Pub Date : 2024-11-16DOI: 10.1016/j.jweia.2024.105956
Feng Liu , Mengjie Wei , Haibo Yang , Wenzhe Yang , Dawei Chen
The entry of a high-speed train into a tunnel triggers severe micro pressure wave (MPW), posing a major obstacle to the fast and environmentally friendly operation of trains. The installation of a retaining block structure in the tunnel can alter the propagation process of the compression waves, thereby mitigating the effects of MPWs. In this research, a two-dimensional-axisymmetric retaining block is taken as the research object. Based on CFD and an experimental device for generating initial wavefronts, we investigate the influence of the retaining block's radial, axial lengths and the installation location, on the mitigation of wavefront steepening. It is found that the results of numerical simulations compare favourably with those of the experimental device. In mitigating the steepening of the wavefront, there is a critical value for retaining block's axial length which is about 1/4 of the length of S-shaped initial wavefront, and the retaining block is more effective when the wavefront pressure gradient is higher. This implies that when considering the inertial effect of the wavefront inside medium to long tunnels, the retaining block should be placed as close as possible to the tunnel exit to minimize the maximum pressure gradient of the wavefront. The results of this paper may provide a new approach for improving the evolution of pressure waves in tunnels.
高速列车进入隧道时会引发严重的微压力波（MPW），对列车的快速和环保运行构成重大障碍。在隧道中安装挡块结构可以改变压缩波的传播过程，从而减轻 MPW 的影响。本研究以二维轴对称挡块为研究对象。基于 CFD 和产生初始波面的实验装置，我们研究了挡块的径向、轴向长度和安装位置对缓解波面陡化的影响。结果发现，数值模拟的结果与实验装置的结果相差无几。在缓解波前陡化方面，挡块的轴向长度存在一个临界值，约为 S 型初始波前长度的 1/4，当波前压力梯度较大时，挡块的作用效果更好。这意味着在考虑中长隧道内波面的惯性效应时，挡块应尽可能靠近隧道出口，以减小波面的最大压力梯度。本文的研究结果可为改善隧道内压力波的演变提供一种新方法。
{"title":"Numerical simulation and experimental study of the effects of retaining block structures on wavefront steepening in rail tunnels","authors":"Feng Liu , Mengjie Wei , Haibo Yang , Wenzhe Yang , Dawei Chen","doi":"10.1016/j.jweia.2024.105956","DOIUrl":"10.1016/j.jweia.2024.105956","url":null,"abstract":"<div><div>The entry of a high-speed train into a tunnel triggers severe micro pressure wave (MPW), posing a major obstacle to the fast and environmentally friendly operation of trains. The installation of a retaining block structure in the tunnel can alter the propagation process of the compression waves, thereby mitigating the effects of MPWs. In this research, a two-dimensional-axisymmetric retaining block is taken as the research object. Based on CFD and an experimental device for generating initial wavefronts, we investigate the influence of the retaining block's radial, axial lengths and the installation location, on the mitigation of wavefront steepening. It is found that the results of numerical simulations compare favourably with those of the experimental device. In mitigating the steepening of the wavefront, there is a critical value for retaining block's axial length which is about 1/4 of the length of S-shaped initial wavefront, and the retaining block is more effective when the wavefront pressure gradient is higher. This implies that when considering the inertial effect of the wavefront inside medium to long tunnels, the retaining block should be placed as close as possible to the tunnel exit to minimize the maximum pressure gradient of the wavefront. The results of this paper may provide a new approach for improving the evolution of pressure waves in tunnels.</div></div>","PeriodicalId":54752,"journal":{"name":"Journal of Wind Engineering and Industrial Aerodynamics","volume":"255 ","pages":"Article 105956"},"PeriodicalIF":4.2,"publicationDate":"2024-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142660460","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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 : 2024-11-16DOI: 10.1016/j.jweia.2024.105948
Jue Wang, Ruoyu You
Turbulence models are crucial for simulating urban pollutant dispersion by computational fluid dynamics (CFD) methods. This study aimed to evaluate the performance of steady-state and unsteady-state Reynolds-averaged Navier-Stokes simulation (SRANS/URANS) and large-eddy simulation (LES) in calculating air pollutant dispersion in street canyons with generic and real urban layouts. For each layout, wind tunnel experiments with measured wind speed and pollutant concentration were available as benchmarks. In addition, instantaneous concentration fields were analyzed to assess the transient models. The results showed that in both generic and real urban layouts, the RNG model and SST model provided similar results for time-averaged wind speed and concentration distributions in SRANS and URANS simulations. LES performed the best in calculating wind speed and pollutant dispersion. In a generic urban layout, URANS with the SST model captured large-scale fluctuations, while instantaneous results from URANS with the SST model did not change over time in a real urban layout. SRANS/URANS with the SST model can provide acceptable results for time-averaged pollutant concentration fields in a generic urban layout with simple building shapes and placements. However, for real urban layouts, the LES approach is the most accurate way to calculate air pollutant dispersion.
