• International Journal of Aeronautical and Space Sciences
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• 제17권2호
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• pp.260-267
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• 2016

The design process of blended inlet body (BIB) for the preliminary design of a near-space high supersonic unmanned aerial vehicle (HSUAV) is presented. The mass flow rate and cowl area of inlet at a design point are obtained according to the cruise condition of the HSUAV. A mixed-compression axisymmetric supersonic inlet section with a fixed geometry reasonably matching the high supersonic cruise state is created by using the inviscid theory of aerodynamics. The inlet section is optimized and used as a baseline section for the BIB design. Three BIB concepts for the HSUAV are proposed, and their internal aerodynamic characteristics of inlet are evaluated using Euler computational fluid dynamics (Euler CFD) solver. The preferred concept is identified, in which the straight leading edge of the baseline HSUAV configuration is modified into the convex leading edge to accommodate the inlet and meet the requirements of the cowl area to capture the sufficient air flow. The total recovery of inlet for the preferred BIB concept and the aerodynamic characteristics of the modified HSUAV configuration are verified using Navier-Stokes computational fluid dynamics (NS CFD) solver. The validation indicates that the preferred BIB concept can meet both the requirements of the inlet and aerodynamic performance of the HSUAV.

• 한국실내디자인학회논문집
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• 제21권5호
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• pp.272-279
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• 2012

Apartments with a southern exposure are often thought to have advantages in receiving winter sunlights and summer natural ventilation. However, as due-south-apartments increase recently, the consideration for residential environment for households with no southern exposure is necessary. In case of due-south-apartments, residents prefer east-sided apartments than west facing apartments which might receive more hot sunlight in the afternoon; however in case of west-oriented apartments with active ventilation, the interior area is bright until late afternoon without unpleasant heat and has advantage in light environment aspects. This study aims to compare and analyze merits and demerits of air flow and sunlighted environment of buildings through sunshine duration simulation using CFD simulation ad sunlights about southeast-sided and southwest-sided apartments based on general opinions for apartment directions. As results of the interior natural ventilation analysis, as the average air flow speed in southwest-sided apartments was 1m/s faster than that of southeast-sided, it has effects of lowering sensory temperature of residents in summer, and for sunlighted environment, southwest-sided apartments are advantageous for sunlighted area for duration time inside. As a result of the research, the calculation of physical residential environment of apartment residential space should be reached through integrated evaluation of natural ventilation and sunlighted time from placement and facing direction of the buildings considering characteristics and environment of each apartment, not based on general opinions.

• 한국항공우주학회지
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• 제47권7호
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• pp.479-488
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• 2019

순항 유도탄은 비행기처럼 날개와 제트엔진을 사용하여 상당 거리를 순항한 후 최종 목표에 도달하는 유도탄이다. 적의 레이더에 쉽게 포착되지 않을뿐더러 아음속 장거리 순항이 가능해야 하므로, RCS 저감과 향상된 공력성능을 고려한 통합 설계가 필수적이다. 본 연구에서는 Taurus 유도탄과 유사한 순항 유도탄 모델을 설계한 후, Physical Optics (PO; 물리적 광학) 기법과 Navier-Stokes CFD 코드를 사용하여 비행체의 RCS와 공력특성을 분석하였다. 이를 바탕으로 공력성능 향상과 RCS 저감 기술이 적용된 순항 유도탄의 최적 형상을 도출하였다.

