Pub Date : 2021-07-01DOI: 10.12989/WAS.2021.33.1.001
Z. Yao, Nan Zhang
The overturning issues in a strong wind are extremely critical to the railway vehicles, which have attracted a great deal of attention over the years. To address such problems, this paper introduces a dynamic reliability approach to evaluate the overturning risk of vehicles in crosswinds. Starting from the aerodynamic model, a novel prediction formula of unsteady crosswind forces with a consideration of the complete turbulent field effect is derived. Using the pseudo-excitation method (PEM), the power spectrum of vehicle responses is then calculated by the established vehicle model, and finally the corresponding results are used to assess the probabilistic overturning of vehicles in terms of the dynamic reliability analysis. It is found from the calculations that the time-dependent failure probability curves are related to the vehicle speed, wind speed, and crosswind direction, and the probabilistic characteristic wind curves (PCWCs) at different failure probabilities are more useful and reasonable for evaluating the overturning risk in comparison with the traditional characteristic wind curves (CWCs) in previous investigations. Furthermore, the probabilistic characteristic wind surface (PCWS) that considers the effect of crosswind direction, is developed, and it reveals that the vehicle is most vulnerable at a condition of perpendicular crosswind direction.
{"title":"Overturning assessment of railway vehicles under cross winds","authors":"Z. Yao, Nan Zhang","doi":"10.12989/WAS.2021.33.1.001","DOIUrl":"https://doi.org/10.12989/WAS.2021.33.1.001","url":null,"abstract":"The overturning issues in a strong wind are extremely critical to the railway vehicles, which have attracted a great deal of attention over the years. To address such problems, this paper introduces a dynamic reliability approach to evaluate the overturning risk of vehicles in crosswinds. Starting from the aerodynamic model, a novel prediction formula of unsteady crosswind forces with a consideration of the complete turbulent field effect is derived. Using the pseudo-excitation method (PEM), the power spectrum of vehicle responses is then calculated by the established vehicle model, and finally the corresponding results are used to assess the probabilistic overturning of vehicles in terms of the dynamic reliability analysis. It is found from the calculations that the time-dependent failure probability curves are related to the vehicle speed, wind speed, and crosswind direction, and the probabilistic characteristic wind curves (PCWCs) at different failure probabilities are more useful and reasonable for evaluating the overturning risk in comparison with the traditional characteristic wind curves (CWCs) in previous investigations. Furthermore, the probabilistic characteristic wind surface (PCWS) that considers the effect of crosswind direction, is developed, and it reveals that the vehicle is most vulnerable at a condition of perpendicular crosswind direction.","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":"46578226","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.2021.33.1.029
D. Lee, Dasaraden Mauree
The current paper presents an investigation, which has its main objective in the verification of outdoor wind flow CFD simulation results (ANSYS R Fluent) with real environment measurements in urban setting. The details of the simulation set-up are discussed in the paper including the inlet boundary conditions, surface roughness parameters and the source/sink terms to represent the effect of trees. The simulation results are compared with the high-resolution on-site wind velocity measurements from the Measurement of Turbulence in an Urban Setup (MoTUS) project of Ecole Polytechnique Federale de Lausanne (EPFL) in Switzerland. Multiple simulations were conducted to evaluate the performance of the model based on different wind direction and speeds. At the end of the current study, the highly consistent and accurate results were observed from all 18 verification cases; with the RMSEs of the simulated wind velocities in range of 0.21 and 0.59 m/s only.
