind1010002","url":null,"abstract":"The introduction of doubly fed induction generators (DFIGs) has facilitated the utilization of wind energy to a great extent and constituted distributed generation (DG) systems in remote places. Therefore, long transmission lines are required to interconnect with the utility grid and, consequently, different short-circuit faults interrupt this transmission. Use of different fault current limiters (FCLs) minimizes the effect of faults and allows normal operation with minimum interruption in power flow. In this study, a series-parallel resonance-type fault current limiter (SPRFCL) is presented for enhancing the low-voltage ride-through (LVRT) capability of DFIG-based wind farms. The SPRFCL preserves the nominal voltage and power quality within the permissible limit during normal operation and during disturbances irrespective of the type of fault. The effectiveness of the proposed SPRFCL is validated by simulating both symmetrical and asymmetrical faults. Alongside the SPRFCL, two state-of-the-art FCLs—the parallel resonance-type fault current limiter (PRFCL) and the capacitive bridge-type fault current limiter (CBFCL)—are considered to investigate and compare the relative performances. Several graphical and numerical studies assure the efficacy of the proposed SPRFCL in wind farm application in multiple aspect. Moreover, the stunning total harmonic distortion (THD) values with the proposed technique signifies the excellency over its competitors. Additionally, the sub-synchronous resonance (SSR) analysis confirms the supremacy of SPRFCL for series compensated lines.","PeriodicalId":51210,"journal":{"name":"Wind and Structures","volume":null,"pages":null},"PeriodicalIF":1.6,"publicationDate":"2021-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81236993","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Wind energy is crucial in German energy and climate strategies as it substitutes carbon-intensive fossil fuels and achieves substantial greenhouse gas (GHG) reductions. However, wind energy deployment currently faces several problems: low expansion rates, wind turbines at the end of their service life, or the end of remuneration. Repowering is a vital strategy to overcome these problems. This study investigates future annual GHG payback times and emission savings of repowered wind turbines. In total, 96 repowering scenarios covering a broad range of climatological, technical, economic, and political factors affecting wind energy output in 2025–2049 were studied. The results indicate that due to more giant wind turbines and geographical restrictions, the amount of repowerable sites is reduced significantly. Consequently, in most scenarios, emission savings will dramatically diminish compared to current savings. Even in the best-case scenario, the highest emission savings’ growth is at 11%. The most meaningful drivers of GHG payback time and emission savings are wind turbine type, geographical restrictions, and GHG emissions. In contrast, climate change impact on the wind resource is only marginal. Although repowering alone is insufficient for achieving climate targets, it is a substantial part of the wind energy strategy. It could be improved by the synergies of different measures presented in this study. The results emphasize that a massive expansion of wind energy is required to establish it as a cornerstone of the future energy mix.
{"title":"Greenhouse Gas Savings Potential under Repowering of Onshore Wind Turbines and Climate Change: A Case Study from Germany","authors":"Leon Sander, Christopher Jung, D. Schindler","doi":"10.3390/wind1010001","DOIUrl":"https://doi.org/10.3390/wind1010001","url":null,"abstract":"Wind energy is crucial in German energy and climate strategies as it substitutes carbon-intensive fossil fuels and achieves substantial greenhouse gas (GHG) reductions. However, wind energy deployment currently faces several problems: low expansion rates, wind turbines at the end of their service life, or the end of remuneration. Repowering is a vital strategy to overcome these problems. This study investigates future annual GHG payback times and emission savings of repowered wind turbines. In total, 96 repowering scenarios covering a broad range of climatological, technical, economic, and political factors affecting wind energy output in 2025–2049 were studied. The results indicate that due to more giant wind turbines and geographical restrictions, the amount of repowerable sites is reduced significantly. Consequently, in most scenarios, emission savings will dramatically diminish compared to current savings. Even in the best-case scenario, the highest emission savings’ growth is at 11%. The most meaningful drivers of GHG payback time and emission savings are wind turbine type, geographical restrictions, and GHG emissions. In contrast, climate change impact on the wind resource is only marginal. Although repowering alone is insufficient for achieving climate targets, it is a substantial part of the wind energy strategy. It could be improved by the synergies of different measures presented in this study. The results emphasize that a massive expansion of wind energy is required to establish it as a cornerstone of the future energy mix.","PeriodicalId":51210,"journal":{"name":"Wind and Structures","volume":null,"pages":null},"PeriodicalIF":1.6,"publicationDate":"2021-09-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90391955","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-08-01DOI: 10.12989/WAS.2021.33.2.123