• 한국분무공학회지
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• 제25권4호
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• pp.162-169
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• 2020

The worldwide focus on reducing the emissions, fuel and lubricant consumption in T-GDI engines is leading engineers to consider the crankcase ventilation and oil mist separation system as an important means of control. In today's passenger cars, the oil mist separation systems mainly use the inertia effect (e.g. labyrinth, cyclone etc.). Therefore, this study has investigated high efficiency cylinder head-integrated oil-mist separator by using a compact multi-impactor type oil mist separator system to ensure adequate oil mist separation performance. For this purpose, engine dynamometer testing with oil particle efficiency measurement equipment and 3D two-phase flow simulation have been performed for various engine operating conditions. Tests with an actual engine on a dynamometer showed oil aerosol particle size distributions varied depending on operating conditions. For instance, high rpm and load increases bot only blow-by gases but the amount of small size oil droplets. Submicron-sized particles (less than 0.5 ㎛) were also observed. It is also found that the impactor type separator is able to separate nearly no droplets of diameter lower than 3 ㎛. CFD results showed that the complex aerodynamics processes that lead to strong impingement and break-up can strip out large droplets and generate more small size droplets.

• 한국산학기술학회논문지
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• 제12권2호
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• pp.985-992
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• 2011

복합 후처리장치의 최적 모델 개발을 위해 반응기 내부 유동 특성 및 유량 분배 수준 등과 관련지어 3차원 전산유체역학(CFD)을 수행하였다. 백필터의 각 격실별로 유량 분배가 크게 차이가 발생해 반건식 반응기(SDR)에 편류현상이 발생할 것으로 예측되어 백필터에 균등한 유량 분배를 위한 구조 개선이 시급한 것으로 나타났다. 이를 위해, 장치에 3가지 수정.보완(플래넘 구조 개선, 풍도 오리피스 설치, 복수의 흡인 덕트 설치)이 이루어졌다. 이 중에서 플래넘 구조 개선, 풍도 오리피스 설치가 가장 합리적일 것으로 판단된다. 본 해석을 이용하여 수정 보완한 배가스복합 후처리장치는, 반건식 반응기와 백필터 처리부가 일체화되어 있어 장치가 콤팩트하고 설치면적이 적으며 운영 및 관리가 매우 편리할 것으로 판단된다.

• 한국산학기술학회논문지
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• 제11권11호
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• pp.4656-4663
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• 2010

본 연구에서는 복합 후처리장치의 최적 모델 개발을 위해 반응기 내부 유동 특성 및 유량 분배 수준, 공기 연령, 체류시간 등과 관련지어 3차원 전산유체역학(CFD)을 수행하였다. 백필터의 각 격실별로 유량 분배가 크게 차이가 발생해 반건식 반응기(SDR)에 편류현상이 발생할 것으로 예측되어 백필터에 균등한 유량 분배를 위한 구조 개선이 시급한 것으로 나타났다. 또한 SDR의 유입구 구조 변경을 통해 반응기 내부의 속도장과 체류시간 분포 특성을 개선할 수 있는 것으로 나타났다. 본 해석을 이용하여 수정 보완한 배가스 복합 후처리장치는, 반건식 반응기와 백필터 처리부가 일체화되어 있어 장치가 콤팩트하고 설치면적이 적으며 운영 및 관리가 매우 편리할 것으로 판단된다.

• 한국광학회지
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• 제25권5호
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• pp.245-253
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• 2014

본 논문에서는 사거리가 수백 km에 이르는 장거리 미사일의 화염을 발사 초기에 탐지할 수 있는 적외선 카메라에 대한 현실적 영상성능 수치모사 결과를 제시한다. 적외선 카메라는 중적외선 대역용 다수의 렌즈로 구성된 굴절식 광학계이다. 관측대상과 배경의 모델링 전체를 포함하는 규모의통합적 광선추적을 수행함으로 카메라를 통해 보는 영상과 검출기에 도달하는 빛의 세기에 대한 정보를 획득하였다. 관측대상이 되는 미사일 화염의 방사휘도(radiance)는 CFD 타입의 복사전달 기법으로 계산하였으며 이를 광원으로 삽입하여 광선추적을 수행하였다. 관측배경이 되는 대기 모델은 MODTRAN을 사용하여 열복사의 경로, 단일/다중 산란 복사와 투과율을 계산하였다. 광선추적 수치모사의 결과로써 관측대상의 이미지와 도달한 복사전달 성능(radiometric performance)의 검증을 통해 적외선 카메라가 요구사항을 만족함을 입증하였다.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2008년 영문 학술대회
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• pp.690-699
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• 2008

