• Journal of the Korean Society of Propulsion Engineers
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• v.12 no.1
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• pp.7-15
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• 2008

Pressure Sensitive Paint(PSP) means a reacting paint in pressure. The calibration of PSP and the wind tunnel test of PSP painted model are required to measure pressure by using PSP. Therefore, the post processing from these results shows the information and image of the pressure distribution. PSP can show the information of total pressure from the wind tunnel test and the calibration. In this study, equipments of PSP are composed, and experiment is accomplished by using PSP. The surface pressure distribution around the wall of nozzle is measured by PSP. The measured pressure has similar results to those of the CFD and pressure tap measurement.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.04a
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• pp.391-394
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• 2011

In this paper, the shock angle and effect had been compared with numerical data within supersonic area at an forebody such as missiles or an aircraft. By using supersonic wind tunnel in Seoul National University, The shock position and magnitude were measured in the model of cone shape according to mach number. The experiment had been conducted at mach number 2.0, 3.0, and 3.8. As a result, the shock position and magnitude are different from flow velocity, AOA, and AOS in some cases blockage effect had occurred.

• Wind and Structures
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• v.12 no.4
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• pp.299-312
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• 2009

It has long been studied about the flow around bluff bodies, but the effect of aspect ratio on the sharp-edged bodies in thick turbulent boundary layers is still argued. The author investigates the flow characteristics around a series of rectangular bodies ($40^d{\times}80^w{\times}80^h$, $80^d{\times}80^w{\times}80^h$ and $160^d{\times}80^w{\times}80^h$ in mm) placed in a deep turbulent boundary layer. The study is aiming to identify the extant Reynolds number independence of the rectangular bodies and furthermore understand the surface pressure distribution around the bodies such as the suction pressure in the leading edge, when the shape of bodies is changed, responsible for producing extreme suction pressures around the bluff bodies. The experiments are carried out at three different Reynolds numbers, based on the velocity U at the body height h, of 24,000, 46,000 and 67,000, and large enough that the mean boundary layer flow is effectively Reynolds number independent. The experiment includes wind tunnel work with the velocity and surface pressure measurements. The results show that the generation of the deep turbulent boundary layer in the wind tunnel and the surface pressure around the bodies were all independent of Reynolds number and the longitudinal length, but highly dependent of the transverse width.

• 한국전산유체공학회:학술대회논문집
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• 2008.03b
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• pp.212-215
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• 2008

e-AIRS, an abbreviation of 'e-Science Aerospace Integrated Research System,' is a virtual organization supporting CFD(computational fluid dynamics) simulations, remote experimental service, and collaborative and integrative study between computation and experiment. e-AIRS works on the e-Science environment and research process is accomplished through the web portal. By the system development since 2005, a stable education system with the full support on fluid dynamics is successfully established and utilized to various fluid dynamic lectures in universities. By using e-AIRS system during a lecture, students can conduct the full CFD simulation process on the web and inspect the wind tunnel experiment via Access Grid. This kind of interactive lecture makes students to have a deeper understanding on the physics of fluid, as well as the characteristics of numerical techniques. The current paper will describe system components of e-AIRS and its utilization on education.

• Wind and Structures
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• v.25 no.1
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• pp.1-24
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• 2017

This paper presents a 1:25 multi-freedom aero-elastic model for a high lighting pole at the Zhoushan stadium. To validate the similarity characteristics of the model, a free vibration test was performed before the formal test. Beat phenomenon was found and eliminated by synthesis of vibration in the X and Y directions, and the damping ratio of the model was identified by the free decay method. The dynamic characteristics of the model were examined and compared with the real structure; the similarity results were favorable. From the test results, the major along-wind dynamic response was the first vibration component. The along-wind wind vibration coefficient was calculated by the China code and Eurocode. When the peak factor equaled 3.5, the coefficient calculated by the China code was close to the experimental result while Eurocode had a slight overestimation of the coefficient. The wind vibration coefficient during typhoon flow was analyzed, and a magnification factor was suggested in typhoon-prone areas. By analyzing the power spectrum of the dynamic cross-wind base shear force, it was found that a second-order vortex-excited resonance existed. The cross-wind response in the test was smaller than Eurocode estimation. The aerodynamic damping ratio was calculated by random decrement technique and the results showed that aerodynamic damping ratios were mostly positive at the design wind speed, which means that the wind-induced galloping phenomenon is predicted not to occur at design wind speeds.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.43 no.5
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• pp.422-431
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• 2015

Wind tunnel testing to construct static aerodynamic database of KF-16 was conducted for preceding research of design of experiments in wind tunnel testing. The test model is KF-16 scaled 1/33 and it has horizontal tail, flaperon, and rudder. The experiments consist of one experiment for analyzing aerodynamic coefficients under whether or not horizontal tail is present and four experiments for analyzing aerodynamic coefficients of changes of deflection angle in control surface which are flap, flaperon, rudder, and horizontal tail. After conducting wind tunnel testing, the experimental results show that the control surface changes have a great effect on Aerodynamic characteristics.

