• 제목/요약/키워드: Low Speed Wind Tunnel

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저속 풍동시험 시 NASA Common Research Model의 Belly Sting 모형 지지부에 의한 간섭효과에 관한 연구 (Belly Sting Model Support Interference Effect of NASA Common Research Model at Low Speed Wind Tunnel)

  • 차경환;김남균;고성호
    • 한국항공우주학회지
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    • 제49권3호
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    • pp.167-174
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    • 2021
  • NASA Common Research Model의 29.7% 축소 모형에 대하여 저속 풍동시험 조건으로 수치해석을 수행하였다. 낮은 레이놀즈수 영역인 0.3×106에서 Belly sting 모형 지지부를 장착한 CRM의 공력계수를 측정하는 시험이 수행되었으며, 수치해석 결과와 비교하였다. 해석의 타당성을 검증하기 위해 선행연구 조건으로 전산해석을 수행하여 비교하였다. Belly sting 모형 지지부 유무에 대한 해석 결과 지지부에 의한 간섭 효과로 동체뿐만 아니라 주날개, 꼬리날개까지 공력에 영향이 있음을 확인하였다.

시간영역 빔포밍을 사용한 풍력터빈 축소모델 소음원 측정 (Acoustic Noise Measurement for the Wind Turbine Blade by Using Time-domain Beamforming)

  • 조태환;김철완
    • 신재생에너지
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    • 제5권2호
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    • pp.25-30
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    • 2009
  • The wind tunnel test to identify the acoustic noise source position of the wind turbine blade was conducted in KARI low speed wind tunnel. Microphone array and time-domain beamforming methodology was applied to this study. To reduce the data processing time, a modified beamforming method with a criteria between calculation time step and grid size for rotating angle in the cylinderical coordinate system was proposed. The test results shows that the data processing time to identify the noise source position was reduced to 20% compared with conventional method. And the dominant noise source of the blade moves from inboard to blade tip as the frequency increases.

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중형 전기추진 무인기용 프로펠러 풍동시험 (Wind Tunnel Test on Propellers for Middle Size Electric Propulsion UAV)

  • 박부민;황오식;김영문;김춘택;권기정
    • 한국추진공학회:학술대회논문집
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    • 한국추진공학회 2011년도 제37회 추계학술대회논문집
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    • pp.784-788
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    • 2011
  • 한국항공우주연구원(KARI)에서 개발 중인 중형 전기추진 무인기에 사용할 프로펠러의 선정을 위하여 프로펠러의 비행조건 성능을 풍동시험을 통하여 측정하였고, 해석으로부터 예측된 성능과 비교하였다. 시험은 KARI의 대형 아음속 풍동에서 수행되었다. 시험에 사용된 프로펠러들은 지름 21" 폴딩 타입 상용 제품이다. 시험 결과로부터, 순항조건에서 66%의 효율을 보인 21"${\times}$15.5" 프로펠러가 선정되었다.

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한국형 고속전철용 판토그라프의 설계 및 제작 (The Design and Manufacture of Pantograph for Korean High Speed Train)

  • 김휘준;박수홍;정경렬;배정찬
    • 한국소음진동공학회:학술대회논문집
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    • 한국소음진동공학회 2001년도 추계학술대회논문집 II
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    • pp.1223-1228
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    • 2001
  • We have been developing the pantograph for Korean High Speed Train for the last five years. To fulfil the following requirements at designed speed of 350km/h : 1) contact loss less than 1 %, 2) aerodynamic noise less than 91dB, 3) average uplift force less than 200N, the pantograph has been modified two times since the first prototype pantograph was manufactured, By means of the following up characteristic test, low speed wind tunnel test, and high speed wind tunnel test for the prototype pantographs, we found that the aerodynamic uplift force did not exceed l60N at speed up to 350km/h and the aerodynamic noise was less than 88dB, that the following up characteristics of the prototype pantograph was excellent.

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Wind-induced vibrations and suppression measures of the Hong Kong-Zhuhai-Macao Bridge

  • Ma, Cunming;Li, Zhiguo;Meng, Fanchao;Liao, Haili;Wang, Junxin
    • Wind and Structures
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    • 제32권3호
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    • pp.179-191
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    • 2021
  • A series of wind tunnel tests, including 1:50 sectional model tests, 1:50 free-standing bridge tower tests and 1:70 full-bridge aeroelastic model tests were carried out to systematically investigate the aerodynamic performance of the Hong Kong-Zhuhai-Macao Bridge (HZMB). The test result indicates that there are three wind-resistant safety issues the HZMB encounters, including unacceptable low flutter critical wind speed, vertical vortex-induced vibration (VIV) of the main girder and galloping of the bridge tower in across-wind direction. Wind-induced vibration of HZMB can be effectively suppressed by the application of aerodynamic and mechanical measures. Acceptable flutter critical wind speed is achieved by optimizing the main girder form (before: large cantilever steel box girder, after: streamlined steel box girder) and cable type (before: central cable, after: double cable); The installations of wind fairing, guide plates and increasing structural damping are proved to be useful in suppressing the VIV of the HZMB; The galloping can be effectively suppressed by optimizing the interior angle on the windward side of the bridge tower. The present works provide scientific basis and guidance for wind resistance design of the HZMB.

