• Title/Summary/Keyword: Virtual Wind Tunnel

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Wind Tunnel Test of MRP Model using External Balance

  • Chung, Jindeog;Sung, Bongzoo;Cho, Taehwan
    • International Journal of Aeronautical and Space Sciences
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    • v.1 no.2
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    • pp.68-74
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    • 2000
  • A comparative wind tunnel testing of an airplane model was performed at the Korea Aerospace Research Institute Low Speed Wind tunnel(KARI LSWT). The model used for the comparative test was a seaplane model from the Glenn L. Martin Wind(GLM) Tunnel of University of Maryland, U.S.A. The 6-component external balance used in force and moment measurement is pyramidal type, which is a precision device that has strain gauge-type load cell inside of balance and the virtual center of the balance coincides with the tunnel centerline. Image method is adopted to eliminate the tare and interference of the model support, and to correct the flow angularity to the model also. Test results from KARI LSWT were compared with the results from GLM tunnel.

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The numerical wind tunnel for industrial aerodynamics: Real or virtual in the new millennium?

  • Stathopoulos, T.
    • Wind and Structures
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    • v.5 no.2_3_4
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    • pp.193-208
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    • 2002
  • Previous studies have shown that Computational Wind Engineering (CWE) is still in its infancy and has a long way to go to become truly useful to the design practitioner. The present work focuses on more recent studies to identify progress on outstanding issues and improvements in the numerical simulation of wind effects on buildings. The paper reviews wind loading and environmental effects; it finds that, in spite of some interesting and visually impressive results produced with CWE, the numerical wind tunnel is still virtual rather than real and many more parallel studies - numerical and experimental - will be required to increase the level of confidence in the computational results.

BARAM: VIRTUAL WIND-TUNNEL SYSTEM FOR CFD SIMULATION (BARAM: 전산유체 해석을 위한 가상풍동 시스템)

  • Kim, Min Ah;Lee, Joong-Youn;Gu, Gibeom;Her, Young-Ju;Lee, Sehoon;Park, Soo Hyung;Kim, Kyu Hong;Cho, Kumwon
    • Journal of computational fluids engineering
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    • v.20 no.4
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    • pp.28-35
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    • 2015
  • BARAM system that means 'wind' in Korean has been established as a virtual wind tunnel system for aircraft design. Its aim is to provide researchers with easy-to-use, production-level environment for all stages of CFD simulation. To cope with this goal an integrated environment with a set of CFD solvers is developed and coupled with an highly-efficient visualization software. BARAM has three improvements comparing with previous CFD simulation environments. First, it provides a new automatic mesh generation method for structured and unstructured grid. Second, it also provides real-time visualization for massive CFD data set. Third, it includes more high-fidelity CFD solvers than commercial solvers.

Numerical evaluation of the effect of multiple roughness changes

  • Abdi, Daniel S.;Bitsuamlak, Girma T.
    • Wind and Structures
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    • v.19 no.6
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    • pp.585-601
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    • 2014
  • The effect of multiple roughness changes close to a building site was examined through three dimensional computational fluid dynamics (CFD) simulations conducted in a virtual boundary layer wind tunnel (V-BLWT). The results obtained were compared with existing wind speed models, namely ESDU-82026 and Wang and Stathopoulos (WS) model. The latter was verified by wind tunnel tests of sixty nine cases of multiple roughness patches, and also with a simplified 2D numerical model. This work extends that numerical study to three dimensions and also models roughness elements explicitly. The current numerical study shows better agreement with the WS model, that has shown better agreements with BLWT tests, than the ESDU model. This is in contrast to previous results of Wang and Stathopoulos, who concluded that CFD shows better agreement with the ESDU model. Many cases were simulated in a V-BLWT that has same dimensions as BLWT used in the original experiment and also in a reduced symmetrical version (S-BLWT) that takes advantage of regular arrangement of roughness blocks. The S-BLWT gives results almost identical to V-BLWT simulations, while achieving significant reduction on computational time and resources.

A Study on the Methyl Salicylate Dispersion in the Vicinity of Obstacles by Wind Tunnel Test (아음속 풍동을 이용한 구조물 형상 변화에 따른 살리실산메틸 확산 유동 연구)

  • Hong, Chang-Ki;Uhm, Han-Sup;Choi, Seung-Ki;Kim, Youn-Jea
    • The KSFM Journal of Fluid Machinery
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    • v.17 no.6
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    • pp.69-73
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    • 2014
  • To predict flow fields and chemical agent dispersion in urban area, wind tunnel experiments was performed. The agent was adopted MS (methyl salicylate) because the real chemical agent is unsafe. The exact concentration of methyl salicylate was generated by the commercial gas generator (STI-2500) and three different obstacle shapes were applied (i.e., rectangular, cylinder and pyramid). The concentration was measured with the qualified ion mobility sensor and gas chromatography. The data necessary for virtual test method of the real chemical agent were obtained.