Debasish Kumar, S. Dalui
Corner modification plays an essential role in the reduction of the wind load and responses on tall buildings. The present study investigates the effectiveness of different corner modifications (chamfered, rounded, and recessed corners) to reduce the wind load on regular cross plan shaped tall buildings using the computation fluid dynamics technique. Here, ANSYS CFX is used to simulate the boundary layer wind environment around the building and compared with experimental results. The numerically simulated data are compared with some previous wind tunnel test data on the '+' plan building. Based on the numerical study, flow pattern near the corner regions, pressure contour, the variation of pressure coefficient along the periphery of the building, force and moment coefficients for three corner modified models are analyzed and compared with sharp edged cross plan shaped model to comprehend the extent of nonconformities due to corner modifications. The rounded corner modification is most effective in suppressing the wind load compared to chamfered and recessed corners. For rounded corners with 50% corner cut, the reduction in force and moment coefficients is substantial, with up to 26.26% and 28.58%, respectively, compared to sharp edged corners. A sudden shoot up in the negative Cp values near edges of the corner modified model, should require special attention in the design of cladding components. This paper led to comprehend the wind-induced responses of cross plan shaped building with various corner configurations.
{"title":"Aerodynamic modifications for reduction of wind loads oncross plan shaped tall building","authors":"Debasish Kumar, S. Dalui","doi":"10.12989/WAS.2021.33.2.123","DOIUrl":"https://doi.org/10.12989/WAS.2021.33.2.123","url":null,"abstract":"Corner modification plays an essential role in the reduction of the wind load and responses on tall buildings. The present study investigates the effectiveness of different corner modifications (chamfered, rounded, and recessed corners) to reduce the wind load on regular cross plan shaped tall buildings using the computation fluid dynamics technique. Here, ANSYS CFX is used to simulate the boundary layer wind environment around the building and compared with experimental results. The numerically simulated data are compared with some previous wind tunnel test data on the '+' plan building. Based on the numerical study, flow pattern near the corner regions, pressure contour, the variation of pressure coefficient along the periphery of the building, force and moment coefficients for three corner modified models are analyzed and compared with sharp edged cross plan shaped model to comprehend the extent of nonconformities due to corner modifications. The rounded corner modification is most effective in suppressing the wind load compared to chamfered and recessed corners. For rounded corners with 50% corner cut, the reduction in force and moment coefficients is substantial, with up to 26.26% and 28.58%, respectively, compared to sharp edged corners. A sudden shoot up in the negative Cp values near edges of the corner modified model, should require special attention in the design of cladding components. This paper led to comprehend the wind-induced responses of cross plan shaped building with various corner configurations.","PeriodicalId":51210,"journal":{"name":"Wind and Structures","volume":null,"pages":null},"PeriodicalIF":1.6,"publicationDate":"2021-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44395753","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-08-01DOI: 10.12989/WAS.2021.33.2.155
Meng Zhang, Jian Zhou, Guifeng Zhao, Jiankun Xu, Chao Sun
High-voltage transmission lines are featured by electrical and structural properties. Current studies on aeolian vibration of transmission lines focus primarily on structural responses of unenergized conductors. However, moderate aeolian vibration can also enhance the convection heat transfer capability of a transmission line, which improves the steady current-carrying capacity. In this paper, a fluid-structure interaction (FSI) model is established to study the structural thermal characteristics of overhead electrified aluminum conductor steel-reinforced cable (ACSR) conductors. Moreover, the fatigue damage of the energized conductor is analyzed under operational conditions. Results show that there is considerable influence from aeolian vibration on the current-carrying capacity of energized conductors. Compared with the nonelectrical conductors, aeolian vibration can enhance the convective heat transfer effect of energized conductors. Additionally, fatigue life of electrified transmission lines is larger than that of nonelectrical conductors under aeolian vibration. The developed structure-fluid-thermal model can be used to aid design and operation optimization of transmission lines.
