• 한국항공운항학회지
• /
• 제8권1호
• /
• pp.83-95
• /
• 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.

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2011년도 추계학술대회 논문집
• /
• pp.658-663
• /
• 2011

The purpose of this study is to develop an air-passing soundproofing panel with more improved structure to reduce the $CO_2$ emission and installation cost. To reduce the emission of $CO_2$ ; it is suggested to choose low $CO_2$ emission material relative to the aluminum and to reduce the materials by developing a specially designed air-passing soundproofing panel structure. First of all, we performed the flow analysis to predict the wind pressure according to the open angle of the air-passing soundproofing panel and the noise level analysis at the receiver point. To verify the simulation, a prototype of the soundproofing panel was made. The flow test in the wind tunnel and load test were performed. The economic evaluation for the installation of the air-passing soundproofing panel was performed and specifications of the installation was prepared. As the results of this research, it was verified that the wind load was reduced about 40% to that of the conventional one at 25m/s wind speed in the wind tunnel test. By applying the 4m span soundproofing wall with air-passing soundproofing panel and under the cost of 250 thousand $won/m^2$ instead of the conventional 2m span panel, the installation cost will always be lowered than the conventional one in the combination of (60:40~50:50) conventional to air-passing soundproofing panel from the economic evaluation. The 20% reduction of $CO_2$ was found by changing the 50% of aluminum soundproof panel to air-passing soundproofing panel.

• Journal of Advanced Marine Engineering and Technology
• /
• 제40권4호
• /
• pp.330-335
• /
• 2016

본 논문에서는 설계된 100 W급 헬리컬 수직축 풍력발전기의 공기 역학적 출력 및 유동 특성에 관하여 연구하였다. 이를 위하여 100 W급 헬리컬 수직축 풍력발전기 로터를 설계하였고 풍동 시험과 동일한 환경을 적용한 3차원 전산유동해석을 수행하였다. 전산유동해석 결과를 통하여 공기 역학적 출력과 헬리컬 유동 특성을 확인하였다. 마지막으로 실제 크기의 수직축 풍력발전기에 대한 풍동 시험을 수행하여 전산유동해석에서 예측한 공기역학적 출력과 비교 검증하여 전산유동해석 기법의 타당성을 확인하였다.

• 한국항공우주학회지
• /
• 제41권4호
• /
• pp.261-267
• /
• 2013

본 논문에서는 헬리콥터 전진비행 조건에서 플래핑모션에 대하여 축소 로터 실험을 통하여 실험결과와 이론적인 예측결과를 비교하였다. 축소로터 성능 실험은 충남대학교 아음속 풍동에서 수행하였으며 1.8 x 1.8m의 개방형 시험부를 사용하였다. 전진비행조건에서의 실험 결과에 의하면 축소로터의 전진비행조건에서의 추력 결과를 고정한 조건에서 동력계수는 차이가 있는 것을 확인 할 수 있었다. 또한, 공력 성능 측정 결과와 이론적인 예측결과의 비교를 통하여 헬리콥터의 플랩핑 각도의 범위에 대하여 비교하여 보았다. Coning 각도, 횡방향과 종방향에 대한 플래핑 각도에 대해서는 실험결과와 예측결과의 유사함을 확인하였다.

• Journal of Mechanical Science and Technology
• /
• 제16권1호
• /
• pp.125-131
• /
• 2002

A low speed wind tunnel test was conducted for a canard airplane model in KARI LSWT. The purpose of the presented paper is to investigate the proper testing approach to correct tare precisely and the interference effects for the canard models which has 21% of canard-to-wing area ratio. Most of tests were performed with image system installation for various elevator deflection conditions at the flexed canard incidence angles. To evaluate the effectiveness of the image system, the obtained correction quantity at an zero elevator setting condition with image system was applied to the rest of elevator deflections and compared with the acquired results for all elevator deflections with image system. Test result showed that the amount of correction quantities were strongly dependent on the elevator deflections, and the difference in aerodynamic coefficients for two approaches was gradually amplified as the elevator deflection angles increased. An adoption of the image system was strongly recommended for the higher canard-to -wing area ratio model, if a proper level of accuracy was required.

