Influence of Marshalling Length on Aerodynamic Characteristics of Urban Emus under Crosswind

Liang, Hongqin; Sun, Y.; Li, Ting; Zhang, J.

doi:10.47176/jafm.16.01.1338

Cited by 8 publications

(5 citation statements)

References 17 publications

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“…the present study did not consider the effect of aerodynamic forces, which has a more significant effect on high-speed trains, namely, those achieving speeds faster than 300 km/h, which is not the case in this experimental research [60]. Nevertheless, it should be highlighted that since AP and IC trains have different structural designs, their aerodynamic behaviours are different, which may have a distinct influence on their vibration levels [61].…”

Section: Maintenance Needs Identified By the Indirect Methodsmentioning

confidence: 80%

Indirect Assessment of Railway Infrastructure Anomalies Based on Passenger Comfort Criteria

et al. 2023

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Railways are among the most efficient and widely used mass transportation systems for mid-range distances. To enhance the attractiveness of this type of transport, it is necessary to improve the level of comfort, which is much influenced by the vibration derived from the train motion and wheel-track interaction; thus, railway track infrastructure conditions and maintenance are a major concern. Based on discomfort levels, a methodology capable of detecting railway track infrastructure failures is proposed. During regular passenger service, acceleration and GPS measurements were taken on Alfa Pendular and Intercity trains between Porto (Campanhã) and Lisbon (Oriente) stations. ISO 2631 methodology was used to calculate instantaneous floor discomfort levels. By matching the results for both trains, using GPS coordinates, 12 track section locations were found to require preventive maintenance actions. The methodology was validated by comparing these results with those obtained by the EM 120 track inspection vehicle, for which similar locations were found. The developed system is a complementary condition-based maintenance tool that presents the advantage of being low-cost while not disturbing regular train operations.

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Section: Maintenance Needs Identified By the Indirect Methodsmentioning

confidence: 80%

Indirect Assessment of Railway Infrastructure Anomalies Based on Passenger Comfort Criteria

et al. 2023

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“…As for the wheel surface, a rotating motion is considered with a specified angular speed. To simulate the flow characteristics, the SST turbulence model is chosen, given its widespread usage in the industry for modeling vehicle flows [20]. The SIMPLE algorithm and second-order discretization method are employed to obtain the flow field and pressure distributions accurately.…”

Section: Calculation Domain and Boundary Conditionsmentioning

confidence: 99%

Parametric Optimization of Wheel Spoke Structure for Drag Reduction of an Ahmed Body

Zhai,

Jiao,

Zhou

2024

CMES

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The wheels have a considerable influence on the aerodynamic properties and can contribute up to 25% of the total drag on modern vehicles. In this study, the effect of the wheel spoke structure on the aerodynamic performance of the isolated wheel is investigated. Subsequently, the 35°Ahmed body with an optimized spoke structure is used to analyze the flow behavior and the mechanism of drag reduction. The Fluent software is employed for this investigation, with an inlet velocity of 40 m/s. The accuracy of the numerical study is validated by comparing it with experimental results obtained from the classical Ahmed model. To gain a clearer understanding of the effects of the wheel spoke parameters on the aerodynamics of both the wheel and Ahmed model, and five design variables are proposed: the fillet angle α, the inside arc radius R 1 , the outside radius R 2 , and the same length of the chord L 1 and L 2 . These variables characterize the wheel spoke structure. The Optimal Latin Hypercube design method is utilized to conduct the experimental design. Based on the simulation results of various wheel spoke designs, the Kriging model and the adaptive simulated annealing algorithm is selected to optimize the design parameters. The objective is to achieve the best combination for maximum drag reduction. It is indicated that the optimized spoke structure resulted in a maximum drag reduction of 5.7% and 4.7% for the drag coefficient of the isolated wheel and Ahmed body, respectively. The drag reduction is primarily attributed to changes in the flow state around the wheel, which suppressed separation bubbles. Additionally, it influenced the boundary layer thickness around the car body and reduced the turbulent kinetic energy in the wake flow. These effects collectively contributed to the observed drag reduction.

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“…In particular, vehicles having a geometry with a cross section characterised by rounded forms, without sharp edges, show aerodynamic coefficients very sensitive to the flow conditions and, specifically, to the turbulence intensity [14,15]. The marshalling length of the train has been also reported to have an impact on the aerodynamic loads, especially for tail and intermediate cars, but negligible for the head car [16]. In general, even if tests are compliant with European Standard in terms of Re number and turbulence intensity, flow behaviours detected by wind tunnel tests/CFD analysis could be significantly different with respect to that occurs at full-scale conditions and consequently, the evaluated aerodynamic coefficients could not completely be representative of the real situation and may lead to wrong conclusions about the safety of the train.…”

Section: Introductionmentioning

confidence: 99%

Evaluation of the Aerodynamic Effect of a Smooth Rounded Roof on Crosswind Stability of a Train by Wind Tunnel Tests

2022

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The advent of high-speed trains led to new issues and constraints for railway network manufacturers and operators. This is the case of crosswind effect, that occurs when train is running in strong wind conditions. The combination of train speed and wind speed generates a relative flow that affects the train stability. Wind tunnel tests on still railway vehicles (relative wind-train velocity in coincidence with absolute wind velocity) are mandatory according to Technical Specification for Interoperability (TSI) to ensure high-speed train safety. However, issues related to the correct evaluation of the full-scale aerodynamic behaviour of the trains can arise. In the present work, aerodynamic force and pressure coefficients measured in wind tunnel tests on a scaled model of ETR1000 high-speed train on single track ballast and rails are presented. The tests were performed in the GVPM wind tunnel of Politecnico di Milano. Results show that different flow behaviours can occur at high yaw angles when the train behaves like a bluff body depending on wind speed used during the test.

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Influence of Marshalling Length on Aerodynamic Characteristics of Urban Emus under Crosswind

Cited by 8 publications

References 17 publications

Indirect Assessment of Railway Infrastructure Anomalies Based on Passenger Comfort Criteria

Indirect Assessment of Railway Infrastructure Anomalies Based on Passenger Comfort Criteria

Parametric Optimization of Wheel Spoke Structure for Drag Reduction of an Ahmed Body

Evaluation of the Aerodynamic Effect of a Smooth Rounded Roof on Crosswind Stability of a Train by Wind Tunnel Tests

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