{"title":"Evaluating different categories of turbulence models for calculating air pollutant dispersion in street canyons with generic and real urban layouts","authors":"Jue Wang, Ruoyu You","doi":"10.1016/j.jweia.2024.105948","DOIUrl":"10.1016/j.jweia.2024.105948","url":null,"abstract":"<div><div>Turbulence models are crucial for simulating urban pollutant dispersion by computational fluid dynamics (CFD) methods. This study aimed to evaluate the performance of steady-state and unsteady-state Reynolds-averaged Navier-Stokes simulation (SRANS/URANS) and large-eddy simulation (LES) in calculating air pollutant dispersion in street canyons with generic and real urban layouts. For each layout, wind tunnel experiments with measured wind speed and pollutant concentration were available as benchmarks. In addition, instantaneous concentration fields were analyzed to assess the transient models. The results showed that in both generic and real urban layouts, the RNG <span><math><mrow><mi>k</mi><mo>−</mo><mi>ε</mi></mrow></math></span> model and SST <span><math><mrow><mi>k</mi><mo>−</mo><mi>ω</mi></mrow></math></span> model provided similar results for time-averaged wind speed and concentration distributions in SRANS and URANS simulations. LES performed the best in calculating wind speed and pollutant dispersion. In a generic urban layout, URANS with the SST <span><math><mrow><mi>k</mi><mo>−</mo><mi>ω</mi></mrow></math></span> model captured large-scale fluctuations, while instantaneous results from URANS with the SST <span><math><mrow><mi>k</mi><mo>−</mo><mi>ω</mi></mrow></math></span> model did not change over time in a real urban layout. SRANS/URANS with the SST <span><math><mrow><mi>k</mi><mo>−</mo><mi>ω</mi></mrow></math></span> model can provide acceptable results for time-averaged pollutant concentration fields in a generic urban layout with simple building shapes and placements. However, for real urban layouts, the LES approach is the most accurate way to calculate air pollutant dispersion.</div></div>","PeriodicalId":54752,"journal":{"name":"Journal of Wind Engineering and Industrial Aerodynamics","volume":"255 ","pages":"Article 105948"},"PeriodicalIF":4.2,"publicationDate":"2024-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142660459","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
With the rapid development of wind energy, accurately predicting the wake speed distribution behind wind turbines is crucial for load assessment and coordinated control of wind farms. However, existing wake models still fall short in accurately predicting under the complex and variable inflow characteristics and turbine operating states in actual wind farms. To address this issue, this paper proposes a wake prediction framework that combines the Gaussian wake model based on Monin-Obukhov Similarity Theory (MOST) and deep learning approach. In this framework, the MOST Gaussian wake model is improved to account for yaw correction, and the one-dimensional convolutional neural network-bidirectional long-short-term memory (1DCNN-BiLSTM) deep learning model is employed to dynamically calibrate the wake expansion rate parameters using both inflow characteristics and turbine operating states as inputs. Validation with actual wind farm case studies shows the proposed framework achieves 95.35% wind speed prediction accuracy and 84.17% power accuracy at Penmanshiel wind farm, and 97.12% wind speed accuracy and 87.59% power accuracy at La Haute Born wind farm. The high prediction accuracy of this framework provides a reliable basis for future load assessment and coordinated control of wind farms and offers new ideas for optimizing wind farm design and operation strategies.
