Investigation on flow field structure and aerodynamic load in vacuum tube transportation system

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.

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Development of a flow field structure in the vicinity of a circular cylinder in the presence of a laminar-turbulent transition

High Temperature ◽

10.1007/bf02755926 ◽

2000 ◽

Vol 38 (5) ◽

pp. 732-741

Author(s):

V. A. Bashkin ◽

I. V. Egorov ◽

M. V. Egorova ◽

D. V. Ivanov

Keyword(s):

Circular Cylinder ◽

Flow Field ◽

Field Structure ◽

Turbulent Transition ◽

Laminar Turbulent Transition

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Design and optimization of a novel composite bionic flow field structure using three-dimensional multiphase computational fluid dynamic method for proton exchange membrane fuel cell

Energy Conversion and Management ◽

10.1016/j.enconman.2021.114707 ◽

2021 ◽

Vol 247 ◽

pp. 114707

Author(s):

Lei Xia ◽

Zeting Yu ◽

Guoping Xu ◽

Shaobo Ji ◽

Bo Sun

Keyword(s):

Fuel Cell ◽

Flow Field ◽

Proton Exchange Membrane ◽

Dynamic Method ◽

Fluid Dynamic ◽

Three Dimensional ◽

Field Structure ◽

Proton Exchange ◽

Design And Optimization ◽

Exchange Membrane

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The flow field structure at the base of lifted turbulent partially premixed jet flames

Experimental Thermal and Fluid Science ◽

10.1016/j.expthermflusci.2003.12.015 ◽

2004 ◽

Vol 28 (7) ◽

pp. 771-779 ◽

Cited By ~ 15

Author(s):

Mohy S Mansour

Keyword(s):

Flow Field ◽

Field Structure ◽

Jet Flames ◽

Partially Premixed

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EFFECT OF GALLERIES ON THE WIND FLOW STRUCTURE AND POLLUTANT TRANSPORT WITHIN STREET CANYONS WITH OR WITHOUT FACADE ROUGHNESS ELEMENTS (BALCONIES)

International Journal of Engineering Technologies and Management Research ◽

10.29121/ijetmr.v7.i12.2020.835 ◽

2020 ◽

Vol 7 (12) ◽

pp. 45-59

Author(s):

V. A. Karkoulias ◽

P. E. Marazioti ◽

D. P. Georgiou ◽

E. A. Maraziotis

Keyword(s):

Flow Field ◽

Concentration Distribution ◽

Cfd Simulation ◽

Field Structure ◽

Flow Structures ◽

Street Canyons ◽

Ansys Fluent ◽

Roughness Elements ◽

Computational Fluid Dynamics Cfd ◽

The Vertical Distribution

This paper investigates how the structure of the flow field and the vertical distribution of the pollutant concentration near the wall facades of street canyons are affected by the presence of some elements such as street level galleries. Numerical results are presented for various gallery geometries in combination with facade roughness elements (balconies) for a canyon of an aspect ratio equal to h/w=2.33. The results were obtained by a Computational Fluid Dynamics (CFD) simulation employing the ANSYS-FLUENT suite that incorporated the k-e turbulent (RNG) model. The simulation generated several flow structures inside the canyon (mainly vortices), whose characteristic properties (e.g. number, strength and size) are discussed in terms of the effect of the galleries on the flow field structure and the roughness generated by the building façade balconies. The results indicate a significant influence on both the flow field structure and the mass concentration distribution of the polluting particles.