Partial turbulence simulation and aerodynamic pressures validation for an open-jet testing facility

  • Fu, Tuan-Chun;Chowdhury, Arindam Gan;Bitsuamlak, Girma;Baheru, Thomas
    • Wind and Structures
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    • 제19권1호
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    • pp.15-33
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    • 2014
  • This paper describes partial turbulence simulation and validation of the aerodynamic pressures on building models for an open-jet small-scale 12-Fan Wall of Wind (WOW) facility against their counterparts in a boundary-layer wind tunnel. The wind characteristics pertained to the Atmospheric Boundary Layer (ABL) mean wind speed profile and turbulent fluctuations simulated in the facility. Both in the wind tunnel and the small-scale 12-Fan WOW these wind characteristics were produced by using spires and roughness elements. It is emphasized in the paper that proper spectral density parameterization is required to simulate turbulent fluctuations correctly. Partial turbulence considering only high frequency part of the turbulent fluctuations spectrum was simulated in the small-scale 12-Fan WOW. For the validation of aerodynamic pressures a series of tests were conducted in both wind tunnel and the small-scale 12-fan WOW facilities on low-rise buildings including two gable roof and two hip roof buildings with two different slopes. Testing was performed to investigate the mean and peak pressure coefficients at various locations on the roofs including near the corners, edges, ridge and hip lines. The pressure coefficients comparisons showed that open-jet testing facility flows with partial simulations of ABL spectrum are capable of inducing pressures on low-rise buildings that reasonably agree with their boundary-layer wind tunnel counterparts.

한국형 저비용 저고도 공중보급 체계용 낙하산 전개 특성 풍동시험 (Wind Tunnel Test for the Inflation Characteristics of the Korean Low Cost Low Altitude Aerial Delivery System)

  • 김승필;정인식;권기범;최윤석;정형석
    • 한국군사과학기술학회지
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    • 제20권3호
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    • pp.345-351
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    • 2017
  • A wind tunnel test for the scaled parachute models was performed to verify aerodynamic characteristics for practical usage of Korean low cost low altitude aerial delivery system. The cruciform shaped cargo parachute models for heavy and light weight were ejected into wind tunnel test section; and the drag forces acting on the models in steady condition were measured in accordance with velocity. Also, the maximum opening forces during inflation were obtained and captured by a high speed camera to analyze the inflation characteristics and evaluate the design of the low cost aerial delivery system. The results showed a reliable stability and met the design requirement of delivery operation system for R.O.K Air Force.

Unsteady aerodynamic force on a transverse inclined slender prism using forced vibration

  • Zengshun Chen;Jie Bai;Yemeng Xu;Sijia Li;Jianmin Hua;Cruz Y. Li;Xuanyi Xue
    • Wind and Structures
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    • 제37권5호
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    • pp.331-346
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    • 2023
  • This work investigates the effects of transverse inclination on an aeroelastic prism through forced-vibration wind tunnel experiments. The aerodynamic characteristics are tri-parametrically evaluated under different wind speeds, inclination angles, and oscillation amplitudes. Results show that transverse inclination fundamentally changes the wake phenomenology by impinging the fix-end horseshoe vortex and breaking the separation symmetry. The aftermath is a bi-polar, one-and-for-all change in the aerodynamics near the prism base. The suppression of the horseshoe vortex unleashes the Kármán vortex, which significantly increases the unsteady crosswind force. After the initial morphology switch, the aerodynamics become independent of inclination angle and oscillation amplitude and depend solely on wind speed. The structure's upper portion does not feel the effect, so this phenomenon is called Base Intensification. The phenomenon only projects notable impacts on the low-speed and VIV regime and is indifferent in the high-speed. In practice, Base Intensification will disrupt the pedestrian-level wind environment from the unleashed Bérnard-Kármán vortex shedding. Moreover, it increases the aerodynamic load at a structure base by as much as 4.3 times. Since fix-end stiffness prevents elastic dissipation, the load translates to massive stress, making detection trickier and failures, if they are to occur, extreme, and without any warnings.

회전 발사체용 마그너스 효과 특정기법의 개발 (Development of Magnus Effect Measurement Technique for Spinning Projectile)

  • 오세윤;김성철;이도관;최준호;안승기
    • 한국항공우주학회지
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    • 제35권1호
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    • pp.79-86
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    • 2007
  • 회전 발사체용 마그너스 효과 풍동실험 측정장치를 개발하였다. 국방과학연구소 풍동실험실에서는 고속풍동실험에 앞서 지상기능시험과 마그너스 저속풍동실험을 수행하였으며 마그너스 모형은 분당 약 6,000~10,000 회전하였으며, 속도 100 m/sec에서 측정한 마그너스 효과는 무차원 회전특성인자에 대해 선형적인 변화특성을 보였다. 동일형상 모형에 대해 미국 AEDC-4T 풍동에서 기 수행하였던 마그너스 측정결과와의 비교검토를 수행하였다.

항공기 저속 세로축 공력 계수 예측에 관한 연구 (Prediction of the Logitudinal Aerodynamic Coefficients of the Aircraft at Low Speed)

  • 강정훈
    • 한국항공운항학회지
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    • 제8권1호
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    • pp.83-95
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    • 2000
  • Lift, drag, pitching moment, what we call longitudinal aerodynamic coefficient, effects airplanes directly, so the method to find the accurate result quickly is an important factor from the beginning of the aircraft design. There are different ways to find aerodynamic coefficient such as empirical methods, numerical analysis methods, wind tunnel tests, and finally through an actual flight tests, but choosing the best methods depends on the due date or the cost. The accuracy varies on each design level, but all this methods have relationship to complement and balance each other, so by combining proper methods, the best result can be obtained. At this paper, empirical methods and numerical analysis method were experimented, compared, and reviewed to find the availability of each method and by combining two methods accurate result was obtained. So, we applied this methods to predict the aerodynamic coefficient on cruise configuration aircraft, and was able to obtain more accurate result on the low speed longitudinal aerodynamic coefficient. Also by watching there result, we are able to predict the errors before the actual wind tunnel test.

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