随着风能的快速发展，准确预测风力涡轮机后方的尾流速度分布对于风电场的负荷评估和协调控制至关重要。然而，现有的尾流模型仍无法准确预测实际风电场中复杂多变的流入特性和风机运行状态。为解决这一问题，本文提出了一种基于莫宁-奥布霍夫相似理论（MOST）的高斯唤醒模型与深度学习方法相结合的唤醒预测框架。在该框架中，改进了 MOST 高斯尾流模型以考虑偏航修正，并采用一维卷积神经网络-双向长短期记忆（1DCNN-BiLSTM）深度学习模型，以流入特征和风机运行状态为输入，动态校准尾流扩展率参数。实际风电场案例研究的验证表明，所提出的框架在 Penmanshiel 风电场实现了 95.35% 的风速预测精度和 84.17% 的功率预测精度，在 La Haute Born 风电场实现了 97.12% 的风速预测精度和 87.59% 的功率预测精度。该框架的高预测精度为未来风电场的负荷评估和协调控制提供了可靠依据，并为优化风电场设计和运行策略提供了新思路。
{"title":"A wake prediction framework based on the MOST Gaussian wake model and a deep learning approach","authors":"Mingwei Wang, Mingming Zhang, Lulu Zhao, Caiyan Qin","doi":"10.1016/j.jweia.2024.105952","DOIUrl":"10.1016/j.jweia.2024.105952","url":null,"abstract":"<div><div>With the rapid development of wind energy, accurately predicting the wake speed distribution behind wind turbines is crucial for load assessment and coordinated control of wind farms. However, existing wake models still fall short in accurately predicting under the complex and variable inflow characteristics and turbine operating states in actual wind farms. To address this issue, this paper proposes a wake prediction framework that combines the Gaussian wake model based on Monin-Obukhov Similarity Theory (MOST) and deep learning approach. In this framework, the MOST Gaussian wake model is improved to account for yaw correction, and the one-dimensional convolutional neural network-bidirectional long-short-term memory (1DCNN-BiLSTM) deep learning model is employed to dynamically calibrate the wake expansion rate parameters using both inflow characteristics and turbine operating states as inputs. Validation with actual wind farm case studies shows the proposed framework achieves 95.35% wind speed prediction accuracy and 84.17% power accuracy at Penmanshiel wind farm, and 97.12% wind speed accuracy and 87.59% power accuracy at La Haute Born wind farm. The high prediction accuracy of this framework provides a reliable basis for future load assessment and coordinated control of wind farms and offers new ideas for optimizing wind farm design and operation strategies.</div></div>","PeriodicalId":54752,"journal":{"name":"Journal of Wind Engineering and Industrial Aerodynamics","volume":"255 ","pages":"Article 105952"},"PeriodicalIF":4.2,"publicationDate":"2024-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142660007","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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 : 2024-11-15DOI: 10.1016/j.jweia.2024.105931
G. Bacci , Ø.W. Petersen , V. Denoël , O. Øiseth
This paper presents a detailed statistical analysis of strong hanger vortex-induced vibrations (VIV) at the Hålogaland Bridge in Narvik, Norway. Severe VIV during construction led to the installation of Stockbridge dampers post-completion. Unfortunately, many dampers broke within a year, prompting a long-term measurement campaign. The measurements highlight the complexity of observed VIV, with non-stationary and multi-frequency vibrations during constant wind speeds. The paper assesses the effectiveness of various damper configurations on the hangers and finds that a single damper notably reduces vibration amplitudes, however, installing more dampers results in a lower observed difference. The research includes a detailed statistical analysis of wind data and cable responses, considering different observation intervals since the observed time of development of lock-in vibrations might impact the VIV statistical indicators. It is also shown that the duration over which wind can be considered stationary most often differs from the conventional 10-minute duration. Finally, using statistical hypothesis testing, it is demonstrated that VIV metrics are slightly influenced by the observation interval length, and it is confirmed that high turbulence intensity significantly limits the amplitude reached at synchronization. Overall, this research provides valuable insights into understanding and addressing challenges related to measuring and interpreting vortex-induced vibrations on hangers.