• Asian Journal of Atmospheric Environment
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• v.2 no.1
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• pp.1-13
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• 2008

A numerical simulation method has been developed to predict atmospheric flow and stack gas diffusion using a calculation domain of several km around a stack under complex terrain conditions containing buildings. The turbulence closure technique using a modified k-$\varepsilon$-type model under a non hydrostatic assumption was used for the flow calculation, and some of the calculation grids near the ground were treated as buildings using a terrain-following coordinate system. Stack gas diffusion was predicted using the Lagrangian particle model, that is, the stack gas was represented by the trajectories of released particles. The numerical model was applied separately to the flow and stack gas diffusion around a cubical building and to a two-dimensional ridge in this study, before being applied to an actual terrain containing buildings in our next study. The calculated flow and stack gas diffusion results were compared with those obtained by wind tunnel experiments, and the features of flow and stack gas diffusion, such as the increase in turbulent kinetic energy and the plume spreads of the stack gas behind the building and ridge, were reproduced by both calculations and wind tunnel experiments. Furthermore, the calculated profiles of the mean velocity, turbulent kinetic energy and concentration of the stack gas around the cubical building and the ridge showed good agreement with those of wind tunnel experiments.

• International Journal of High-Rise Buildings
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• v.11 no.3
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• pp.145-156
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• 2022

Application examples of computational fluid dynamics (CFD) in the planning stage of high-rise buildings are introduced. First, we introduce examples of applications in the environmental field. The pedestrian wind environment was one of the earliest practical examples of CFD. CFD was also employed to validate the heat island mitigation measures proposed as part of the new construction plan. Second, application examples of wind-force evaluations are introduced. Prediction examples are presented for the peak wind pressure around a complex-shaped building and the wind force evaluation for a base-isolated building. The results prove that the results of the proper execution of CFD are equivalent to those of the wind tunnel experiment. As examples of CFD applications of other issues related to high-rise building planning, we introduce snow accretion on outer walls and high-temperature exhaust from emergency generators. Finally, the future prospects for the use of CFD are discussed.

• Wind and Structures
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• v.2 no.3
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• pp.173-187
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• 1999

The flow around a structure has been an important subject in wind engineering research. There are various kinds of unstable aerodynamic phenomena with regard to a bluff body. In order to understand the physical mechanism of aerodynamic and aeroelastic instability of a bluff body, the relations between the flow around structures and the motion of body with various section shapes should be investigated. Based on a series of wind tunnel tests, this paper addresses the aerodynamic stability of square cylinder with various corner cuts and attack angles in the uniform flow. The test results show that the models with corner cut produced generally better behaviour for the galloping phenomenon than the original section. However, the corner cut method can not prevent the occurrence of the vortex-induced vibration(VIV). It is also shown that as the attack angle changes, the optimum size of corner cut changes also. This means that any one specific size of corner cut which shows the best aerodynamic behaviour throughout all the cases of attack angles does not exist. This paper presents an intensive study on obtaining the optimum size of corner cut for the stabilization of aerodynamic behaviour of cylinders.

• Proceedings of the KSME Conference
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• 2007.05b
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• pp.2923-2928
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• 2007

The study of model for velocity and turbulence within the urban canopy was carried out. To evaluate existing urban model we conducted wind tunnel experiment and large-eddy simulation (LES). Mean velocity profile and turbulence are measured within simple three different obstacle arrays. To obtain supplemental data and to verify morphological model large-eddy simulation was performed. Several methods have been used to achieve embodying the flow field in urban area. Recently, morphological method obtaining flow parameters from the statistical or physical representation of obstacle elements is a arising method. It was found that all morphological model, evaluated in this study, over predict the friction velocity, most sensitive one among the flow parameters. Velocity and turbulence in the urban canopy layer were improved by the correction using 'true' friction velocity.