Abstract:Link to publication on Research at Birmingham portal General rights Unless a licence is specified above, all rights (including copyright and moral rights) in this document are retained by the authors and/or the copyright holders. The express permission of the copyright holder must be obtained for any use of this material other than for purposes permitted by law. • Users may freely distribute the URL that is used to identify this publication. • Users may download and/or print one copy of the publication from th… Show more
“…It is acknowledged that there is always to some extent a difference between model-scale and full-scale results due to the disparity in Re. However, Re~10 5 has widely been regarded as a high enough value in which case the aerodynamic coefficients would be similar to those expected at full-scale, or at least the trend should be the same (Hong et al, 1998, Hargreaves and Morvan, 2007, Gallagher et al, 2018, Krajnović and Davidson, 2005b. Indeed, there is limited research available and therefore the Re effects are not conclusive, which requires more systematic study in the future.…”
Link to publication on Research at Birmingham portal General rights Unless a licence is specified above, all rights (including copyright and moral rights) in this document are retained by the authors and/or the copyright holders. The express permission of the copyright holder must be obtained for any use of this material other than for purposes permitted by law. • Users may freely distribute the URL that is used to identify this publication. • Users may download and/or print one copy of the publication from the University of Birmingham research portal for the purpose of private study or non-commercial research. • User may use extracts from the document in line with the concept of 'fair dealing' under the Copyright, Designs and Patents Act 1988 (?) • Users may not further distribute the material nor use it for the purposes of commercial gain. Where a licence is displayed above, please note the terms and conditions of the licence govern your use of this document. When citing, please reference the published version. Take down policy While the University of Birmingham exercises care and attention in making items available there are rare occasions when an item has been uploaded in error or has been deemed to be commercially or otherwise sensitive.
“…It is acknowledged that there is always to some extent a difference between model-scale and full-scale results due to the disparity in Re. However, Re~10 5 has widely been regarded as a high enough value in which case the aerodynamic coefficients would be similar to those expected at full-scale, or at least the trend should be the same (Hong et al, 1998, Hargreaves and Morvan, 2007, Gallagher et al, 2018, Krajnović and Davidson, 2005b. Indeed, there is limited research available and therefore the Re effects are not conclusive, which requires more systematic study in the future.…”
Link to publication on Research at Birmingham portal General rights Unless a licence is specified above, all rights (including copyright and moral rights) in this document are retained by the authors and/or the copyright holders. The express permission of the copyright holder must be obtained for any use of this material other than for purposes permitted by law. • Users may freely distribute the URL that is used to identify this publication. • Users may download and/or print one copy of the publication from the University of Birmingham research portal for the purpose of private study or non-commercial research. • User may use extracts from the document in line with the concept of 'fair dealing' under the Copyright, Designs and Patents Act 1988 (?) • Users may not further distribute the material nor use it for the purposes of commercial gain. Where a licence is displayed above, please note the terms and conditions of the licence govern your use of this document. When citing, please reference the published version. Take down policy While the University of Birmingham exercises care and attention in making items available there are rare occasions when an item has been uploaded in error or has been deemed to be commercially or otherwise sensitive.