{"title":"Advanced statistical analysis of vortex-induced vibrations in suspension bridge hangers with and without Stockbridge dampers","authors":"G. Bacci , Ø.W. Petersen , V. Denoël , O. Øiseth","doi":"10.1016/j.jweia.2024.105931","DOIUrl":"10.1016/j.jweia.2024.105931","url":null,"abstract":"<div><div>This paper presents a detailed statistical analysis of strong hanger vortex-induced vibrations (VIV) at the Hålogaland Bridge in Narvik, Norway. Severe VIV during construction led to the installation of Stockbridge dampers post-completion. Unfortunately, many dampers broke within a year, prompting a long-term measurement campaign. The measurements highlight the complexity of observed VIV, with non-stationary and multi-frequency vibrations during constant wind speeds. The paper assesses the effectiveness of various damper configurations on the hangers and finds that a single damper notably reduces vibration amplitudes, however, installing more dampers results in a lower observed difference. The research includes a detailed statistical analysis of wind data and cable responses, considering different observation intervals since the observed time of development of lock-in vibrations might impact the VIV statistical indicators. It is also shown that the duration over which wind can be considered stationary most often differs from the conventional 10-minute duration. Finally, using statistical hypothesis testing, it is demonstrated that VIV metrics are slightly influenced by the observation interval length, and it is confirmed that high turbulence intensity significantly limits the amplitude reached at synchronization. Overall, this research provides valuable insights into understanding and addressing challenges related to measuring and interpreting vortex-induced vibrations on hangers.</div></div>","PeriodicalId":54752,"journal":{"name":"Journal of Wind Engineering and Industrial Aerodynamics","volume":"255 ","pages":"Article 105931"},"PeriodicalIF":4.2,"publicationDate":"2024-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142660649","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-13DOI: 10.1016/j.jweia.2024.105947
Xiaowen Ji , Deming Li , Feng Li , Zhao-Hui Lu , Guoqing Huang
The dependence of extreme wind pressure coefficients has gained attention due to its potential impact on determining design wind loads and assessing wind-induced damages of cladding components. However, experimental data with short durations often fail to provide a sufficient number of extreme samples of pressure coefficients over specified epochs (e.g., 10 min or 1 h). Consequently, estimating the dependence of extreme pressure coefficients remains a challenge. To address this issue, Spearman's ρ is employed to quantify the dependence of extreme pressure coefficients due to their non-Gaussianity nature, based on which a theoretical formula converting the dependence of extreme pressure coefficients across different epochs is deduced. Furthermore, a simplified conversion formula, which offers accuracy equivalent to the theoretical one while enhancing efficiency, is provided. A dataset of pressure coefficients with a very long duration is employed for formula examination. The conversion formula demonstrates good agreement with the observed trend of dependence between extreme pressure coefficients over different epochs. Error analysis is also conducted to investigate the uncertainty of estimates from data. Additionally, the efficacy of the conversion formula deduced based on Pearson's linear correlation coefficient is discussed.
