• 한국전산유체공학회:학술대회논문집
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• 2006.05a
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• pp.90-93
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• 2006

• International Journal of Aeronautical and Space Sciences
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• v.17 no.1
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• pp.1-7
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• 2016

The influence of boundary condition of the bodies with gas flows is one of the most important problems in high-altitude aerodynamics. In this paper presents the results of the calculation of aerodynamic characteristics of aerospace vehicle using Monte-Carlo method based on three different gas-surface interaction models - Maxwell model, Cercignani-Lampis-Lord (CLL) model and Lennard-Jones (LJ) potential. These models are very sensitive for force and moment coefficients of aerospace vehicle in the hypersonic free molecular flow. The models, method and results can be used for new generation aerospace vehicle design.

• Bulletin of the Korean Space Science Society
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• 2004.10b
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• pp.258-261
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• 2004

Numerical simulations are made to predict the axial force coefficients of a two-stage launch vehicle, and the results are compared with those by wind tunnel tests. It is found that the forebody axial force is not affected by whether the base of the body is modeled or not. Modeling the sting support used in wind tunnel tests reduced the base axial force compared to the results without it. The present calculation shows that the forebody axial forces are underestimated while the base axial forces are overestimated. The total axial force, therefore, compares with the experimental data with better accuracy by cancelling out the errors of opposite signs. Modeling of the sting support in numerical simulations is found to be necessary to get a better agreement with the experiments for both base and overall axial force coefficients.

• Bulletin of the Korean Space Science Society
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• 2004.10b
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• pp.239-242
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• 2004

The fairing of the launch vehicles has a role of protecting the spacecraft from outer thermal, acoustical, and mechanical loads during flight. Among them, the thermal load is analyzed in the present study. The ascent thermal analyses include aerodynamic heating rate on every point of the fairing, heat transfer through the fairing and spacecraft, and the final temperature during ascent flight phase. A design code based on theoretical/experimental database is applied to calculate the aerodynamic heating rate, and a thermal math program, SINDA/Fluint, is considered for conductive heat transfer of the fairing. The results show that the present design satisfies the allowing temperature of the structure. Another important thermal problem, pyro explosive fairing separation device, is calculated because the pyro system is very sensitive to the temperature. The results also satisfies the pyro thermal condition.

• Wind and Structures
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• v.20 no.2
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• pp.117-142
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• 2015

The performance of bridges under strong wind and traffic is of great importance to set the traveling speed limit or to make operational decisions for severe weather, such as controlling traffic or even closing the bridge. Meanwhile, the vehicle's safety is highly concerned when it is running on bridges or highways under strong wind. During the past two decades, researchers have made significant contributions to the simulation of the wind-vehicle-bridge system and their interactive effects. This paper aims to provide a comprehensive review of the overall performance of the bridge and traffic system under strong wind, including bridge structures and vehicles, and the associated mitigation efforts.

• Journal of Aerospace System Engineering
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• v.4 no.2
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• pp.10-15
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• 2010

Aerodynamic noise is becoming the major source of annoyance for modern cars recently and is caused by many different noise sources in a car. Appropriate CFD technologies, therefore, have been developed to resolve the noise problems related with aerodynamics. It is necessary for designers to fully understand the relationship between vehicle aerodynamics and wind noise acoustics. In this study, we simulate the flow fields around two different shapes of side mirror models of passenger car and analyze the noise phenomena around one side mirror model that has lower drag than the other model using Fluent 6.3.

• Journal of Institute of Convergence Technology
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• v.7 no.1
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• pp.23-29
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• 2017

A pterosarus is an ancient flying reptile and the first vertebrate with powered flight. The shapes of the pretosarus'airfoil in the published literature are reconstructed. The aerodynamics of the Pterosarus is obtained using a free software XFOIL. The steady aerodynamics of the Pterosarus' airfoil are investigated focusing on the gliding performance. The numerical results are validated by comparing the computed aerodynamic coefficients with the measured data. The secretes of the Pterosarus' highly camberred airfoil are elucidated by comparing the aerodynamics with that of the birds'.

• Journal of Aerospace System Engineering
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• v.3 no.4
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• pp.1-6
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• 2009

Aerodynamic noise is becoming the major source of annoyance for modern cars recently and is caused by many different noise sources in a car. Appropriate CFD technologies, therefore, have been developed to resolve the noise problems related with aerodynamics. It is necessary for designers to fully understand the relationship between vehicle aerodynamics and wind noise acoustics. In this study, we simulate the flow fields around two different shapes of side mirror models of passenger car and analyze the noise phenomena around one side mirror model that has lower drag than the other model using Fluent 6.3.

• Wind and Structures
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• v.11 no.4
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• pp.257-273
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• 2008

A number of passive aerodynamic drag reduction methods were applied separately and then in different combinations on an intercity bus model, through wind tunnel studies on a 1:20 scale model of a Mercedes Benz Tourismo 15 RHD intercity bus. Computational fluid dynamics (CFD) modelling was also conducted in parallel to assist with flow visualisation. The commercial CFD package $CFX^{TM}$ was used. It has been found that dramatic reductions in coefficient of drag ($C_D$) of up to 70% can be achieved on the model using tapered and rounded top and side leading edges, and a truncated rear boat-tail. The curved front section allows the airflow to adhere to the bus surfaces for the full length of the vehicle, while the boat-tails reduce the size of the low pressure region at the base of the bus and more importantly, additional pressure recovery occurs and the base pressures rise, reducing drag. It is found that the CFD results show remarkable agreement with experimental results, both in the magnitude of the force coefficients as well as in their trends. An analysis shows that such a reduction in aerodynamic drag could lead to a significant 28% reduction in fuel consumption for a typical bus on intercity or interstate operation. This could translate to a massive dollar savings as well as significant emissions reductions across a fleet. On road tests are recommended.

• Proceedings of the KSME Conference
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• 2003.04a
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• pp.1724-1729
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• 2003

A new ground transportation system is often simulated by the wing in ground effect(WIG). Recently, several kinds of experimental and computational studies are being carried out to investigate the WIG aerodynamic characteristics which are of practical importance to develop the new ground transportation vehicle system. These works are mainly based on conventional wind tunnel tests, but many problems associated with the WIG aerodynamic characteristics can not be satisfactorily resolved. In order to develop the new ground transportation vehicle system the WIG should be further investigated. To do this, it is necessary to develop a s imulator appropriate to the WIG aerodynamics. The objective of the present study is to clarify the aerodynamic characteristics of the WIG and to develop a new experimental test rig for the investigation of the WIG aerodynamics. Some preliminary experiments are performed to investigate the usefulness of the WIG simulator.