{"title":"Study of structural-thermal characteristics of electrified conductors under aeolian vibration","authors":"Meng Zhang, Jian Zhou, Guifeng Zhao, Jiankun Xu, Chao Sun","doi":"10.12989/WAS.2021.33.2.155","DOIUrl":"https://doi.org/10.12989/WAS.2021.33.2.155","url":null,"abstract":"High-voltage transmission lines are featured by electrical and structural properties. Current studies on aeolian vibration of transmission lines focus primarily on structural responses of unenergized conductors. However, moderate aeolian vibration can also enhance the convection heat transfer capability of a transmission line, which improves the steady current-carrying capacity. In this paper, a fluid-structure interaction (FSI) model is established to study the structural thermal characteristics of overhead electrified aluminum conductor steel-reinforced cable (ACSR) conductors. Moreover, the fatigue damage of the energized conductor is analyzed under operational conditions. Results show that there is considerable influence from aeolian vibration on the current-carrying capacity of energized conductors. Compared with the nonelectrical conductors, aeolian vibration can enhance the convective heat transfer effect of energized conductors. Additionally, fatigue life of electrified transmission lines is larger than that of nonelectrical conductors under aeolian vibration. The developed structure-fluid-thermal model can be used to aid design and operation optimization of transmission lines.","PeriodicalId":51210,"journal":{"name":"Wind and Structures","volume":null,"pages":null},"PeriodicalIF":1.6,"publicationDate":"2021-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41878503","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-08-01DOI: 10.12989/WAS.2021.33.2.115
W. Cui, Lin Zhao, S. Cao, Y. Ge
In this study, an iteration-based method to simulate two typical examples of unconventional wind flow in a multi-fan wind tunnel is described: skewed non-Gaussian turbulence and sinusoidal type transient gust. The air flows are generated by 120 actively controlled fans arranged in a 10 wide by 12 high matrix. Time-varying voltages signals can be imported into the fans' servomotors, then corresponding wind flow can be produced in this wind tunnel. At first, the target wind speeds time series are converted to voltages signals, which are input into the fans' motor next, and then the initial wind flow generated can be measured. Then the wind speeds time series to be input are adjusted according to the differences between the target winds speeds and measured flow speeds. The above procedure is iteratively repeated until the measured wind flow is gradually close to the targets. At last, both non-Gaussian turbulence and transient gust can be simulated with satisfied precision after several iterations.
{"title":"Generating unconventional wind flow in an activelycontrolled multi-fan wind tunnel","authors":"W. Cui, Lin Zhao, S. Cao, Y. Ge","doi":"10.12989/WAS.2021.33.2.115","DOIUrl":"https://doi.org/10.12989/WAS.2021.33.2.115","url":null,"abstract":"In this study, an iteration-based method to simulate two typical examples of unconventional wind flow in a multi-fan wind tunnel is described: skewed non-Gaussian turbulence and sinusoidal type transient gust. The air flows are generated by 120 actively controlled fans arranged in a 10 wide by 12 high matrix. Time-varying voltages signals can be imported into the fans' servomotors, then corresponding wind flow can be produced in this wind tunnel. At first, the target wind speeds time series are converted to voltages signals, which are input into the fans' motor next, and then the initial wind flow generated can be measured. Then the wind speeds time series to be input are adjusted according to the differences between the target winds speeds and measured flow speeds. The above procedure is iteratively repeated until the measured wind flow is gradually close to the targets. At last, both non-Gaussian turbulence and transient gust can be simulated with satisfied precision after several iterations.","PeriodicalId":51210,"journal":{"name":"Wind and Structures","volume":null,"pages":null},"PeriodicalIF":1.6,"publicationDate":"2021-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45566460","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-08-01DOI: 10.12989/WAS.2021.33.2.169
M. Sajeer, A. Chakraborty
The enhancement of fatigue life of ultra-large horizontal axis wind turbine blade using longitudinal stiffening is the theme of this work. For this purpose, a tendon made of shape memory alloy is used along the longitudinal axis of blade, which is modelled in aeroelastic spinning finite element framework. The force developed in the tendon acts against the deformation where the material is modelled using Liang and Rogers constitutive relationship along with the principles of thermodynamics. The fatigue design follows the guidelines provided in internationally recognised codal provisions. The blade responses are simulated using aeroelastic loads obtained from blade element momentum theory. These dynamic responses are utilised to evaluate the longitudinal stress in the extreme fibre over the blade profile. Then, short-term and long-term damages are evaluated using rainflow matrix obtained from these stresses. Finally, the reliability of blade against fatigue failure is investigated. The numerical analysis presented in this study clearly demonstrates the performance of the longitudinal stiffening in combination with pitch angle on the fatigue life of the blade.
