The Effect of the Nose Length on the Aerodynamics of a High-Speed Train Passing Through a Noise Barrier

Meng, Shuang; Zhou, Dan; Xiong, Xiaohui; Guang, Chen

doi:10.1007/s10494-021-00284-9

Cited by 18 publications

(3 citation statements)

References 36 publications

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“…The peak pressure of the head wave in the numerical simulation closely approximates that observed in the in-situ test. These results affirm that the calculation methods and parameters employed in this study can accurately replicate the actual pressure distribution on the sound barrier [32]. Further parametric analyses can be conducted utilizing the aforementioned CFD modeling method.…”

Section: Model Validationsupporting

confidence: 71%

Numerical Simulation of Aerodynamic Pressure on Sound Barriers from High-Speed Trains with Different Nose Lengths

Jin,

Liu,

2024

Applied Sciences

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For high-speed railway sound barriers, determining the aerodynamic pressure generated by high-speed trains is crucial for their structural design. This paper investigates the distribution of aerodynamic pressure on the sound barrier caused by high-speed trains with different nose lengths, utilizing the computational fluid dynamics (CFD) simulation method. The accuracy of the numerical simulation method employed is verified through comparison with field test results from the literature. Research findings reveal that when a high-speed train passes through a sound barrier, significant “head wave” and “wake wave” effects occur, with the pressure peak of the “head wave” being notably greater than that of the “wake wave”. As the distance between the sound barrier and the center of the train gradually increases, the aerodynamic pressure on the sound barrier gradually decreases. The nose length of the train has a considerable impact on the aerodynamic pressure exerted on the sound barrier. The streamlined shape of longer-nose trains can significantly reduce the aerodynamic effects on the sound barrier, resulting in a notably smaller pressure peak compared to shorter-nose trains. Finally, by establishing the relationship between the train nose length and the aerodynamic pressure peak, a calculation formula for the train-induced aerodynamic pressure acting on the sound barrier is proposed, taking into account the nose length of the high-speed train.

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Section: Model Validationsupporting

confidence: 71%

Numerical Simulation of Aerodynamic Pressure on Sound Barriers from High-Speed Trains with Different Nose Lengths

Jin,

Liu,

2024

Applied Sciences

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“…This study demonstrates the necessity of including a physics-informed time delay in the MDP and the benefits of introducing ARP to achieve a robust and temporal-coherent control of unsteady forces in active flow control. Reduction of high-level temporal fluctuations in drag or lift will help to decrease dynamic loads and structural fatigue leading to an improved structural durability and operational safety [51][52][53] .…”

Section: Introductionmentioning

confidence: 99%

Active flow control using deep reinforcement learning with time delays in Markov decision process and autoregressive policy

2022

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Classical active flow control (AFC) methods based on solving the Navier-Stocks equations are laborious and computationally intensive even with the use of reduced-order models. Data-driven methods offer a promising alternative for AFC and have been applied successfully to reduce the drag of two-dimensional bluff bodies using deep reinforcement learning (DRL) paradigms. However, the standard DRL method tends to result in large fluctuations in the unsteady forces acting on the cylinder as the Reynolds number increases. In this study, a Markov decision process (MDP) with time delays is introduced to quantify the action delays in the DRL process along with the use of a first-order autoregressive policy (ARP). This hybrid DRL method is applied to control the vortex shedding process from a two-dimensional circular cylinder with four synthetic jet actuators at a freestream Reynolds number of 400. Compared to the standard DRL method, this method is shown to reduce the magnitude of drag and lift fluctuations by approximately 90% at the same actuation frequency while achieving a similar level of drag reduction. Although both methods suppress the vortex-induced forces by extending the recirculation zone behind the circular cylinder, the hybrid method leads to a steadier and more elongated recirculation zone, and hence a weaker vortex shedding process. This study demonstrates the necessity of accurately quantifying the delay in the MDP and the benefits of introducing ARPs to achieve a smooth control of unsteady forces in AFC.

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“…Therefore, the optimization of the train nose shape is an effective measure for improving the aerodynamic performance of trains (Chen et al 2018;Niu et al 2018). Extensive research has been conducted to investigate the effects of the nose shape of a train on its aerodynamic characteristics (Meng et al 2022(Meng et al , 2021bXie et al 2019).…”

Section: Introductionmentioning

confidence: 99%

Numerical Analysis of the Effect of Streamlined Nose Length on Slipstream of High-Speed Train Passing through a Tunnel

2022

JAFM

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The improved delayed detached eddy simulation (IDDES) method was employed based on the shear-stress transport (SST) - two-equation turbulence model to simulate the slipstream distribution characteristics of a high-speed train traversing a tunnel. The accuracy of the numerical simulation method was verified through a full-scale test. First, the wake vortex structure and the distribution of slipstreams of the train with a streamlined nose length of 7 m running in a tunnel were analyzed. Then, the influence of the streamlined nose length on the wake dynamics and slipstream was compared and analyzed. The slipstream positive peak decreased with increasing distance from the top of the rail and center of the track. As the streamlined nose length increases, the vortex intensity in the wake area weakens; moreover, the influence ranges of the wake vortex and the slipstream positive peak value become smaller. Compared with the results of a train having a streamlined nose length of 5 m, the slipstream positive peak value at 1.4 m from the top of the rail and 100 m from the tunnel entrance decreased by 46.6% from that of a train with a streamlined nose length of 9 m.

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The Effect of the Nose Length on the Aerodynamics of a High-Speed Train Passing Through a Noise Barrier

Cited by 18 publications

References 36 publications

Numerical Simulation of Aerodynamic Pressure on Sound Barriers from High-Speed Trains with Different Nose Lengths

Numerical Simulation of Aerodynamic Pressure on Sound Barriers from High-Speed Trains with Different Nose Lengths

Active flow control using deep reinforcement learning with time delays in Markov decision process and autoregressive policy

Numerical Analysis of the Effect of Streamlined Nose Length on Slipstream of High-Speed Train Passing through a Tunnel

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