{"title":"Converting dependence of extreme wind pressure coefficients across different epochs","authors":"Xiaowen Ji , Deming Li , Feng Li , Zhao-Hui Lu , Guoqing Huang","doi":"10.1016/j.jweia.2024.105947","DOIUrl":"10.1016/j.jweia.2024.105947","url":null,"abstract":"<div><div>The dependence of extreme wind pressure coefficients has gained attention due to its potential impact on determining design wind loads and assessing wind-induced damages of cladding components. However, experimental data with short durations often fail to provide a sufficient number of extreme samples of pressure coefficients over specified epochs (e.g., 10 min or 1 h). Consequently, estimating the dependence of extreme pressure coefficients remains a challenge. To address this issue, Spearman's <em>ρ</em> is employed to quantify the dependence of extreme pressure coefficients due to their non-Gaussianity nature, based on which a theoretical formula converting the dependence of extreme pressure coefficients across different epochs is deduced. Furthermore, a simplified conversion formula, which offers accuracy equivalent to the theoretical one while enhancing efficiency, is provided. A dataset of pressure coefficients with a very long duration is employed for formula examination. The conversion formula demonstrates good agreement with the observed trend of dependence between extreme pressure coefficients over different epochs. Error analysis is also conducted to investigate the uncertainty of estimates from data. Additionally, the efficacy of the conversion formula deduced based on Pearson's linear correlation coefficient is discussed.</div></div>","PeriodicalId":54752,"journal":{"name":"Journal of Wind Engineering and Industrial Aerodynamics","volume":"255 ","pages":"Article 105947"},"PeriodicalIF":4.2,"publicationDate":"2024-11-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142660457","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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 : 2024-11-12DOI: 10.1016/j.jweia.2024.105954
Shizeng Liu , Wentong Zhang , Qiang Li , Shicheng Yan , Shihong Zhang , Chao Li , Lixiao Li
For transmission tower-line (TL) systems, the coupling effect between line cables and towers under strong winds is significant. This paper presents a method to quantify the coupling effect. Assuming that effective separation of line cables and towers is attainable, this work transforms the coupling effect into the transferred load from the line cable to the target tower, the coupling participation mass of the line cable, and the additional damping. The effective separation conditions are defined through an optimization method minimizing the residual errors of the wind-induced response and dynamic characteristics between the separated bodies and the TL system. A typical TL system is considered and analyzed for its structural dynamic characteristics and wind-induced response. Particularly, the quantities associated with the coupling effect of the TL system are estimated. It reveals that the transferred dynamic load component parallel to the line cable which is overlooked in current codes is significant and highly sensitive to the separation boundary conditions of line cables. Furthermore, the coupling participation mass of the conductor is more prominent than that of the ground wire. The proposed method is feasible for quantifying the TL coupling effect and incorporating it into the wind-induced response analysis of transmission line structures.
{"title":"Engineering method for quantifying the coupling effect of transmission tower-line system under strong winds","authors":"Shizeng Liu , Wentong Zhang , Qiang Li , Shicheng Yan , Shihong Zhang , Chao Li , Lixiao Li","doi":"10.1016/j.jweia.2024.105954","DOIUrl":"10.1016/j.jweia.2024.105954","url":null,"abstract":"<div><div>For transmission tower-line (TL) systems, the coupling effect between line cables and towers under strong winds is significant. This paper presents a method to quantify the coupling effect. Assuming that effective separation of line cables and towers is attainable, this work transforms the coupling effect into the transferred load from the line cable to the target tower, the coupling participation mass of the line cable, and the additional damping. The effective separation conditions are defined through an optimization method minimizing the residual errors of the wind-induced response and dynamic characteristics between the separated bodies and the TL system. A typical TL system is considered and analyzed for its structural dynamic characteristics and wind-induced response. Particularly, the quantities associated with the coupling effect of the TL system are estimated. It reveals that the transferred dynamic load component parallel to the line cable which is overlooked in current codes is significant and highly sensitive to the separation boundary conditions of line cables. Furthermore, the coupling participation mass of the conductor is more prominent than that of the ground wire. The proposed method is feasible for quantifying the TL coupling effect and incorporating it into the wind-induced response analysis of transmission line structures.</div></div>","PeriodicalId":54752,"journal":{"name":"Journal of Wind Engineering and Industrial Aerodynamics","volume":"255 ","pages":"Article 105954"},"PeriodicalIF":4.2,"publicationDate":"2024-11-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142660006","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A precise command of railway operations according to the measured instantaneous wind speed on an anemometer tower along a railway line is the development trend, whose challenges lie in the unknown transfer relation(s) between wind speed fluctuations on a moving train and an anemometer tower, i.e. the turbulence correlation between them. To address this issue, in the current work, the cross-correlation functions of wind speed fluctuations at the moving train and anemometer tower are derived, and an empirical formula of the coherence functions is obtained. The turbulence correlation is inversely related to the separation distance from the anemometer tower to the line, and there is little correlation when this distance is longer than double the longitudinal turbulence length scale. Field measurements of wind characteristics were carried out on an anemometer tower and a moving vehicle, and the turbulence correlation and its expression were validated. Three methods are proposed and compared to evaluate the instantaneous wind speed at the anemometer tower and moving train with this correlation. The methods based on the cross-spectral density and coherence function can accurately simulate the correlation, and the latter performance is slightly better (its simulation of the frequency domain correlation is 52.9% better than the former); the method based on solely independent and identically distributed random phases cannot fully simulate the correlation. From this, the effects of the correlation on train operations are studied and analysed in detail. Our analysis shows that neglecting this correlation leads to conservative estimates: wind speed differences between the anemometer tower and the moving train are at least 18.1% greater, and the safety and economic assessments of train operations in crosswinds are underestimated by at least 32.0%. Considering the correlation can reduce the (excess) safety risk/margin and is an inevitable development of adapting to the detailed assessment of the crosswind stability of vehicles. The quantitative description and simulation of the correlation presented in this work point to the critical importance of wind speed monitoring systems for the detailed crosswind assessment, and provide a theoretical basis for further research work on the crosswind stability of vehicles under true/realistic turbulent flow wind.