本文提出了一项研究，其主要目的是通过城市环境中的真实环境测量来验证室外气流CFD模拟结果（ANSYS R Fluent）。本文讨论了模拟设置的细节，包括入口边界条件、表面粗糙度参数和表示树木影响的源/汇项。将模拟结果与瑞士洛桑联邦理工学院（EPFL）城市设置湍流测量项目（MoTUS）的高分辨率现场风速测量结果进行了比较。基于不同的风向和风速，进行了多次模拟以评估模型的性能。在本研究结束时，从所有18个验证案例中观察到高度一致和准确的结果；模拟风速的均方根误差仅在0.21和0.59m/s之间。
{"title":"RANS based CFD Simulations for Urban Wind Prediction –Field Verification against MoTUS","authors":"D. Lee, Dasaraden Mauree","doi":"10.12989/WAS.2021.33.1.029","DOIUrl":"https://doi.org/10.12989/WAS.2021.33.1.029","url":null,"abstract":"The current paper presents an investigation, which has its main objective in the verification of outdoor wind flow CFD simulation results (ANSYS R Fluent) with real environment measurements in urban setting. The details of the simulation set-up are discussed in the paper including the inlet boundary conditions, surface roughness parameters and the source/sink terms to represent the effect of trees. The simulation results are compared with the high-resolution on-site wind velocity measurements from the Measurement of Turbulence in an Urban Setup (MoTUS) project of Ecole Polytechnique Federale de Lausanne (EPFL) in Switzerland. Multiple simulations were conducted to evaluate the performance of the model based on different wind direction and speeds. At the end of the current study, the highly consistent and accurate results were observed from all 18 verification cases; with the RMSEs of the simulated wind velocities in range of 0.21 and 0.59 m/s only.","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":"49103145","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.2021.33.1.013
Mengen Wang, S. Cao, Jinxin Cao
In this study, three representative configurations of tornado-like vortices, i.e., single vortex, vortex breakdown and multi-vortex, are numerically simulated using large-eddy simulation (LES). Proper orthogonal decomposition (POD) is firstly employed to decompose flow-field snapshots into a series of orthogonal flow patterns (POD modes) and time-dependent coefficients. Then, a conditional-average analysis is conducted to obtain the four kinds of conditionally-averaged flow fields, which are then compared with instantaneous and ensemble-averaged flow fields. Next, a quadruple POD analysis is performed to decompose the instantaneous flow field into mean, coherent, transition and noise components. Finally, a qualitative analysis is implemented for unsteady vortex motions in horizontal and vertical planes. Results show that the conditional average shows larger-scale coherent structures than the classical ensemble average, while it loses the small-scale turbulent fluctuations present in instantaneous flow. The tornado vortex structure is controlled by the mean component in the single-vortex stage. With increase in swirl ratio, the tornado vortex evolves from single-vortex, to vortex-breakdown to multi-vortex, companied by kinetic energy transference to coherent and transition components. The horizontal and vertical vortex motions are essentially the results of horizontal and vertical velocity perturbations.
{"title":"POD-based analysis of time-resolved tornado-like vortices","authors":"Mengen Wang, S. Cao, Jinxin Cao","doi":"10.12989/WAS.2021.33.1.013","DOIUrl":"https://doi.org/10.12989/WAS.2021.33.1.013","url":null,"abstract":"In this study, three representative configurations of tornado-like vortices, i.e., single vortex, vortex breakdown and multi-vortex, are numerically simulated using large-eddy simulation (LES). Proper orthogonal decomposition (POD) is firstly employed to decompose flow-field snapshots into a series of orthogonal flow patterns (POD modes) and time-dependent coefficients. Then, a conditional-average analysis is conducted to obtain the four kinds of conditionally-averaged flow fields, which are then compared with instantaneous and ensemble-averaged flow fields. Next, a quadruple POD analysis is performed to decompose the instantaneous flow field into mean, coherent, transition and noise components. Finally, a qualitative analysis is implemented for unsteady vortex motions in horizontal and vertical planes. Results show that the conditional average shows larger-scale coherent structures than the classical ensemble average, while it loses the small-scale turbulent fluctuations present in instantaneous flow. The tornado vortex structure is controlled by the mean component in the single-vortex stage. With increase in swirl ratio, the tornado vortex evolves from single-vortex, to vortex-breakdown to multi-vortex, companied by kinetic energy transference to coherent and transition components. The horizontal and vertical vortex motions are essentially the results of horizontal and vertical velocity perturbations.","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":"48195168","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.2021.33.1.103
Chenzhi Ma, Zheng Lu, Dianchao Wang, Zixin Wang
Intensive attention has been given to mitigating the dynamic responses of wind turbine towers (WTs) under wind and seismic excitations to ensure their safety and serviceability. This study details the damping mechanisms of a suspended particle damper (suspended PD) on the vibration control of a horizontal-axis WT. This damper combines the benefits of a tuned mass damper (TMD) and fixed PD, and can be effective without an external damping system. It therefore is a more practical solution for the vibration control of a WT. In this study, a finite element WT is built, and two damper systems with a TMD and suspended PD are modeled and compared. Ground motions and strong lateral winds are applied as external excitations to the operational and parked turbines, respectively. A full factorial study using a statistical method is conducted to determine the interaction effects of key parameters of the suspended PD. Results show that the damping effectiveness of a suspended PD is not sensitive to the external damping system under specific parameters, and it can be effective in detuned cases. Finally, a comparison between the optimal TMD and suspended PD on the vibration control of a WT is performed. The comparative results indicate that the performance of the suspended PD is considerably more robust than the TMD in wind-seismic excitations.
