• Proceedings of the KSR Conference
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• 2011.10a
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• pp.1320-1326
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• 2011

The maximum speed of high-speed rail is restricted to various factors such as track condition including slope and radius, tunnel and dynamic stability of vehicle. Among the various factors, traction effort and resistance to motion is principal and basic factor. In addition, at high speed over 300km/h, aerodynamic drag amounts up to 80% of resistance to motion, that it can be said that aerodynamic drag is the most important factor to decide the maximum speed of high-speed rail system. This paper deals with a measure to increase the maximum speed of high-speed train by reducing aerodynamic drag. The traction effort curve and resistance to motion curve of existing high-speed train under development has been employed to set up the target of aerodynamic drag reduction to reach up to 500km/h without modification traction system. In addition, the contribution of various sources of aerodynamic drag to total value has been analyzed and the strategy for implementation of aerodynamic drag reduction has been discussed based on the aerodynamic simulation results around the train using computational fluid dynamics.

• Journal of the Korean Society for Railway
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• v.19 no.6
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• pp.709-716
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• 2016

To reduce the aerodynamic drag of high speed trains, aerodynamic drag of KTX-Sancheon was analyzed in detail according to individual components. Aerodynamic drag values of the power cars (front car, rear car) and bogies are about 42.9% and 10.1% of the total aerodynamic drag, respectively. For the aerodynamic drag reduction of a power-car, a nose shape optimization was conducted using the Broyden-Fletcher-Goldfarb-Shanno optimum method. Shape change of a power car and bogie fairing adaptation are used to reduce the aerodynamic drag of a car body. The aerodynamic drag of the optimized train-set dropped by 15.0% compared to the aerodynamic drag of the KTX-Sancheon; a running resistance reduction of 12% is expected at the speed of 350km/h.

• Wind and Structures
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• v.12 no.4
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• pp.285-298
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• 2009

For long-span suspension bridges with their intrinsic limit in flutter, some counter measures, for example, central stabilizers, should be adopted to improve aerodynamic stability to meet with the appropriate wind resistance requirements. The present paper introduces aerodynamic stabilization for long-span suspension bridges with box girders by using central stabilizers based on Xihoumen Bridge with the main span of 1650 m. The aerodynamic stabilization study covers experimental investigation of sectional model testing, comprehensive evaluation of three central stabilizers and theoretical analysis of stabilizing mechanism related to flutter derivatives, aerodynamic damping and degree participation.

• Journal of computational fluids engineering
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• v.19 no.1
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• pp.41-46
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• 2014

The aerodynamic drag of high-speed train has been calculated and the effect of bogie side fairing on the aerodynamic drag has been investigated. Computational Fluid Dynamics (CFD) simulation based on steady-state 3 dimensional Navier-Stokes equation has been conducted employing FLUENT 12 and the aerodynamic model of HEMU-430x, the Korean next generation high-speed train under development has been built using GAMBIT 2.4.6. Three types of bogie side fairing configuration, the proto-type without fairing, half-covered fairing to avoid the interference with the bogie frame and full-covered fairing have been adopted to the train model to compare the drag reduction effects of the bogie side fairing configurations and the numerical results yields that the bogie side fairing can reduce the aerodynamic drag of the 6-car trainset up to 7.8%. The aerodynamic drag coefficient of each vehicle as well as the flow structures around the bogie system have also been examined to analyze the reason and mechanism of the drag reduction by bogie side fairing.

• Transactions of the Korean Society of Automotive Engineers
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• v.14 no.2
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• pp.194-201
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• 2006

Roof-fairing and deflector system have been used on heavy-duty trucks to minimize aerodynamic drag force not only for driving stability of the truck but also for energy saving by reducing the required driving power of the vehicle. In this study, a numerical simulation was carried out to see aerodynamic effect of the drag reducing device on the model vehicle. Drag and lift force generated on the five different models of the drag reducing system were calculated and compared them each other to see which type of device is efficient on the reduction of driving power of the vehicles quantitatively. An experiment has been done to see airflow characteristics on the model vehicles. Airflow patterns around the model vehicles were visualized by smoke generation method to compare the complexity of airflow around drag reducing device. From the results, the deflector systems(Model 5,6) were revealed as a better device for reduction of aerodynamic drag than the roof-fairing systems(Model 2,3,4) on the heavy-duty truck and it can be expected that over 10% of brake power of an engine can be saved on a tractor-trailer by the aerodynamic drag reducing device at normal speed range($80km/h{\sim}$).

• Journal of the Korean Society for Railway
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• v.16 no.3
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• pp.169-174
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• 2013

The effect of modifying the shape of a high-performance EMU train on the aerodynamic drag is studied here using Computational Fluid Dynamics(CFD) based on three dimensional Steady-state Navier-Stokes equation and two equation turbulence modeling. FLUENT 12 and Gambit 2.4.6 are employed for a numerical simulation of the aerodynamic drag of a streamlined-shape train as well as a proto type train. The characteristics of the aerodynamic drag of trains in tunnels are analyzed in a comparison with these characteristics in an open space. The contribution of the aerodynamic drag of each case is also investigated to establish principal pertaining to drag reduction for urban trains in tunnels. The aerodynamic drag of a streamlined train was reduced to 9.8% relative to a proto-type train with a blunt nose and a protruding roof facility and underbody shape: the running resistance is expected to be reduced by as much as 4% at a running speed of 80km/h.