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The correspondence between flow-field structure and critical states on a 65-degree delta wing

10.2514/6.1998-4520 ◽

1998 ◽

Cited By ~ 1

Author(s):

Gregory Addington ◽

Robert Nelson

Keyword(s):

Flow Field ◽

Delta Wing ◽

Field Structure ◽

Critical States

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Experimental study on axially non-uniform clearances in a linear turbine cascade with a cavity squealer tip

Proceedings of the Institution of Mechanical Engineers Part G Journal of Aerospace Engineering ◽

10.1177/0954410018759837 ◽

2018 ◽

Vol 233 (5) ◽

pp. 1645-1655

Author(s):

Shaowen Chen ◽

Qinghe Meng ◽

Weihang Li ◽

Zhihua Zhou ◽

Songtao Wang

Keyword(s):

Flow Field ◽

Buffer Zone ◽

Aerodynamic Performance ◽

Field Structure ◽

Tip Clearance ◽

Turbine Cascade ◽

Tip Leakage Flow ◽

Tip Leakage ◽

Passage Vortex ◽

Flow Loss

The effects of axially non-uniform clearances on the tip leakage flow and aerodynamic performance in a linear turbine cascade with a cavity squealer tip were investigated in this study with the objective of improving the flow loss and tip flow field structure. A calibrated five-hole probe was used for the measurement of three-dimensional flows downstream of the cascade. The method of oil-flow visualization was used to show the endwall flow field structure. The distribution of endwall static pressure was measured particularly by using the special moveable endwall. The axially non-uniform clearance, as a novel strategy that has a non-negligible influence on tip clearance flow and clearance leakage loss, may become a potential technology for improving aerodynamic performance in turbine cascades. By using the expanding clearance, the flow loss at the outlet is reduced effectively and an apparent improvement of aerodynamic performance in the turbine cascade is gained. Under the tip clearances of 0.75% H and 2% H, the maximum reduction of overall total pressure loss coefficient at the outlet is separately about 2.3% and 3.5% compared with the uniform clearance. The shrinkage of the buffer zone is considered to be able to weaken the interaction of the tip leakage vortex and passage vortex and thus reduce the loss of passage vortex. For the shrinking clearance, a noticeable decline in the aerodynamic performance of turbine cascade with cavity squealer tip is exhibited at both on and off design conditions in contrast to the uniform clearance. In addition, the effects of axially non-uniform clearances on the aerodynamic performance at off-design conditions have been investigated.

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Flow Characteristics of a Rich-Quench-Lean Combustor-Combined Low-Emission and High-Temperature Rise Combustion

International Journal of Aerospace Engineering ◽

10.1155/2019/4014120 ◽

2019 ◽

Vol 2019 ◽

pp. 1-22

Author(s):

Jianzhong Li ◽

Jian Chen ◽

Li Yuan ◽

Ge Hu ◽

Jianhan Feng

Keyword(s):

High Temperature ◽

Flow Field ◽

Residence Time ◽

Temperature Rise ◽

Recirculation Zone ◽

Flow Characteristics ◽

Field Structure ◽

Low Emission ◽

The Rich ◽

High Temperature Rise

To determine the flow field structure and flow characteristics of a rich-quench-lean (RQL) combustor-combined low-emission and high-temperature rise combustion, a two-dimensional PIV technology was used to evaluate the effect of aerodynamic and structural parameters on the flow field and flow characteristics of the combustor. The variation in the total pressure loss of the combustor has little effect on the flow field structure of the combustor. However, the variation in the parameters of primary holes significantly affects the structure of the central recirculation zone, the distribution of local recirculation zones in the rich-burn zone and quenching zone, and the average residence time in the quenching zone. On the plane that passes through the center of the primary hole, the variations in the array mode and diameter of primary holes would form entrainment vortexes with different characteristics, thus affecting the position and flow state of local recirculation in the rich-burn zone and the local structure of the central recirculation zone. As the rotational direction of local recirculation coincides with that of the main air flow in the primary zone, the local center recirculation is intensified. In contrast, it is weakened. As the primary holes are located at half height (H/2) of the combustor, the residence time of air flow at the quenching zone can be shortened by 65% through using the staggered structure of primary holes and increasing the momentum of the partial single-hole jet. The quick-mixing process in the quenching zone is not beneficial to increase the number of primary holes and decrease the momentum of the single-hole jet.

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