{"title":"Long-term fatigue reliability enhancement of horizontal axis wind turbine blade","authors":"M. Sajeer, A. Chakraborty","doi":"10.12989/WAS.2021.33.2.169","DOIUrl":"https://doi.org/10.12989/WAS.2021.33.2.169","url":null,"abstract":"The enhancement of fatigue life of ultra-large horizontal axis wind turbine blade using longitudinal stiffening is the theme of this work. For this purpose, a tendon made of shape memory alloy is used along the longitudinal axis of blade, which is modelled in aeroelastic spinning finite element framework. The force developed in the tendon acts against the deformation where the material is modelled using Liang and Rogers constitutive relationship along with the principles of thermodynamics. The fatigue design follows the guidelines provided in internationally recognised codal provisions. The blade responses are simulated using aeroelastic loads obtained from blade element momentum theory. These dynamic responses are utilised to evaluate the longitudinal stress in the extreme fibre over the blade profile. Then, short-term and long-term damages are evaluated using rainflow matrix obtained from these stresses. Finally, the reliability of blade against fatigue failure is investigated. The numerical analysis presented in this study clearly demonstrates the performance of the longitudinal stiffening in combination with pitch angle on the fatigue life of the blade.","PeriodicalId":51210,"journal":{"name":"Wind and Structures","volume":null,"pages":null},"PeriodicalIF":1.6,"publicationDate":"2021-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46273227","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-07-01DOI: 10.12989/WAS.2021.33.1.087
Y. C. Kim, Y. Tamura
Wind turbines are commonly used power generation systems around the world and their application is becoming increasingly widespread. Traditionally, they have been mounted on circular towers, but their recent upsizing has exposed weaknesses of these structures, including problems related to manufacturing and insufficient strength. Thus, the concept of site-assembled modular towers with polygonal cross-sections has been proposed, but their aerodynamic performances have not been properly investigated. In the present study, the aerodynamic performances of a wind turbine with seven polygonal towers were investigated. Wind tunnel tests have shown that the forces on the upper structure (rotor and nacelle) are larger than those on the tower, which makes the effect of cross-sectional shape of tower relatively small. Drag forces decrease with increasing number of sides of the tower, and lift forces on the square helical tower are quite small. For the power spectra, there are peaks in high reduced frequency for oblique wind directions at azimuth angles of 60° and 90°, which were considered to result from vortices that were formed and shed behind the blade in front of the tower.