In this paper a conventional approach for design and analysis of subsonic air vehicle is used. First of all subsonic aerodynamic coefficients are calculated using Computational Fluid Dynamics(CFD) tools and then wind-tunnel model was developed that integrates vehicle components including control surfaces and initial data is validated as well as refined to enhance aerodynamic efficiency of control surfaces. Experimental data and limited computational fluid dynamics solutions were obtained over a Mach number range of 0.5 to 0.8. The experimental data show the component build-up effects and the aerodynamic characteristics of the fully integrated configurations, including control surface effectiveness. The aerodynamic performance of the fully integrated configurations is comparable to previously tested subsonic vehicle models. Mathematical model of the dynamic equations in 6-Degree of Freedom(DOF) is then simulated using MATLAB/SIMULINK to simulate trajectory of vehicle. Effect of altitude on range, Mach no and stability is also shown. The approach presented here is suitable enough for preliminary conceptual design. The trajectory evaluation method devised accurately predicted the performance for the air vehicle studied. Formulas for the aerodynamic coefficients for this model are constructed to include the effects of several different aspects contributing to the aerodynamic performance of the vehicle. Characteristic parameter values of the model are compared with those found in a different set of similar air vehicle simulations. We execute a set of example problems which solve the dynamic equations to find the aircraft trajectory given specified control inputs.

• 국제학술발표논문집
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• The 7th International Conference on Construction Engineering and Project Management Summit Forum on Sustainable Construction and Management
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• pp.14-23
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• 2017

In high-density high-rise cities such as Hong Kong, buildings account for nearly 90% of energy consumption and 61% of carbon emissions. Therefore, it is important to study the design of buildings, especially high-rise buildings, to achieve lower carbon emissions in the city. The carbon emissions of a building consist of embodied carbon from the production of construction materials and operational carbon from energy consumption during daily operation (e.g., air-conditioning and lighting). An integrated analysis of both types of carbon emissions can strengthen the design of low carbon buildings, but most of the previous studies concentrated mainly on either embodied or operational carbon. Therefore, the primary objective of this study is to develop a holistic methodology framework considering both embodied and operational carbon, in order to enhance the sustainable design of low carbon high-rise buildings. The framework will be based on the building information modeling (BIM) technology because BIM can be integrated with simulation systems and digital models of different disciplines, thereby enabling a holistic design and assessment of low carbon buildings. Structural analysis program is first coupled with BIM to validate the structural performance of a building design. The amounts of construction materials and embodied carbon are then quantified by a BIM-based program using the Dynamo programming interface. Operational carbon is quantified by energy simulation software based on the green building extensible Markup Language (gbXML) file from BIM. Computational fluid dynamics (CFD) will be applied to analyze the ambient wind effect on indoor temperature and operational carbon. The BIM-based framework serves as a decision support tool to compare and explore more environmentally-sustainable design options to help reduce the carbon emissions in buildings.

• International Journal of Fluid Machinery and Systems
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• 제8권3호
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• pp.142-154
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• 2015

Nowadays, computational fluid dynamics is commonly used by design engineers to evaluate and compare losses in hydraulic components as it is less expensive and less time consuming than model tests. For that purpose, an automatic tool for casing and distributor analysis will be presented in this paper. An in-house mesh generator and a Reynolds Averaged Navier-Stokes equation solver using the standard $k-{\omega}$ shear stress transport (SST) turbulence model will be used to perform all computations. Two solvers based on the C++ OpenFOAM library will be used and compared to a commercial solver. The performance of the new fully coupled block solver developed by the University of Lucerne and Andritz will be compared to the standard 1.6ext segregated simpleFoam solver and to a commercial solver. In this study, relative comparisons of different geometries of casing and distributor will be performed. The present study is thus aimed at validating the block solver and the tool chain and providing design engineers with a faster and more reliable analysis tool that can be integrated into their design process.