{"title":"Turbulence correlation between moving trains and anemometer towers: Theoretical analysis, field measurements and simulation","authors":"Hongrui Gao , Tanghong Liu , Xiaodong Chen , Haoyang Zeng , Jiyun Jiang , Xinran Wang , Boo Cheong Khoo","doi":"10.1016/j.jweia.2024.105949","DOIUrl":"10.1016/j.jweia.2024.105949","url":null,"abstract":"<div><div>A precise command of railway operations according to the measured instantaneous wind speed on an anemometer tower along a railway line is the development trend, whose challenges lie in the unknown transfer relation(s) between wind speed fluctuations on a moving train and an anemometer tower, i.e. the turbulence correlation between them. To address this issue, in the current work, the cross-correlation functions of wind speed fluctuations at the moving train and anemometer tower are derived, and an empirical formula of the coherence functions is obtained. The turbulence correlation is inversely related to the separation distance from the anemometer tower to the line, and there is little correlation when this distance is longer than double the longitudinal turbulence length scale. Field measurements of wind characteristics were carried out on an anemometer tower and a moving vehicle, and the turbulence correlation and its expression were validated. Three methods are proposed and compared to evaluate the instantaneous wind speed at the anemometer tower and moving train with this correlation. The methods based on the cross-spectral density and coherence function can accurately simulate the correlation, and the latter performance is slightly better (its simulation of the frequency domain correlation is 52.9% better than the former); the method based on solely independent and identically distributed random phases cannot fully simulate the correlation. From this, the effects of the correlation on train operations are studied and analysed in detail. Our analysis shows that neglecting this correlation leads to conservative estimates: wind speed differences between the anemometer tower and the moving train are at least 18.1% greater, and the safety and economic assessments of train operations in crosswinds are underestimated by at least 32.0%. Considering the correlation can reduce the (excess) safety risk/margin and is an inevitable development of adapting to the detailed assessment of the crosswind stability of vehicles. The quantitative description and simulation of the correlation presented in this work point to the critical importance of wind speed monitoring systems for the detailed crosswind assessment, and provide a theoretical basis for further research work on the crosswind stability of vehicles under true/realistic turbulent flow wind.</div></div>","PeriodicalId":54752,"journal":{"name":"Journal of Wind Engineering and Industrial Aerodynamics","volume":"255 ","pages":"Article 105949"},"PeriodicalIF":4.2,"publicationDate":"2024-11-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142660548","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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 : 2024-11-09DOI: 10.1016/j.jweia.2024.105933
Agostino Cembalo , Jacques Borée , Patrick Coirault , Clément Dumand
Under disturbed upstream conditions, numerous wind tunnel studies have shown that the near wake region of a vehicle loses its average symmetry, resulting in an increase of drag. The aim of this research work is to analyze the large scale response of a vehicle wake to on-road perturbations by using an instrumented vehicle and by comparing scale one wind tunnel tests, track trials and on road experiments. More precisely, in all these tests, we focus on the analysis of the asymmetry of the pressure distribution at the base. Proper Orthogonal Decomposition (POD) is used. For all cases considered, POD analysis reveals two dominant modes, respectively associated with vertical and horizontal wake large scale reorganization. More than 50% of the total energy is carried by these two modes and this value increases significantly for on-road tests. Noteworthy, the low-frequency energy content of the temporal coefficients of these modes is significantly higher on-road. Low frequencies (even very low ones) then play a major role, corresponding to a quasi-static perturbation domain of the velocity seen by the vehicle. We show that a quasi-steady exploration of the on-road yaw angle statistical distribution during a wind tunnel test captures phenomena similar to those observed on the road and is therefore interesting to evaluate on-road aerodynamic performances. This also opens perspectives for developing closed loop control strategies aiming to maintain a prescribed wake balance in order to reduce drag experienced on the road.