CORRELATION BETWEEN THE OPENING ANGLE OF A LOUVER AND FLOW RATE FOR THE EFFICIENT CONTROL OF A LARGE FAN (대형 팬의 효율적 유량 조절을 위한 루버 개폐각 상관관계)

  • Noh, T.H.;Lee, S.J.;Chang, S.M.
    • 한국전산유체공학회:학술대회논문집
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    • 2007.10a
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    • pp.272-276
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    • 2007
  • In this paper, we researched a parametric study in flow control system using louver with numerical method. Generally, for the large fans with constant rotational speed, the louver can be used to control the flow rate. The opening and closing of louver can make a some change of flow properties generated by a large fan. To develope the relation between the opening angle of louver and flow rate(or pressure difference), we simulated the flow past the modelled louver installed in a virtual wind tunnel. For the various angles, the mean flow properties are investigated and parameterized with a given boundary condition. The research result can be used directly to design the flow control system of large constant-speed fans, which are often applied to petrolic refinery system.

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A Study on the Pollutant Dispersion over a Mountain Valley Region (II) : Numerical Simulation (산악 계곡지형에서의 오염확산에 관한 연구(II) :수치해석)

  • Shim Woo-Sup;Kim Seogcheol;Yoo Seong-Yeon
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.17 no.11
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    • pp.1060-1071
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    • 2005
  • Passive gas dispersions over a 1/1000 scale terrain model at Eiffel type wind tunnel were reproduced by numerical simulation. Large eddy simulation was used to treat the sub-grid scale turbulences. The terrain features were represented by millions of point forces densely distributed over the solid surface using the virtual boundary method. The model simulations agreed very well with the experiments in a consistent fashion for all wind directions. The measured profiles of the wind speeds as well as the tracer gas concentrations were nicely simulated by the CFD model at most locations scattered over the model terrain. With scale factor adjusted and the thermal stratification effects incorporated, the CFD model was expected to provide reliable information on pollutant dispersions over the real complex terrains.

Virtual Flutter Test of a Spanwise Curved Wing Using CFD/CSD Integrated Coupling Method (CFD/CSD 통합 연계기법을 이용한 횡방향 곡률이 있는 날개의 가상 플러터 시험)

  • Oh, Se-Won;Lee, Jung-Jin;Kim, Dong-Hyun
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.16 no.4 s.109
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    • pp.355-365
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    • 2006
  • The coupled time-integration method with a staggered algorithm based on computational structural dynamics (CSD), finite element method (FEM) and computational fluid dynamics (CFD) has been developed in order to demonstrate physical vibration phenomena due to dynamic aeroelastic excitations. Virtual flutter tests for the spanwise curved ing model have been effectively conducted using the present advanced computational method with high speed parallel processing technique. In addition, the present system can simultaneously give a recorded data file to generate virtual animation for the flutter safety test. The results for virtual flutter test are compared with the experimental data of wind tunnel test. It is shown from the results that the effect of spanwise curvature have a tendency to decrease the flutter dynamic pressure for the same flight condition.

Virtual Flutter Test of Spanwise Curved Wings Using CFD/CSD Coupled Dynamic Method (CFD/CSD 정밀 연계해석기법을 이용한 3차원 곡면날개의 가상 플러터 시험)

  • Kim, Dong-Hyun;Oh, Se-Won;Kim, Hyun-Jung
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2005.11a
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    • pp.457-464
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    • 2005
  • The coupled time-integration method with a staggered algorithm based on computational structural dynamics (CSD), finite element method (FEM) and computational fluid dynamics (CFD) has been developed in order to demonstrate physical vibration phenomena due to dynamic aeroelastic excitations. Virtual flutter tests for the spanwise curved wing model have been effectively conducted using the present advanced computational methods with high speed parallel processing technique. In addition, the present system can simultaneously give a recorded data fie to generate virtual animation for the flutter safety test. The results for virtual flutter test are compared with the experimental data of wind tunnel test. It is shown from the results that the effect of spanwise curvature have a tendency to decrease the flutter dynamic pressure for the same flight condition.

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Turbulent Dispersion Behavior of a Jet Issued into Thermally Stratified Cross Flows(I) (열적으로 성층화된 횡단류에 분출된 제트의 난류확산 거동(I))

  • Kim, Kyung Chun;Kim, Sang Ki
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.23 no.2
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    • pp.218-225
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    • 1999
  • Flow visualization study has been conducted to simulate the turbulent dispersion behavior of a crossflow jet physically under the conditions of various thermal stratification in a wind tunnel. A smoke jet with the constant ratio of the jet to freestream velocity is injected normally to the cross flow of the thermally stratified wind tunnel(TSWT) for flow visualization. The typical natures of the smoke dispersion under different thermal stratifications such as neutral, weakly stable, strongly stable, weakly unstable, strongly unstable and inversion layer are successfully reproduced in the TSWT. The Instantaneous velocity and temperature fluctuations are measured by using a cold and hot-wire combination probe. The time averaged dispersion behaviors, the centerline trajectories, the spreading angles and the virtual origins of the cross jet are deduced from the edge detected images with respect to the stability parameter. All the general characteristics of the turbulent dispersion behavior reveal that the definitely different dispersion mechanisms are inherent in both stable and unstable conditions. It is conjectured that the turbulent statistics obtained in the various stability conditions quantitatively demonstrate the vertical scalar flux plays a key role in the turbulent dispersion behavior.