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NUMERICAL STUDY ON THE AERODYNAMIC CHARACTERISTICS OF A DUAL DUCTED-FAN AIRCRAFT DURING HOVERING, CLIMBING AND DESCENDING FLIGHTS 双管道风扇飞机悬停、爬升和下降飞行气动特性的数值研究
Han'gug jeonsan yuchegong haghoeji Pub Date : 2023-09-30 DOI: 10.6112/kscfe.2023.28.3.072
Y.J. Lee, J.D. Lee, H.S. Chung, H.S. Jeong, J.W. Yim, D.H. Park
{"title":"NUMERICAL STUDY ON THE AERODYNAMIC CHARACTERISTICS OF A DUAL DUCTED-FAN AIRCRAFT DURING HOVERING, CLIMBING AND DESCENDING FLIGHTS","authors":"Y.J. Lee, J.D. Lee, H.S. Chung, H.S. Jeong, J.W. Yim, D.H. Park","doi":"10.6112/kscfe.2023.28.3.072","DOIUrl":"https://doi.org/10.6112/kscfe.2023.28.3.072","url":null,"abstract":"Numerical analysis is conducted for a dual-ducted fan aircraft at hover, climb, and descent flight conditions to investigate the aerodynamics and stability characteristics. For practical and rapid analysis, the virtual disk method is employed and, a comparison with the results obtained from the sliding mesh method is performed to evaluate the validity of the method. During hovering flight, an imbalance in pitching moment arises at high collective pitch angles of the ducted-fans, which can deteriorates longitudinal stability. For climb flight condition, pitching moment increases and normal force decreases with climb velocity. Rolling and yawing moment exhibit minor changes at low collective pitch angles but significant changes occur at high pitch angles. For descent flight, thrust increases and pitching moment remains small as descent velocity increases. However, a considerable decrease in pitching moment with descent velocity is identified when the collective pitch angles are low.","PeriodicalId":496738,"journal":{"name":"Han'gug jeonsan yuchegong haghoeji","volume":"46 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135040853","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
ACCURACY OF THE FLOW FIELD AROUND A CYLINDER FROM VARIOUS IMMERSED BOUNDARY FORMULATION 不同浸入边界公式计算圆柱周围流场的精度
Han'gug jeonsan yuchegong haghoeji Pub Date : 2023-09-30 DOI: 10.6112/kscfe.2023.28.3.027
Wooseok Seo, Geunhyeok Choi, Seong-Jin Kim, Seungwon Shin
{"title":"ACCURACY OF THE FLOW FIELD AROUND A CYLINDER FROM VARIOUS IMMERSED BOUNDARY FORMULATION","authors":"Wooseok Seo, Geunhyeok Choi, Seong-Jin Kim, Seungwon Shin","doi":"10.6112/kscfe.2023.28.3.027","DOIUrl":"https://doi.org/10.6112/kscfe.2023.28.3.027","url":null,"abstract":"Calculating the flow field with complex geometry is one of the essential features of computational fluid dynamics. For finite volume formulation, a body fitted grid was usually utilized for such geometry. However, the immersed boundary method has become very popular these days since it can be applicable to a simple Cartesian coordinate system which uses finite difference schemes. It becomes much more effective along with two-phase flow modeling which is using continuous surface tension source formulation (CSF). There are several options for the immersed boundary techniques. Here, we are focused on the direct forcing method which is basically a ghost type approach. We tried to check the accuracy depending on forcing methods. Several forcing methods have been tested including linear velocity interpolation, stepwise or heaviside velocity filtering for the ghost nodes. We also tested a volume weighted velocity filtering approach for increased accuracy. For the benchmarking test, a flow field around the cylinder has been selected for comparison of the accuracy of different formulations.","PeriodicalId":496738,"journal":{"name":"Han'gug jeonsan yuchegong haghoeji","volume":"57 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135040856","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
OPTIMIZATION OF FRONT HATCH COVER OF HIGH SPEED TRAIN FOR REDUCTION OF AERODYNAMIC LOAD 高速列车前舱盖减小气动载荷的优化设计
Han'gug jeonsan yuchegong haghoeji Pub Date : 2023-09-30 DOI: 10.6112/kscfe.2023.28.3.109
Minho Kwak, Hyungmin Kang, Suhwan Yun, Taesoo Kwon