{"title":"Large scale response of a vehicle wake to on-road perturbations","authors":"Agostino Cembalo , Jacques Borée , Patrick Coirault , Clément Dumand","doi":"10.1016/j.jweia.2024.105933","DOIUrl":"10.1016/j.jweia.2024.105933","url":null,"abstract":"<div><div>Under disturbed upstream conditions, numerous wind tunnel studies have shown that the near wake region of a vehicle loses its average symmetry, resulting in an increase of drag. The aim of this research work is to analyze the large scale response of a vehicle wake to on-road perturbations by using an instrumented vehicle and by comparing scale one wind tunnel tests, track trials and on road experiments. More precisely, in all these tests, we focus on the analysis of the asymmetry of the pressure distribution at the base. Proper Orthogonal Decomposition (POD) is used. For all cases considered, POD analysis reveals two dominant modes, respectively associated with vertical and horizontal wake large scale reorganization. More than 50% of the total energy is carried by these two modes and this value increases significantly for on-road tests. Noteworthy, the low-frequency energy content of the temporal coefficients of these modes is significantly higher on-road. Low frequencies (even very low ones) then play a major role, corresponding to a quasi-static perturbation domain of the velocity seen by the vehicle. We show that a quasi-steady exploration of the on-road yaw angle statistical distribution during a wind tunnel test captures phenomena similar to those observed on the road and is therefore interesting to evaluate on-road aerodynamic performances. This also opens perspectives for developing closed loop control strategies aiming to maintain a prescribed wake balance in order to reduce drag experienced on the road.</div></div>","PeriodicalId":54752,"journal":{"name":"Journal of Wind Engineering and Industrial Aerodynamics","volume":"255 ","pages":"Article 105933"},"PeriodicalIF":4.2,"publicationDate":"2024-11-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142660008","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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 : 2024-11-09DOI: 10.1016/j.jweia.2024.105937
Simian Lei , Luca Patruno , Claudio Mannini , Stefano de Miranda , Yaojun Ge
Motion-induced aerodynamic forces play a fundamental role in the stability and buffeting analysis of long-span bridges, which are traditionally performed in the frequency domain adopting the well-known approach based on flutter derivatives and aerodynamic admittance functions. However, the increase in span of newly designed bridges currently raises concerns regarding the role of nonlinear aerodynamic effects, the response to non-stationary winds and the aerodynamic coupling in multi-modal vibrations. Addressing these issues requires to calculate aerodynamic forces induced by arbitrary motions and, possibly, consider large variations in the incoming flow orientation, a task better suited for time-domain approaches. In this study, we introduce a time-domain state-space model formulation for motion-induced aerodynamic forces, which systematizes and generalizes previous models, while keeping a simple structure and ease of calibration. We tailor the model formulation to allow for a clear distinction between quasi-static and purely transient aerodynamic contributions and investigate the relations between the proposed model and other available models, highlighting their common underlying framework. The model is finally calibrated for a selection of bridge decks, showing a very good ability to reproduce motion-induced aerodynamic forces.
