Numerical Simulation of Thixo-co-Extrusion of 7075/AZ91D Double-Layer Tubes

2016 ◽  
Vol 256 ◽  
pp. 119-125
Author(s):  
Xiao Wei Li ◽  
Kai Kun Wang ◽  
Jin Long Fu ◽  
Fei Yin
Keyword(s):  
Numerical Simulation ◽  
Double Layer ◽  
High Speed ◽  
New Technology ◽  
High Strength ◽  
Temperature Fields ◽  
Atomic Diffusion ◽  
Magnetic Pulse ◽  
High Speed Trains ◽  
Contact Pressures

Due to the excellent thermal conductivity and high strength of aluminum alloy and unique advantages containing shock absorbing, vibrations dampening and corrosion resistant of magnesium alloy, Al/Mg double-layer tubes have been widely utilized in household appliances, automobiles, aerospace industries, and high-speed trains in recent years. Conventionally, double-layer tubes are produced by welding, extrusion, hydroforming, magnetic pulse cladding. These processes are either complex or highly energy-consuming. To improve efficiency and reduce energy consumption, a new technology, thixo-co-extrusion (TCE), is put forward for production of double-layer tubes. In this paper, the thixo-co-extrusion of a 7075/AZ91D double-layer tube is investigated by numerical simulation. This study assesses the influences of extrusion velocity, the thickness ratios of two layers, the reheating temperatures of billets and the preheating temperature of die on the flow behaviors. The results show that the extrusion velocity and the thickness ratios significantly influence the contact pressures on the interface as well as the velocity fields. Besides, the reheating temperatures of billets and the preheating temperatures determine the distribution of temperature fields. Under the contact pressures and a certain temperature, atomic diffusion takes place on the interface between inner and outer layer, which leads to metallurgical bonding of the interface. The paper contributes to a better understanding of the thixo-co-extrusion technology for the production of double-layer tubes with desirable mechanical properties.

Numerical Simulation of Flowfield around High Speed Trains Passing by each other at the same Speed

2011 ◽  
Vol 97-98 ◽  
pp. 698-701
Author(s):  
Ming Lu Zhang ◽  
Yi Ren Yang ◽  
Li Lu ◽  
Chen Guang Fan
Keyword(s):  
Numerical Simulation ◽  
Wind Tunnel ◽  
Flow Field ◽  
Point Source ◽  
High Speed ◽  
Stokes Equations ◽  
Field Structure ◽  
Vehicle Speed ◽  
Mesh Method ◽  
High Speed Trains

Large eddy simulation (LES) was made to solve the flow around two simplified CRH2 high speed trains passing by each other at the same speed base on the finite volume method and dynamic layering mesh method and three dimensional incompressible Navier-Stokes equations. Wind tunnel experimental method of resting train with relative flowing air and dynamic mesh method of moving train were compared. The results of numerical simulation show that the flow field structure around train is completely different between wind tunnel experiment and factual running. Two opposite moving couple of point source and point sink constitute the whole flow field structure during the high speed trains passing by each other. All of streamlines originate from point source (nose) and finish with the closer point sink (tail). The flow field structure around train is similar with different vehicle speed.

Numerical simulation of two opposing high speed trains in a tunnel

1995 ◽  
Author(s):  
S Ramakrishnan ◽  
C Chen ◽  
S Chakravarthy ◽  
K Szema ◽  
D Vitali
Keyword(s):  
Numerical Simulation ◽  
High Speed ◽  
High Speed Trains

scholarly journals Numerical analysis of aerodynamic noise from pantograph in high-speed trains using lattice Boltzmann method

2019 ◽  
Vol 11 (7) ◽  
pp. 168781401986399 ◽  
Author(s):  
Hee-Min Noh
Keyword(s):  
Numerical Simulation ◽  
Numerical Analysis ◽  
Lattice Boltzmann Method ◽  
Lattice Boltzmann ◽  
High Speed ◽  
Aerodynamic Noise ◽  
Noise Generation ◽  
Noise Sources ◽  
High Speed Trains ◽  
Boltzmann Method

A pantograph in contact with a catenary for power supply is one of the major aerodynamic noise sources in high-speed trains. To reduce pantograph noise, it is essential to understand the noise generation mechanism of the pantograph. However, it is difficult to determine this mechanism through measurement. Therefore, in this study, the aerodynamic and acoustic performances of a pantograph in a high-speed train were investigated through numerical analysis using the lattice Boltzmann method. First, a real-scaled pantograph was modeled through computer-aided design. Then, the surface and volume meshes of the pantograph model were generated for simulation analysis. Numerical simulation was conducted at a speed of 300 km/h based on the lattice Boltzmann method. Based on the time derivative analysis of flow pressures, it was concluded that the panhead, joint, and base were the dominant noise sources in the pantograph. In particular, various vortexes were generated from the metalized carbon strip of the panhead. The peaks of the sound pressure level propagated from the panhead were 242, 430, and 640 Hz. The noise generation mechanism was analyzed through numerical simulation using noise characteristics.