{"title":"OPTIMIZATION OF FRONT HATCH COVER OF HIGH SPEED TRAIN FOR REDUCTION OF AERODYNAMIC LOAD","authors":"Minho Kwak, Hyungmin Kang, Suhwan Yun, Taesoo Kwon","doi":"10.6112/kscfe.2023.28.3.109","DOIUrl":"https://doi.org/10.6112/kscfe.2023.28.3.109","url":null,"abstract":"Design optimization of frontal hatch cover of high speed train was preformed for reduction of aerodynamic load. For this, the shape function was used to model the frontal hatch cover. Then, a total of 15 design points were selected using three design variables: the length of the hatch cover, top-view curvature, and side-view curvature. A three-dimensional flow analysis was performed for each design point. Finally, the optimal shape was derived through optimization, and the aerodynamic load of the optimal shape was compared with that of baseline model. As a result, the length of the frontal hatch increased compared to the baseline model and the aerodynamic load was improved by about 20% from 4,890N to 3,920N through the optimized shape.","PeriodicalId":496738,"journal":{"name":"Han'gug jeonsan yuchegong haghoeji","volume":"22 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135040872","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
EVALUATION OF GRID DEPENDENCY OF PYFR-BASED ILES ANALYSIS FOR AIRFOIL AT MARS ATMOSPHERIC CONDITION 火星大气条件下基于pyfr的翼型分析网格依赖性评估
Han'gug jeonsan yuchegong haghoeji Pub Date : 2023-09-30 DOI: 10.6112/kscfe.2023.28.3.051
S.K. Yoon, D.H. Park
{"title":"EVALUATION OF GRID DEPENDENCY OF PYFR-BASED ILES ANALYSIS FOR AIRFOIL AT MARS ATMOSPHERIC CONDITION","authors":"S.K. Yoon, D.H. Park","doi":"10.6112/kscfe.2023.28.3.051","DOIUrl":"https://doi.org/10.6112/kscfe.2023.28.3.051","url":null,"abstract":"Mars atmospheric aircraft often encounter low Reynolds number conditions ranging from 10SUP4/SUP to 10SUP5/SUP, resulting in complex flow characteristics over airfoils, such as the formation of a laminar separation bubble(LSB). Accurate prediction of the LSB is important as it directly impacts the aerodynamic performance of the aircraft. To accurately capture the LSB, a high-fidelity analysis is required. In this study, we conducted PyFR-based implicit large eddy simulation using GPU acceleration to identify the effect of various grid parameters on aerodynamic performance and flow structure. Grid tests were performed under incompressible conditions with a Reynolds number = 30,000 and angle of attack = 8°, a short LSB which showed a high sensitivity to grid resolution was observed. The grid parameter study of the near-wall grid resolution, spanwise grid resolution, spanwise domain size, and far-field boundary size were conducted. The convergence of the aerodynamic coefficients, the location and length of the LSB were compared. It was analyzed that the spanwise grid resolution had the smallest effect on the aerodynamic coefficient, and it was confirmed that a certain level or more of the near-wall grid resolution and spanwise domain size are required to properly predict the LSB.","PeriodicalId":496738,"journal":{"name":"Han'gug jeonsan yuchegong haghoeji","volume":"48 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135040377","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
NUMERICAL STUDY OF EFFECT OF CARRIER GAS ON THE DEPOSITION UNIFORMITY INSIDE BATCH ALD REACTOR 载气对间歇式反应器内沉积均匀性影响的数值研究
Han'gug jeonsan yuchegong haghoeji Pub Date : 2023-09-30 DOI: 10.6112/kscfe.2023.28.3.035
J.H. You, J.C. Kim
{"title":"NUMERICAL STUDY OF EFFECT OF CARRIER GAS ON THE DEPOSITION UNIFORMITY INSIDE BATCH ALD REACTOR","authors":"J.H. You, J.C. Kim","doi":"10.6112/kscfe.2023.28.3.035","DOIUrl":"https://doi.org/10.6112/kscfe.2023.28.3.035","url":null,"abstract":"In the present study, flow simulations were performed to study the effect of carrier gases in a batch ALD reactor. Several cases varying the flow ratio between the carrier N2 and Side N2, which are injected into a main nozzle and side ones, respectively, were compared. The explanations about the wafer-to-wafer and within-wafer uniformity regarding film deposition were provided in terms of the flow analysis. The results showed that the flow rates injected from each nozzle hole are different from one another, leading to the non-uniformity inside the batch. The increase in Side N₂ can improve the uniformity at the single wafer. Even though the amount of Side N₂ also significantly influences the uniformity inside the whole batch reactor, its improvement is only achieved when the amount of Carrier N₂ is comparable to the Side N₂.","PeriodicalId":496738,"journal":{"name":"Han'gug jeonsan yuchegong haghoeji","volume":"33 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135040860","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