{"title":"Investigation of aerodynamic performance ofpitch-control wind turbine with polygonal towers","authors":"Y. C. Kim, Y. Tamura","doi":"10.12989/WAS.2021.33.1.087","DOIUrl":"https://doi.org/10.12989/WAS.2021.33.1.087","url":null,"abstract":"Wind turbines are commonly used power generation systems around the world and their application is becoming increasingly widespread. Traditionally, they have been mounted on circular towers, but their recent upsizing has exposed weaknesses of these structures, including problems related to manufacturing and insufficient strength. Thus, the concept of site-assembled modular towers with polygonal cross-sections has been proposed, but their aerodynamic performances have not been properly investigated. In the present study, the aerodynamic performances of a wind turbine with seven polygonal towers were investigated. Wind tunnel tests have shown that the forces on the upper structure (rotor and nacelle) are larger than those on the tower, which makes the effect of cross-sectional shape of tower relatively small. Drag forces decrease with increasing number of sides of the tower, and lift forces on the square helical tower are quite small. For the power spectra, there are peaks in high reduced frequency for oblique wind directions at azimuth angles of 60° and 90°, which were considered to result from vortices that were formed and shed behind the blade in front of the tower.","PeriodicalId":51210,"journal":{"name":"Wind and Structures","volume":null,"pages":null},"PeriodicalIF":1.6,"publicationDate":"2021-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46009179","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-07-01DOI: 10.12989/WAS.2021.33.1.041
Jiajun He, Huo-yue Xiang, Wenyuan Ren, Yongle Li
Constructing combined highway–railway bridge brings concerns regarding the aerodynamic interference between train and road vehicle. Research on the interaction mechanism can help calculate the vehicle response for the assessment of travelling safety. In this work, computational fluid dynamics (CFD) verified by a moving model test was applied on researching the aerodynamic characteristics of a moving van under the influence of train-induced wind. Two processes - encounter process (train and van drive towards each other) and chase process (train surpasses the van), are compared. The aerodynamic forces and pressure distribution of the van as well as the flow fields around the vehicles during the interaction are analyzed coherently. The results reveal that the adjacent positive and negative pressure zones around the nose and tail of the train bring moving and centralized high-pressure zone on the van's flank and generate significant aerodynamic variations, each variation contains at least two peak/valley values, and the middle carriage provide a stable transition between. Different superposition effect of the pressure zones results in difference between the encounter process and chase process, the variation trend of drag force and lift in the two processes are similar while the encounter has larger variation amplitude, in terms of pitching moment and yawing moment, more inversions of force happen in the encounter process but the variation amplitude is smaller. When the van runs near the nose of the train in the encounter, it gets the largest variation of drag force, lift force and rolling moment, while the largest variation of yawing moment and pitching moment happens when it runs near the nose of the train in the chase process.
{"title":"Numerical simulation on aerodynamic characteristics of moving van under the train-induced wind","authors":"Jiajun He, Huo-yue Xiang, Wenyuan Ren, Yongle Li","doi":"10.12989/WAS.2021.33.1.041","DOIUrl":"https://doi.org/10.12989/WAS.2021.33.1.041","url":null,"abstract":"Constructing combined highway–railway bridge brings concerns regarding the aerodynamic interference between train and road vehicle. Research on the interaction mechanism can help calculate the vehicle response for the assessment of travelling safety. In this work, computational fluid dynamics (CFD) verified by a moving model test was applied on researching the aerodynamic characteristics of a moving van under the influence of train-induced wind. Two processes - encounter process (train and van drive towards each other) and chase process (train surpasses the van), are compared. The aerodynamic forces and pressure distribution of the van as well as the flow fields around the vehicles during the interaction are analyzed coherently. The results reveal that the adjacent positive and negative pressure zones around the nose and tail of the train bring moving and centralized high-pressure zone on the van's flank and generate significant aerodynamic variations, each variation contains at least two peak/valley values, and the middle carriage provide a stable transition between. Different superposition effect of the pressure zones results in difference between the encounter process and chase process, the variation trend of drag force and lift in the two processes are similar while the encounter has larger variation amplitude, in terms of pitching moment and yawing moment, more inversions of force happen in the encounter process but the variation amplitude is smaller. When the van runs near the nose of the train in the encounter, it gets the largest variation of drag force, lift force and rolling moment, while the largest variation of yawing moment and pitching moment happens when it runs near the nose of the train in the chase process.","PeriodicalId":51210,"journal":{"name":"Wind and Structures","volume":null,"pages":null},"PeriodicalIF":1.6,"publicationDate":"2021-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43462030","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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