{"title":"Study on the damping mechanisms of a suspended particle damperattached to a wind turbine tower","authors":"Chenzhi Ma, Zheng Lu, Dianchao Wang, Zixin Wang","doi":"10.12989/WAS.2021.33.1.103","DOIUrl":"https://doi.org/10.12989/WAS.2021.33.1.103","url":null,"abstract":"Intensive attention has been given to mitigating the dynamic responses of wind turbine towers (WTs) under wind and seismic excitations to ensure their safety and serviceability. This study details the damping mechanisms of a suspended particle damper (suspended PD) on the vibration control of a horizontal-axis WT. This damper combines the benefits of a tuned mass damper (TMD) and fixed PD, and can be effective without an external damping system. It therefore is a more practical solution for the vibration control of a WT. In this study, a finite element WT is built, and two damper systems with a TMD and suspended PD are modeled and compared. Ground motions and strong lateral winds are applied as external excitations to the operational and parked turbines, respectively. A full factorial study using a statistical method is conducted to determine the interaction effects of key parameters of the suspended PD. Results show that the damping effectiveness of a suspended PD is not sensitive to the external damping system under specific parameters, and it can be effective in detuned cases. Finally, a comparison between the optimal TMD and suspended PD on the vibration control of a WT is performed. The comparative results indicate that the performance of the suspended PD is considerably more robust than the TMD in wind-seismic excitations.","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":"46983019","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.2021.33.1.071
Lin Zhao, Shengyuan Liu, Junfeng Yan, Y. Ge
In classical buffeting analysis theory, aerodynamic forces are usually expressed by a linear quasi-steady formula, and they are improved by aerodynamic admittances suitable for streamlined bridge girders. Recent studies have shown that admittances change obviously with incoming flow characteristics and aerodynamic nonlinearity, such as the frequency multiplication phenomenon, and motion-induced amplitude-related aerodynamic effects cannot be ignored in some cases. To address these problems, a nonlinear condensed subsystem equation (NCSE) suitable for wind-induced aerodynamic force modeling is established in the time domain. It characterizes aerodynamic nonlinearity with series of nonlinear differential equations and data-driven parameters. The proposed framework can be used for complex aerodynamic re-illustration related to the strong nonlinearity of streamlined box girders. To validate the precision and feasibility of the framework, sectional model experiments performed on a streamlined box girder were carried out in an active turbulence generated wind tunnel in which an adjustable array of multiple fans was assisted by actively controlled vibrating wings for a 2D turbulence condition. The case study shows that the NCSE model can be used to predict nonlinear aerodynamic forces in the time and frequency domains, even under complex stochastic flow conditions. The proposed method provides an alternative way to predict possible aerodynamics based on the condition of incoming flow with sufficient accuracy, and it can illustrate multifrequency components of aerodynamic forces.