COMPUTATIONAL ANALYSIS OF FLOW CHARACTERISTICS OF RE-ENTRY VEHICLE AT LOW ALTITUDE 再入飞行器低空流动特性的计算分析
Han'gug jeonsan yuchegong haghoeji Pub Date : 2023-09-30 DOI: 10.6112/kscfe.2023.28.3.099
B.G. Park, S.H. Ryu, S.J. Jo, R.S. Myong
{"title":"COMPUTATIONAL ANALYSIS OF FLOW CHARACTERISTICS OF RE-ENTRY VEHICLE AT LOW ALTITUDE","authors":"B.G. Park, S.H. Ryu, S.J. Jo, R.S. Myong","doi":"10.6112/kscfe.2023.28.3.099","DOIUrl":"https://doi.org/10.6112/kscfe.2023.28.3.099","url":null,"abstract":"Re-entry vehicles fly through each layer of the atmosphere with different states during descent to Earth. In this study, we investigate the characteristics of the front bow shock wave and rear irregular wake flow of a model re-entry vehicle in the low-altitude transitional regime using CFD based on Navier-Stokes equations. Five species and seventeen species models is used to describe the reaction that might be present at supersonic and hypersonic speeds. It was shown that bow shock wave occurs farther in low-altitude transitional regimes than in high-altitude rarefied regimes. As altitude changes, the difference in heat flux appears to be greater than that of surface temperature due to the influence of heat energy from chemical reactions. Additionally, through a comparison of wake flows, it was confirmed that at lower altitudes, the irregularities of the boundary layer, separation, recompression, and recirculation flows increased, making the wake flows of the vehicle more irregular.","PeriodicalId":496738,"journal":{"name":"Han'gug jeonsan yuchegong haghoeji","volume":"48 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135040859","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
AIRFOIL DESIGN OPTIMIZATION FOR IMPROVING AERODYNAMIC PERFORMANCE OF UAV 提高无人机气动性能的翼型优化设计
Han'gug jeonsan yuchegong haghoeji Pub Date : 2023-09-30 DOI: 10.6112/kscfe.2023.28.3.008
D.I. Jang, W.T. Lee, M.J. Kang, G.H. Bae, S.U. Oh, H. Lee, R.S. Myong
{"title":"AIRFOIL DESIGN OPTIMIZATION FOR IMPROVING AERODYNAMIC PERFORMANCE OF UAV","authors":"D.I. Jang, W.T. Lee, M.J. Kang, G.H. Bae, S.U. Oh, H. Lee, R.S. Myong","doi":"10.6112/kscfe.2023.28.3.008","DOIUrl":"https://doi.org/10.6112/kscfe.2023.28.3.008","url":null,"abstract":"A computational study for improving aerodynamic performance was conducted by optimizing the airfoil shape of an Unmanned Aerial Vehicle (UAV). The baseline airfoil, FX73-CL2-152, was selected, and based on this shape, a Kriging approximation model and genetic algorithm were used to find an airfoil shape that maximizes lift and minimizes drag. The optimized airfoil shape was applied to a full-scale model similar to the MQ-1 Predator, and it was confirmed that the lift coefficient and endurance factor increased by 9.5% and 7.3%, respectively. These results demonstrate that the optimization of the airfoil can significantly contribute to the overall performance of the UAV, including reducing takeoff and landing distances, improving structural stability, and increasing fuel load. Furthermore, this research could contribute to enhancing UAVs","PeriodicalId":496738,"journal":{"name":"Han'gug jeonsan yuchegong haghoeji","volume":"33 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135040692","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
NUMERICAL PREDICTION OF THE CAVITATION AROUND AN UNDERWATER BODY CONSIDERING SURGE MOTION 考虑浪涌运动的水下物体空化的数值预测
Han'gug jeonsan yuchegong haghoeji Pub Date : 2023-09-30 DOI: 10.6112/kscfe.2023.28.3.042
J.I. Kim, I.R. Park, S.B. Suh, M.J. Kim, G.R. Ku, T.W. Kim, S.H. Kim
