\n High-speed railway aerodynamics is the key basic science for solving the bottleneck problem of high-speed railway development. This paper systematically summarizes the aerodynamic research relating to China’s high-speed railway network. Seven key research advances are comprehensively discussed, including train aerodynamic drag-reduction technology, train aerodynamic noise-reduction technology, train ventilation technology, train crossing aerodynamics, train/tunnel aerodynamics, train/climate environment aerodynamics, and train/human body aerodynamics. Seven types of railway aerodynamic test platform built by Central South University are introduced. Five major systems for a high-speed railway network—the aerodynamics theoretical system, the aerodynamic shape (train, tunnel, and so on) design system, the aerodynamics evaluation system, the 3D protection system for operational safety of the high-speed railway network, and the high-speed railway aerodynamic test/computation/analysis platform system—are also introduced. Finally, eight future development directions for the field of railway aerodynamics are proposed. For over 30 years, railway aerodynamics has been an important supporting element in the development of China’s high-speed railway network, which has also promoted the development of high-speed railway aerodynamics throughout the world.

Review of research on high-speed railway aerodynamics in China

Hydrodynamic performance of a dual-floater hybrid system combining a floating breakwater and an oscillating-buoy type wave energy converter

The aerodynamics and flow physics of a NACA 4412 airfoil in ground effect for a wide range of angles of attack from −4 to 20 deg are investigated by numerical simulations. The compressible Reynolds-averaged Navier–Stokes equations and shear-stress transport k-ω turbulence model equations are solved using the finite-volume method. Analyses of the computed results show that the angle of attack versus height (above the ground) plane can be divided into three regions based on the sign of the lift increment value: region I of positive ground effect, and regions II and III of negative ground effect. For low-to-moderate angles of attack, when the ride height is reduced, the airflow is blocked in the convergent passage between the lower surface of the airfoil and the ground, resulting in increase of pressure on the lower surface of the airfoil. As a consequence, the effective angle of attack decreases, and there is less upward deflection of the streamlines, resulting in an increase in pressure on the upper surfac...

Airfoil Aerodynamics in Ground Effect for Wide Range of Angles of Attack

https://purehost.bath.ac.uk/ws/files/200258627/Final_Revised_Manuscript_with_no_Changes_Marked.pdf

Hydrodynamic performance of a floating breakwater as an oscillating-buoy type wave energy converter

Ship stability, dynamics and safety : Status and perspectives from a review of recent STAB conferences and ISSW events

Numerical simulation of vertical water impact of asymmetric wedges by using a finite volume method combined with a volume-of-fluid technique

The performance of a wing-in-ground effect craft depends mostly on its wing configuration. The aerodynamic characteristics of compound wings were numerically investigated during the ground effect. The compound wing was divided into three parts with one rectangular wing in the middle and two reverse taper wings with anhedral angle at the sides. The NACA 6409 airfoil was employed as a section of wings. Three-dimensional computational fluid dynamics was applied as a computational scheme. The k-"turbulent model was used for the turbulent ?ow over wing surface. The computational results of a rectangular wing with aspect ratio 1, angle of attack 2 deg, and different ground clearance were compared with the experimental data of other published work. Next, the principal aerodynamic characters of compound wings and a rectangular wing were computed for various ground clearance. The aerodynamic characters of compound wings were compared with the rectangular wing, which has an acceptable increase in lift and decrease in drag. Consequently, the lift-to-drag ratio has a considerable improvement especially in small ground clearance, although their nose-down pitching moment has a little reduction. The performance of the wing improves noticeably for a certain total span of compound wing when the span of the middle part becomes smaller.

http://www.fkm.utm.my/~azwadi/pdf_publication/ISI8.pdf

Numerical Investigation on Aerodynamic Characteristics of a Compound Wing-in-Ground Effect

The aerodynamic characteristics of the wing-in-ground effect (WIG) craft model that has a noble configuration of a compound wing was experimentally investigated and Universiti Teknologi Malaysia (UTM) wind tunnel with and without endplates. Lift and drag forces, pitching moment coefficients, and the centre of pressure were measured with respect to the ground clearance and the wing angle of attack. The ground effect and the existence of the endplates increase the wing lift-to-drag ratio at low ground clearance. The results of this research work show new proposed design of the WIG craft with compound wing and endplates, which can clearly increase the aerodynamic efficiency without compromising the longitudinal stability. The use of WIG craft is representing an ambitious technology that will help in reducing time, effort, and money of the conventional marine transportation in the future.

/pdf/experimental-investigation-of-a-wing-in-ground-effect-craft-lnzcommh5t.pdf

Experimental investigation of a wing-in-ground effect craft.

Flow structure is a crucial point for the conceptual design of Wing-in-Ground effect (WIG) crafts. In this study, pressure distributions around a compound wing, velocity and the turbulent intensity distribution in the wake area after trailing of the wing, have been investigated numerically. Computational simulations were completed regarding various angles of attack in-ground-effect. Two parts made up the compound wing: The first composed by one rectangular wing in the center, the second composed by a reverse taper wing, consisting of an anhedral angle at the side. A realizable k-e turbulent model exhibited the flow field in the physical domain about the wing surface. The numerical results of the compound wing were validated using the data provided by wind tunnel tests. The flow structures around the compound wing were compared with that of a rectangular wing for different conditions. It was found that the pressure distribution on the rectangular wing was weaker than at the lower surface for the compound wing. However, the suction effect on the upper surface of the rectangular wing was higher. Also, the velocity defect and the turbulence level in the wake area was greater behind the compound wing.

https://www.mdpi.com/2077-1312/8/3/156/pdf

Saeed Jamei

Papers

Numerical simulation of vertical water impact of asymmetric wedges by using a finite volume method combined with a volume-of-fluid technique

Numerical Investigation on Aerodynamic Characteristics of a Compound Wing-in-Ground Effect

Experimental investigation of a wing-in-ground effect craft.

Wake behind a Compound Wing in Ground Effect

Ground boundary layers effect on aerodynamic coefficients of a compound wing with respect to design parameters