• 한국항공우주학회지
• /
• 제45권3호
• /
• pp.194-201
• /
• 2017

EFD-CFD 비교 워크샵 case 1의 모델로 한국항공우주연구원에서 개발된 KARI-11-180 익형이 선정되었다. 익형 풍동시험은 $0.6m{\times}3.0m$ 모델을 사용하여 KARI LSWT에서 최대 레이놀즈수 3.0E6까지 수행되었다. 익형 형상 및 Cl, Cd 그리고 Cp를 포함한 시험자료가 2015년 KSAS 춘계학술대회에서 공개되었으며, KFLOW, FLUENT 및 STAR-CCM+를 사용한 전산유체해석결과가 2015년 KSAS 추계학술대회에서 공개되었다. 본 논문에는 2015년 발표된 시험 및 전산해석결과를 요약하여 수록하였으며, 시험결과를 포함한 전산해석 결과들 간의 비료결과도 요약수록 하였다.

• 한국항공우주학회지
• /
• 제35권7호
• /
• pp.575-580
• /
• 2007

카나드 형상 고기동 항공기의 개념 설계 단계에서 높은 받음각 항공기 정적 안정성 분석을 위해 저속 소형 풍동시험을 수행하였다. 본 연구에서는 1/50축척의 일반적인 카나드-동체-날개 형상을 소형 풍동시험 모델로 사용하였다. 높은 받음각 비선형특성을 포함한 정적 안정성을 분석하기 위하여 카나드 굽힘에 따른 수직 꼬리 날개 효과를 분석하였다. 또한 높은 받음각에서 Nose Chine 효과를 분석하였다. 실험 연구에서 얻은 결과를 토대로 카나드 형상 항공기 높은 받음각 정적 안정성에 미치는 형상 변화 효과를 분석할 수 있었다.

• 한국항공우주학회지
• /
• 제30권4호
• /
• pp.38-43
• /
• 2002

본 연구에서는 항공기 날개 표면에서의 공력 하중 분포를 측정하는 풍동 시험 및 모형 설계와 제작에 대한 연구를 수행하였다. 모형 날개에는 총 447개의 압력공을 표면에 수직하게 제작하였으며, 날개 내부에 설치한 압력 tube를 통해 모형 내부에 설치된 총 8개의 EPS modules에 연결하여 PSI-8400 system을 사용 압력 분포를 측정하였다. 풍동 시험은 국방과학연구소 아음속풍동을 사용 50m/sec에서 정속모드로 수행하였다. 시험은 하중분포 예측을 위해 받음각과 옆미끄럼각 변위, 플랩 및 외부장착물 설치에 따른 날개에서의 하중분포 측정을 위해 수행하였다. 본 시험 결과로 항공기 날개 구조 최적 설계 자료로의 활용 및 전산유체역학의 결과 검증에 활용 할 수 있을것으로 판단된다.

• International Journal of Aeronautical and Space Sciences
• /
• 제4권1호
• /
• pp.19-25
• /
• 2003

A low speed wind tunnel test for the canard airplane model was conducted in KARI LSWT. To measure the required level of accuracy, the image system was applied for all elevator deflection and different canard incidence conditions. By doing so, the difference in aerodynamic characteristics between the forward swept and straight canards can be precisely evaluated, and the pros and cons of both canards arrangements can be discussed. Compared with both canard configurations at the same incidence angle setting, the straight canard has benefits in lift and drag, and the slope of pitching moment increases more moderately than the forward swept canard. The listed data and discussion would be useful to whom wants to design a canard airplane.

• Wind and Structures
• /
• 제25권3호
• /
• pp.233-259
• /
• 2017

Investigations on simulated near-surface atmospheric boundary layer (ABL) in an open-jet facility are carried out by conducting experimental tests on small-scale models of low-rise buildings. The objectives of the current study are: (1) to determine the optimal location of test buildings from the exit of the open-jet facility, and (2) to investigate the scale effect on the aerodynamic pressure characteristics. Based on the results, the newly built open-jet facility is well capable of producing mean wind speed and turbulence profiles representing open-terrain conditions. The results show that the proximity of the test model to the open-jet governs the length of the separation bubble as well as the peak roof pressures. However, test models placed at a horizontal distance of 2.5H (H is height of the wind field) from the exit of the open-jet, with a width that is half the width of the wind field and a length of 1H, have consistent mean and peak pressure coefficients when compared with available results from wind tunnel testing. In addition, testing models with as large as 16% blockage ratio is feasible within the open-jet facility. This reveals the importance of open-jet facilities as a robust tool to alleviate the scale restrictions involved in physical investigations of flow pattern around civil engineering structures. The results and findings of this study are useful for putting forward recommendations and guidelines for testing protocols at open-jet facilities, eventually helping the progress of enhanced standard provisions on the design of low-rise buildings for wind.