{"title":"NUMERICAL PREDICTION OF THE CAVITATION AROUND AN UNDERWATER BODY CONSIDERING SURGE MOTION","authors":"J.I. Kim, I.R. Park, S.B. Suh, M.J. Kim, G.R. Ku, T.W. Kim, S.H. Kim","doi":"10.6112/kscfe.2023.28.3.042","DOIUrl":"https://doi.org/10.6112/kscfe.2023.28.3.042","url":null,"abstract":"This paper presents the numerical prediction of the forward speed and moving distance of an underwater body including the analysis of the unsteady characteristics of cavitation developing around the body according to speed change. The flow was assumed to be two-phase incompressible turbulent flow and solved by using the unsteady Reynolds averaged Navier-Stokes method that includes a cavitation model explaining the phase change between the water and vapour. The temporal change of the speed and moving distance of the underwater body estimated from the 1DoF motion analysis showed a satisfactory agreement with the measured results in the underwater test. In addition, the time variations of the cavity predicted along with the speed change of the body also showed a reasonable agreement with the cavity observation of the underwater test. Through this study, we were able to properly explain the drag and speed changes of the underwater body linked to the development of the cavity.","PeriodicalId":496738,"journal":{"name":"Han'gug jeonsan yuchegong haghoeji","volume":"60 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135040851","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
THERMAL FLOW FIELD ANALYSIS OF HEAT SINK FOR IMPROVING COOLING EFFICIENCY OF AVIONICS EQUIPMENT 提高航空电子设备冷却效率的散热器热流场分析
Han'gug jeonsan yuchegong haghoeji Pub Date : 2023-09-30 DOI: 10.6112/kscfe.2023.28.3.083
M.G. Kang, D.H. Kim, D.I. Jang, H. Lee, R.S. Myong
{"title":"THERMAL FLOW FIELD ANALYSIS OF HEAT SINK FOR IMPROVING COOLING EFFICIENCY OF AVIONICS EQUIPMENT","authors":"M.G. Kang, D.H. Kim, D.I. Jang, H. Lee, R.S. Myong","doi":"10.6112/kscfe.2023.28.3.083","DOIUrl":"https://doi.org/10.6112/kscfe.2023.28.3.083","url":null,"abstract":"The amount of heat generated by avionics equipment in aircraft increases as more electrical components become compact. Avionics directly affects airplane performance, and thermal management systems play an important role in maintaining safety and performance. In this study, thermal analysis of avionics equipment mounted on aircraft was conducted to improve performance by considering shape modification and fan operation. A temperature difference of up to 55°C was observed for the basic shape when the fan was not operated. Several attempts such as the change of shape and material were made, but it was observed that the devices reached an excessive temperature. It was shown that the devices reached the proper level of temperature where forced convection was imposed by operating the fan. This study will provide critical information for the development of improved cooling methods for avionics and derivation of environmental conditions.","PeriodicalId":496738,"journal":{"name":"Han'gug jeonsan yuchegong haghoeji","volume":"43 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135040854","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
COMPARATIVE ANALYSIS OF WIND LOADS USING THE POWER THE LOAD-BASED WIND LOAD AND ARCHITECTURE-BASED ELEVATION DISTRIBUTION FACTOR(Kzr) 基于功率、基于荷载的风荷载与基于建筑的高程分布系数(Kzr)的风荷载比较分析
Han'gug jeonsan yuchegong haghoeji Pub Date : 2023-09-30 DOI: 10.6112/kscfe.2023.28.3.001
Y.J. Kim, Y.M. Jo
{"title":"COMPARATIVE ANALYSIS OF WIND LOADS USING THE POWER THE LOAD-BASED WIND LOAD AND ARCHITECTURE-BASED ELEVATION DISTRIBUTION FACTOR(Kzr)","authors":"Y.J. Kim, Y.M. Jo","doi":"10.6112/kscfe.2023.28.3.001","DOIUrl":"https://doi.org/10.6112/kscfe.2023.28.3.001","url":null,"abstract":"Wind load is an essential consideration in all building design. It refers to the force of the wind on the building and is a crucial factor in determining the strength and stability of the structure. There are several reasons why it is important to set wind load for calculating building wind. Firstly, wind load is one of the significant loads that a building must withstand. Resistance to wind load is essential to prevent structural damage during high wind events such as storms, hurricanes, and tornadoes. By setting wind load, engineers can determine the wind pressure that the building will experience and design the structure accordingly. Secondly, wind load affects the performance and energy efficiency of the building. The front of the building is typically the primary obstacle to wind load and can have a significant impact on the building","PeriodicalId":496738,"journal":{"name":"Han'gug jeonsan yuchegong haghoeji","volume":"60 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135040866","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
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