{"title":"Aerodynamic modeling for streamlined box girders using nonlinear differential equations and validation in actively generated turbulence","authors":"Lin Zhao, Shengyuan Liu, Junfeng Yan, Y. Ge","doi":"10.12989/WAS.2021.33.1.071","DOIUrl":"https://doi.org/10.12989/WAS.2021.33.1.071","url":null,"abstract":"In classical buffeting analysis theory, aerodynamic forces are usually expressed by a linear quasi-steady formula, and they are improved by aerodynamic admittances suitable for streamlined bridge girders. Recent studies have shown that admittances change obviously with incoming flow characteristics and aerodynamic nonlinearity, such as the frequency multiplication phenomenon, and motion-induced amplitude-related aerodynamic effects cannot be ignored in some cases. To address these problems, a nonlinear condensed subsystem equation (NCSE) suitable for wind-induced aerodynamic force modeling is established in the time domain. It characterizes aerodynamic nonlinearity with series of nonlinear differential equations and data-driven parameters. The proposed framework can be used for complex aerodynamic re-illustration related to the strong nonlinearity of streamlined box girders. To validate the precision and feasibility of the framework, sectional model experiments performed on a streamlined box girder were carried out in an active turbulence generated wind tunnel in which an adjustable array of multiple fans was assisted by actively controlled vibrating wings for a 2D turbulence condition. The case study shows that the NCSE model can be used to predict nonlinear aerodynamic forces in the time and frequency domains, even under complex stochastic flow conditions. The proposed method provides an alternative way to predict possible aerodynamics based on the condition of incoming flow with sufficient accuracy, and it can illustrate multifrequency components of aerodynamic forces.","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":"48976745","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 : 2021-06-01DOI: 10.12989/WAS.2021.32.6.539
M. Mohebbi, M. Rezvani
This perusal surveys the design criteria indispensable for fences that are installed alongside the high-speed railway tracks to protect the passing high-speed rolling stock under strong side winds. Using a numerical code based on Lattice Boltzmann Method (LBM) it is attempted to initially investigate the airflow behavior behind the fences. A variety of geometries for air fences in a two-dimensional space are compared. A wind tunnel test is performed to verify the numerical results. The three-dimensional flow patterns around the German Intercity Express (ICE3) high-speed train with and without the air fences are numerically examined to be more realistic. It is found that the presence of the fences has a significant impact on decreasing the intensity of the airflow above the train. The edges on the top of the fences cause more reduction in the velocity of air flowing above the train.
{"title":"2D and 3D numerical and experimental analyses ofthe aerodynamic effects of air fences on a high-speed train","authors":"M. Mohebbi, M. Rezvani","doi":"10.12989/WAS.2021.32.6.539","DOIUrl":"https://doi.org/10.12989/WAS.2021.32.6.539","url":null,"abstract":"This perusal surveys the design criteria indispensable for fences that are installed alongside the high-speed railway \u0000tracks to protect the passing high-speed rolling stock under strong side winds. Using a numerical code based on Lattice Boltzmann Method (LBM) it is attempted to initially investigate the airflow behavior behind the fences. A variety of geometries for air fences in a two-dimensional space are compared. A wind tunnel test is performed to verify the numerical results. The three-dimensional flow patterns around the German Intercity Express (ICE3) high-speed train with and without the air fences are \u0000numerically examined to be more realistic. It is found that the presence of the fences has a significant impact on decreasing the intensity of the airflow above the train. The edges on the top of the fences cause more reduction in the velocity of air flowing above the train.","PeriodicalId":51210,"journal":{"name":"Wind and Structures","volume":null,"pages":null},"PeriodicalIF":1.6,"publicationDate":"2021-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49131450","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 : 2021-06-01DOI: 10.12989/WAS.2021.32.6.597
Lei Zhou, Tang-hong Liu, Zhengwei Chen, Wen-hui Li, Zi-jian Guo, Xuhui He, Youwu Wang
This paper studied the case of high-speed train running from flat ground to bridges and into/out of tunnels, with or without crosswind based on the Computational Fluid Dynamics (CFD) method. First, the flow structure was analyzed to explain the influence mechanisms of different infrastructures on the aerodynamic characteristics of the train. Then, the evolution of aerodynamic forces of the train during the entire process was analyzed and compared. Additionally, the pressure variation on the train body and the tunnel wall was examined in detail. The results showed that the pressure coefficient and the flow structure on both sides of the high-speed train were symmetrical for no crosswind case. By contrast, under crosswind, there was a tremendous and immediate change in the pressure mapping and flow structure when the train passing through the bridge-tunnel section. The influence of the ground-bridge transition on the aerodynamic forces was much smaller than that of the bridge-tunnel section. Moreover, the variation of aerodynamic load during the process of entering and exiting the bridge-tunnel sections was both significant. In addition, in the case without crosswind, the change in the pressure change in the tunnel conformed to the law of pressure wave propagation, while under crosswind, the variation in pressure was comprehensively affected by both the train and crosswind in the tunnel.