• Journal of Climate Change Research
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• v.7 no.2
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• pp.177-184
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• 2016

Recently, the need for technology development of commercial vehicle fuel consumption has emerged. Fuel economy improvement of transport equipment and transportation efficiency, and increasing attention to the logistics cost reduction measures. Increasing attention to the logistics cost reduction measures by fuel economy improvement of transport equipment and transportation efficiency. In this study, we have installed aerodynamic reduction device (side skirt, boat tail) to 14.5 ton cargo trucks and 45 ft tractor-trailers. And the fuel consumption was compared installed before and after. Fuel economy assessment for the aerodynamic reduction value device was tested by modifying the SAE J1321 Joint TMC/SAE Fuel Consumption Test Procedure - Type II test in according domestic situation. Greenhouse gas reductions were calculated in accordance with the scenario, including fuel consumption test results. When the 14.5 ton cargo trucks has been equipped with side skirts and boat tail, it confirmed the improvement in fuel efficiency of 4.72%. One Heavy-duty truck's the annual greenhouse gas reductions value are $6.86ton\;CO_2\;eq$. And if applying the technology to more than 50% of registered 15 ton trucks, greenhouse gas reductions are calculated as $686,826ton\;CO_2\;eq./yr$.

• Wind and Structures
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• v.31 no.1
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• pp.15-20
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• 2020

The aircraft industry supports aviation by building aircraft and manufacturing aircraft parts for their maintenance. Fuel economization is one of the biggest concerns in the aircraft industry. The reduction in specific fuel consumption of aircraft can be achieved by a variety of means, simplest and more effective is the one to impose minor modifications in the aircraft main wing or the parts which are exposed to the air flow. This method can lead to a reduction in aerodynamic resistance offered by the air and have a smoother flight. The main objective of this study is to propose geometric design modifications on an existing aircraft wing which acts as a vortex generator and it can reduce the drag and increase lift to drag ratio, leading to lower fuel consumption. The NACA 2412 aircraft wing is modified and designed. Rigorous flow analysis is carried out using computational fluid dynamics based software Ansys Fluent. Results show that saw tooth modification to the main wing shows the best aerodynamic efficiency as compared to other modifications.

• Journal of Aerospace System Engineering
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• v.16 no.2
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• pp.25-32
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• 2022

A cab roof fairing is a device that reduces the drag coefficient of a commercial vehicle, by controlling the resistance of flow separation occurring in the front when the commercial vehicle travels. Commercial vehicles are designed to facilitate aerodynamic resistance that cannot be avoided from the driving direction of the vehicle, because they must structurally load containers in the rear. For this reason, it is closely related to oil costs and environmental pollutants. In this study, the 3D fairing shape was designed based on the Rankine half body theory, and the design results were verified through aerodynamic analysis.

• International Journal of Automotive Technology
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• v.6 no.3
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• pp.221-227
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• 2005

Aim of this study is to investigate an aerodynamic effect of a drag-reducing device on a heavy-duty truck. The vehicle experiences two different kinds of aerodynamic forces such as drag and uplifting force (or downward force) as it is traveling straight forward at constant speed. The drag force on a vehicle may cause an increase of the rate of fuel consumption and driving instability. The rolling resistance of the vehicle may be increased as result of the negative uplifting or downward force on the vehicle. A device named roof-fairing system has been applied to examine the reduction of aerodynamic drag force on a heavy-duty truck. As for a engineering design information, the drag-reducing system should be studied theoretically and experimentally for the best efficiency of the device. Four different types of roof-fairing model were considered in this study to investigate the aerodynamic effect on a model truck. The drag and downward force generated by vehicle has been obtained from numerical calculation conducted in this study. The forces produced on four fairing models considered in this study has been compared each other to evaluate the best fairing model in terms of aerodynamic performance. The result shows that the roof-fairing mounted truck has bigger negative uplifting or downward force than that of non-mounted truck in all speed ranges, and drag force on roof-fairing mounted truck has smaller than that of non-mounted truck. The drag coefficient $(C_D)$ of the roof-fairing mounted truck (Model-3) is reduced up to $41.3\%$ than that of non-mounted trucks (Model-1). A downward force generated by a roof-fairing mounted on a truck is linearly proportional to the rolling resistance force. Therefore, the negative lifting force on a heavy-duty truck is another important factor in aerodynamic design parameter and should be considered in the design of a drag-reducing device of a tractor-trailer. According to the numerical result obtained from present study, the drag force produced by the model-3 has the smallest of all in all speed ranges and has reasonable downward force. The smaller drag force on model-3 with 2/3h in height may results of smallest thickness of boundary layer generated on the topside of the container and the lowest intensity of turbulent kinetic energy occurs at the rear side of the container.