“…The correctness and effectiveness of this system was proven by He et al 6 This system can separately and simultaneously measure the aerodynamic performances of the train and the bridge. Gallagher et al 28 confirmed that Re ¼ 1.4 Â 10 5 is enough to predict the side force coefficient of the train by comparing full-scale measurements and wind tunnel tests.…”
Section: Validation Of the Numerical Methodsmentioning
confidence: 96%
“…Gallagher et al. 28 confirmed that Re = 1.4 × 10 5 is enough to predict the side force coefficient of the train by comparing full-scale measurements and wind tunnel tests. Figure 4.Comparison of the wind tunnel tests and numerical simulations: (a) experimental model, (b) measurement system, (c) bridge coefficients, and (d) train coefficients.…”
Section: Validation Of the Numerical Methodsmentioning
This paper investigates the effect of a wind barrier on the aerodynamic performance of a train–bridge system under crosswind using a numerical simulation method. The studied bridge is a long-span cable-stayed bridge with a flat steel box girder, located in Chongqing, China. The flow field around the train–bridge system with and without a wind barrier is numerically simulated. Wind barrier porosities varying from 10 to 60% are evaluated. The tricomponent coefficients of the train, bridge, and train–bridge system are obtained and investigated in detail. The effect of the wind barrier on the aerodynamics of the train–bridge system is revealed through the determination of the aerodynamic forces, pressure mapping, and flow visualization. The results show that a wind barrier successfully decreases the mean velocity above the girder and consequently decreases the drag force and moment on the train; however, the wind barrier also significantly increases the drag force on the girder. Therefore, installation of a wind barrier improves the running safety of the train but is detrimental to the wind resistance of the bridge. Additionally, the efficiency of the wind barrier depends on the porosity. A lower porosity improves the train safety but is more detrimental to the bridge safety. An optimal wind barrier porosity of 30% is obtained based on the aerodynamic forces of both the train and the bridge. Compared to a train–bridge system without a wind barrier, the drag force and moment on the train decrease by 66.1 and 62.9%, respectively; the drag force on the bridge girder increases to 0.86, and the drag force on the train–bridge system equals that without the wind barrier.
“…There have been many pieces of research to estimate the aerodynamic behaviors of the train under a crosswind environment using the full-scale experiments, scaled wind tunnel tests and CFD simulations CONTACT Nan Zhang nzhang@bjtu.edu.cn (Alonso-Estébanez, Del Coz Díaz, Álvarez Rabanal, & Pascual-Muñoz, 2017;Baker, Jones, Lopez-Calleja, & Munday, 2004;Gallagher et al, 2018;Niu, Zhou, & Liang, 2018;Suzuki, Tanemoto, & Maeda, 2003). In these investigations, usually the train runs on the flat ground or embankment, and the movement of the train is created by means of the resultant velocity V r imposed on a static vehicle, as seen in Figure 1, depending on the train speed V t and incoming wind speed V w with a wind angle of α.…”
Section: Introductionmentioning
confidence: 99%
“…Based on all the problems mentioned above, it is necessary to study and discuss the aerodynamic characteristics of the train-bridge system with a moving train model. Generally known, it is difficult and complex to carry out a full-scale experiment to estimate the aerodynamic characteristics of the moving train owing to the unpredictable natural environment, expensive cost and long test period (Baker et al, 2004;Gallagher et al, 2018). For a scaled wind tunnel test in connection with a moving train, Baker (1986) initially developed a moving model rig to explore the forces on the advanced passenger train subjected to an atmospheric boundary layer and then, the train model accelerated by the gravity and traveling along the u-shaped guideway was applied by Bocciolone, Cheli, Corradi, Muggiasca, and Tomasini (2008).…”
Some aerodynamic results about the effect of moving train on the aerodynamics of train-bridge system in crosswinds are introduced using a computational fluid dynamics (CFD) method. In the simulation, a new overset mesh approach is applied to present the motion of trains, and the results are compared with that of the scaled wind tunnel experiment to validate the accuracy of the mesh and algorithm. Besides, the aerodynamic characteristics associated with the train and bridge are discussed for a range of resultant yaw angles. It is found that the resultant yaw angle is significantly important for the aerodynamic performances of trains, and the aerodynamic interaction on the nose of head-car can affect the flow features around train-bridge system to produce larger aerodynamic loads on the head-car. Furthermore, a new fitting formula for some resultant yaw angles is proposed to predict the aerodynamic forces on trains. Finally, the time-varying forces on the bridge are presented and a sudden change of aerodynamic loads is also observed due to the effect of moving train. The variation magnitude of forces depends on the train speed, and the mean value of forces is only determined by the natural wind velocity.
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