{"title":"Comparison study of the effect of bridge-tunnel transition on train aerodynamic performance with or without crosswind","authors":"Lei Zhou, Tang-hong Liu, Zhengwei Chen, Wen-hui Li, Zi-jian Guo, Xuhui He, Youwu Wang","doi":"10.12989/WAS.2021.32.6.597","DOIUrl":"https://doi.org/10.12989/WAS.2021.32.6.597","url":null,"abstract":"This paper studied the case of high-speed train running from flat ground to bridges and into/out of tunnels, with or \u0000without crosswind based on the Computational Fluid Dynamics (CFD) method. First, the flow structure was analyzed to explain \u0000the influence mechanisms of different infrastructures on the aerodynamic characteristics of the train. Then, the evolution of \u0000aerodynamic forces of the train during the entire process was analyzed and compared. Additionally, the pressure variation on the \u0000train body and the tunnel wall was examined in detail. The results showed that the pressure coefficient and the flow structure on \u0000both sides of the high-speed train were symmetrical for no crosswind case. By contrast, under crosswind, there was a \u0000tremendous and immediate change in the pressure mapping and flow structure when the train passing through the bridge-tunnel section. The influence of the ground-bridge transition on the aerodynamic forces was much smaller than that of the bridge-tunnel section. Moreover, the variation of aerodynamic load during the process of entering and exiting the bridge-tunnel sections was both significant. In addition, in the case without crosswind, the change in the pressure change in the tunnel conformed to the law of pressure wave propagation, while under crosswind, the variation in pressure was comprehensively affected by both the train and crosswind in the tunnel.","PeriodicalId":51210,"journal":{"name":"Wind and Structures","volume":null,"pages":null},"PeriodicalIF":1.6,"publicationDate":"2021-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48325210","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 : 2021-06-01DOI: 10.12989/WAS.2021.32.6.613
Serdar Şahin, T. Durhasan, Engin Pinar, H. Akilli
Present experimental investigation aims to reduce the shedding of vortex in the near wake region of a circular cylinder using a perforated splitter plate. Perforated plates were placed in the wake region of the cylinder and aligned with the streamwise direction. The length of the plates was equal to the diameter of the cylinder. Different plate porosities and locations were examined and obtained results were compared to the baseline cylinder. Flow measurements downstream of the cylinder were performed in a water channel by employing a particle image velocimetry technique (PIV) at a Reynolds number of Re=5x103. It is observed that the effect of the porosity on the flow characteristics of the cylinder depends on the location of the plate. The strength of shear layers and flow fluctuations in the near wake region of the cylinder are considerably diminished by the perforated splitter plate. It is found that the porosity of e=0.3 is the most effective control element for gap ratio of G/D=0.5. On the other hand, proper gap ratio is determined as G/D=2 for porosity of e=0.7. It is concluded in the present study that the perforated splitter plate could be used as alternative passive flow control technique in order to reduce vortex shedding of the cylinder.