{"title":"Time-domain state-space model formulation of motion-induced aerodynamic forces on bridge decks","authors":"Simian Lei , Luca Patruno , Claudio Mannini , Stefano de Miranda , Yaojun Ge","doi":"10.1016/j.jweia.2024.105937","DOIUrl":"10.1016/j.jweia.2024.105937","url":null,"abstract":"<div><div>Motion-induced aerodynamic forces play a fundamental role in the stability and buffeting analysis of long-span bridges, which are traditionally performed in the frequency domain adopting the well-known approach based on flutter derivatives and aerodynamic admittance functions. However, the increase in span of newly designed bridges currently raises concerns regarding the role of nonlinear aerodynamic effects, the response to non-stationary winds and the aerodynamic coupling in multi-modal vibrations. Addressing these issues requires to calculate aerodynamic forces induced by arbitrary motions and, possibly, consider large variations in the incoming flow orientation, a task better suited for time-domain approaches. In this study, we introduce a time-domain state-space model formulation for motion-induced aerodynamic forces, which systematizes and generalizes previous models, while keeping a simple structure and ease of calibration. We tailor the model formulation to allow for a clear distinction between quasi-static and purely transient aerodynamic contributions and investigate the relations between the proposed model and other available models, highlighting their common underlying framework. The model is finally calibrated for a selection of bridge decks, showing a very good ability to reproduce motion-induced aerodynamic forces.</div></div>","PeriodicalId":54752,"journal":{"name":"Journal of Wind Engineering and Industrial Aerodynamics","volume":"255 ","pages":"Article 105937"},"PeriodicalIF":4.2,"publicationDate":"2024-11-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142660005","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-08DOI: 10.1016/j.jweia.2024.105946
Congjie Shang , Huoyue Xiang , Yulong Bao , Yongle Li , Kou Luo
The long-span bridge has a flexible structure and low damping. And the truss girder section is relatively blunt, which is prone to vortex-induced vibration(VIV). Initially, the wind tunnel tests are carried out at two scales to test the two lock-in regions of VIV for the truss girder. Then, the fluid-structure coupling analysis numerical model of the simplified two-dimensional(2-D) section of the truss girder is established, and the analysis results are compared with the experiment. Finally, the time-frequency characteristics of the aerodynamic lift and the wind speed at the movable monitoring points, further the meso-mechanism of the vortex evolution in two lock-in regions are analyzed. The results indicate that there are both twice key changes in the lift frequency components during the whole process of VIV in the two lock-in regions with the increase in amplitude, which are related to the change in flow pattern. VIV in the first lock-in region is self-excited by the coupling of the wake vortex of the bridge deck and the motion of the model. VIV in the second lock-in of VIV is self-excited by the impinging shear layer instability at the leading edge of the bridge deck and the motion of the model.
{"title":"Mechanism of vortex-induced vibration in two lock-in regions for truss girder sections","authors":"Congjie Shang , Huoyue Xiang , Yulong Bao , Yongle Li , Kou Luo","doi":"10.1016/j.jweia.2024.105946","DOIUrl":"10.1016/j.jweia.2024.105946","url":null,"abstract":"<div><div>The long-span bridge has a flexible structure and low damping. And the truss girder section is relatively blunt, which is prone to vortex-induced vibration(VIV). Initially, the wind tunnel tests are carried out at two scales to test the two lock-in regions of VIV for the truss girder. Then, the fluid-structure coupling analysis numerical model of the simplified two-dimensional(2-D) section of the truss girder is established, and the analysis results are compared with the experiment. Finally, the time-frequency characteristics of the aerodynamic lift and the wind speed at the movable monitoring points, further the meso-mechanism of the vortex evolution in two lock-in regions are analyzed. The results indicate that there are both twice key changes in the lift frequency components during the whole process of VIV in the two lock-in regions with the increase in amplitude, which are related to the change in flow pattern. VIV in the first lock-in region is self-excited by the coupling of the wake vortex of the bridge deck and the motion of the model. VIV in the second lock-in of VIV is self-excited by the impinging shear layer instability at the leading edge of the bridge deck and the motion of the model.</div></div>","PeriodicalId":54752,"journal":{"name":"Journal of Wind Engineering and Industrial Aerodynamics","volume":"255 ","pages":"Article 105946"},"PeriodicalIF":4.2,"publicationDate":"2024-11-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142660456","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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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