Numerical Simulation of Effect of Nose Shape on Tunnel Entry/Exit Wave Induced by a High-Speed Train Passing through a Tunnel

2011 ◽  
Vol 97-98 ◽  
pp. 712-715
Author(s):  
Jian Lin Xu ◽  
Yuan Gui Mei ◽  
Fan Yang ◽  
Xin Liu
Keyword(s):  
Numerical Simulation ◽  
High Speed ◽  
Three Dimensional ◽  
Simple Algorithm ◽  
High Speed Train ◽  
High Speed Trains ◽  
Nose Shape ◽  
Volume Method ◽  
Wave Induced ◽  
Tunnel Entrance

The air flow around the high-speed train passing through a tunnel is three dimensional, compressible and unsteady in nature. This paper carried out the numerical simulation of it and evaluated the effect of nose shapes of high-speed trains on tunnel entry/exit waves radiated directly from tunnel entrance or exit. The elliptical, parabolic and conical nose shapes were analyzed. A commercial CFD code STAR-CD based on the finite volume method was used applying the SIMPLE algorithm and a moving grid technology. The comparison study shows that though the patterns of tunnel entry waves or exit waves induced by high-speed trains with above three nose shapes are similar, the amplitudes of them are different. The wave amplitude of elliptical shape is the highest, and that of conical shape is the lowest, which implies that with the nose shape be more streamlined and slender, it might be more likely to reduce the amplitudes of tunnel entry/exit waves.

scholarly journals The Penetration–Explosion Effects of Differently Distributed Inactive/Active Composite Shaped Charge Jets

Materials ◽  
2022 ◽  
Vol 15 (1) ◽  
pp. 344
Author(s):  
Jiacheng Peng ◽  
Jianwei Jiang ◽  
Jianbing Men ◽  
Jinlin Li ◽  
Dongkang Zhou ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Double Layer ◽  
High Speed ◽  
Shaped Charge ◽  
The Other ◽  
High Speed Photography ◽  
Active Composite ◽  
Deformation Area ◽  
Full Height

An analysis of the penetration–explosion (PE) effects of four distributions of inactive/active composite jets shows that a well-designed inactive/active double-layer liner can promote composite jet damage. Penetration experiments were then carried out for shaped charge jets having a single inactive (Cu) liner or an inactive/active (Cu/Al) double-layer liner with variable liner height. The behaviors and firelight patterns of the different jets were captured by high-speed photography. The perforation, deformation area, and deflection were measured for each plate, showing that the Cu/Al jets have stronger PE effects. Numerical simulation shows that the tip of the composite jet generated from the full-height liner is only Cu, whereas for the other jet, from the double-layer liner, Cu is almost wrapped entirely by Al.

Numerical simulation of dynamic effects of high-speed trains on bridges

2003 ◽  
Vol 87 (10) ◽  
pp. 22-29
Author(s):  
J.-P. Rammant ◽  
H. Oogink ◽  
G. Vanstraelen
Keyword(s):  
Numerical Simulation ◽  
High Speed ◽  
Dynamic Effects ◽  
High Speed Trains

Numerical Simulation of Aerodynamic Behaviors of High-Speed Trains Crossing

2012 ◽  
Vol 562-564 ◽  
pp. 1390-1393
Author(s):  
Yong Chang Zhang ◽  
Yu Gong Xu ◽  
Fang Qin ◽  
Rui Cao
Keyword(s):  
Numerical Simulation ◽  
Pressure Wave ◽  
High Speed ◽  
Value Change ◽  
High Speed Train ◽  
Operating Condition ◽  
Uniform Velocity ◽  
High Speed Trains ◽  
Calculation Results ◽  
Peak Value

A model of CRH2 high-speed train has been established and the aerodynamics process of moving high-speed trains has been numerically simulated by using moving gird technology of CFdesign, Two kinds of operating condition, both trains have uniform and un-uniform velocity, were considered to analyze the aerodynamics pressure on the surfaces of the train. Finally, according to the calculation results, regularity of how the position where the highest pressure wave was located and its peak value change with the velocity increasing is concluded.

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