{"title":"Experimental study on passive flow control of circular cylinder via perforated splitter plate","authors":"Serdar Şahin, T. Durhasan, Engin Pinar, H. Akilli","doi":"10.12989/WAS.2021.32.6.613","DOIUrl":"https://doi.org/10.12989/WAS.2021.32.6.613","url":null,"abstract":"Present experimental investigation aims to reduce the shedding of vortex in the near wake region of a circular \u0000cylinder using a perforated splitter plate. Perforated plates were placed in the wake region of the cylinder and aligned with the streamwise direction. The length of the plates was equal to the diameter of the cylinder. Different plate porosities and locations were examined and obtained results were compared to the baseline cylinder. Flow measurements downstream of the cylinder were performed in a water channel by employing a particle image velocimetry technique (PIV) at a Reynolds number of Re=5x103. It is observed that the effect of the porosity on the flow characteristics of the cylinder depends on the location of the plate. The strength of shear layers and flow fluctuations in the near wake region of the cylinder are considerably diminished by the perforated splitter plate. It is found that the porosity of e=0.3 is the most effective control element for gap ratio of G/D=0.5. \u0000On the other hand, proper gap ratio is determined as G/D=2 for porosity of e=0.7. It is concluded in the present study that the perforated splitter plate could be used as alternative passive flow control technique in order to reduce vortex shedding of the cylinder.","PeriodicalId":51210,"journal":{"name":"Wind and Structures","volume":null,"pages":null},"PeriodicalIF":1.6,"publicationDate":"2021-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43102498","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 : 2021-06-01DOI: 10.12989/WAS.2021.32.6.573
Ruifu Zhang, Yanru Cao, K. Dai
Wind turbine towers are sensitive to wind loads and lose efficiency when suffering excessive wind-induced vibrations. Structural control techniques such as tuned mass dampers (TMD) can be used to reduce the vibration response of the tower. However, the additional mass of this system would occupy a large amount of space within the wind turbine device, which can inconvenience installation and maintenance. An inerter is a high-efficiency two terminal mechanical element for vibration control with the characteristic of mass and damping enhancements. An ungrounded tuned mass inerter system (TMIS) –composed of a tuned mass, a tuned spring and an inerter subsystem – has potential to control wind-induced vibration efficiently. In this study, a simple design method for wind turbine towers equipped with a TMIS under wind loads is proposed, based on structural performance demand as well as control cost. A 1.5 MW wind turbine tower benchmark model is adopted to exemplify the proposed design method. Comparative analyses are conducted between a conventional TMD and the TMIS. Results show that the TMIS can achieve the same vibration control effect as the TMD while using a smaller tuned mass. A sensitivity study of the TMIS is also carried out to investigate the impact of mechanical element parameters on the performance of the vibration mitigation system. It is concluded that the optimal designed TMIS has the advantage of lightweight tuned mass over TMDs in wind-induce vibration control of wind turbine towers.
{"title":"Response control of wind turbines with ungrounded tuned mass inerter system (TMIS) under wind loads","authors":"Ruifu Zhang, Yanru Cao, K. Dai","doi":"10.12989/WAS.2021.32.6.573","DOIUrl":"https://doi.org/10.12989/WAS.2021.32.6.573","url":null,"abstract":"Wind turbine towers are sensitive to wind loads and lose efficiency when suffering excessive wind-induced \u0000vibrations. Structural control techniques such as tuned mass dampers (TMD) can be used to reduce the vibration response of the tower. However, the additional mass of this system would occupy a large amount of space within the wind turbine device, which can inconvenience installation and maintenance. An inerter is a high-efficiency two terminal mechanical element for vibration control with the characteristic of mass and damping enhancements. An ungrounded tuned mass inerter system (TMIS) –composed of a tuned mass, a tuned spring and an inerter subsystem – has potential to control wind-induced vibration efficiently. \u0000In this study, a simple design method for wind turbine towers equipped with a TMIS under wind loads is proposed, based on structural performance demand as well as control cost. A 1.5 MW wind turbine tower benchmark model is adopted to exemplify the proposed design method. Comparative analyses are conducted between a conventional TMD and the TMIS. Results show that the TMIS can achieve the same vibration control effect as the TMD while using a smaller tuned mass. A sensitivity study of the TMIS is also carried out to investigate the impact of mechanical element parameters on the performance of the vibration mitigation system. It is concluded that the optimal designed TMIS has the advantage of lightweight tuned mass over TMDs in wind-induce vibration control of wind turbine towers.","PeriodicalId":51210,"journal":{"name":"Wind and Structures","volume":null,"pages":null},"PeriodicalIF":1.6,"publicationDate":"2021-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45793692","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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