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Research Article
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NUMERICAL INVESTIGATION OF A NOVEL HEAT EXCHANGER DESIGN FOR THE COOLING OF ELECTRO OPTICAL TRACKING SYSTEM IN EXTREME ENVIRONMENTAL CONDITIONS
극한 환경의 무기체계에 적용되는 전자광학추적장비(Electro Optical Tracking System)의 냉각을 위한 신개념 열교환기의 설계 및 수치적 연구
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S. Lee, H. Kwon, H.P. Park, S.W. Lee, D.H. Park, J.I. Bae, H. Park
이성빈, 권화빈, 박형필, 이상우, 박동혁, 배종인, 박희성
- This study proposes a new concept of a heat exchanger for cooling of Electro-Optical Tracking System applied to weapon systems and numerically …
- This study proposes a new concept of a heat exchanger for cooling of Electro-Optical Tracking System applied to weapon systems and numerically analyzes its heat transfer performance. The proposed heat exchanger divides into an internal system, which includes a heat source, and an external system that receives external air. Both systems feature a symmetrical structure and comprise an Dual impeller, 14 heat pipe, 14 heat pipe bracket, and casing. A center plate is installed to serve both as a complete separator of the systems. To analyze the heat transfer performance, a numerical study is conducted using the Generalized k-omega turbulence model. The rotation speed of the impeller is set between 7,000 and 9,000 rev/min. The fluid flow into the heat exchanger by the rotation of the impeller. The fluid is separated by the heat pipe, forming a recirculation area. The results show that as the impeller rotational speed increases, the heat transfer rate improves by an average of 13.71% and 15.15% in the internal and external systems, respectively. The heat exchanger proposed in this study is anticipated to serve as foundational research for the cooling of Electro-Optical Tracking System in extreme environments in the future. - COLLAPSE
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NUMERICAL INVESTIGATION OF A NOVEL HEAT EXCHANGER DESIGN FOR THE COOLING OF ELECTRO OPTICAL TRACKING SYSTEM IN EXTREME ENVIRONMENTAL CONDITIONS
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Research Article
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OPTIMIZATION OF BIOMIMETIC TUBERCLE FOR IMPELLER IN A CENTRIFUGAL PUMP
원심 펌프의 임펠러의 생체모방공학 기반 결절 형상 최적화
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C. Oh, J. Lee, J. Park, S. Kang
오창종, 이준희, 박진규, 강성원
- In this study, a biomimetic tubercle shape was applied to the trailing edge of a centrifugal pump impeller in the purpose of …
- In this study, a biomimetic tubercle shape was applied to the trailing edge of a centrifugal pump impeller in the purpose of increasing pump efficiency. Shape optimization was conducted to maximize composite pump efficiency, and the effect of flow control of the tubercle on performance improvement was analyzed. The shape optimization was carried out in two stages: sine wave shape of the tubercle was optimized, and based on the results, separate height of the tubercle was adjusted via the second optimization process. Application of the tubercle to the trailing edge increased the efficiency and reduced the turbulent kinetic energy compared to the original pump. Depending on the sinusoidal design parameters, the efficiency increased and TKE decreased as the height and number of tubercles increased. The optimization results of separate height tubercle showed that the specific tubercle has relatively larger effect on the efficiency. - COLLAPSE
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OPTIMIZATION OF BIOMIMETIC TUBERCLE FOR IMPELLER IN A CENTRIFUGAL PUMP
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Research Article
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CODE DEVELOPMENT FOR ANALYSIS AROUND PUMPJET PROPULSORS USING SINGLE BLADE PASSAGE METHOD
단일 날개 경로 기법을 이용한 펌프젯 추진기 주위 유동 해석을 위한 코드 개발
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H. Kim, I.D. Suh, I. Lee, J.-H. Lee, S.H. Rhee
김한준, 서인덕, 이인수, 이준혁, 이신형
- This research presents a numerical investigation of the open water performance of a pumpjet propulsor. The Single Blade Passage method was employed …
- This research presents a numerical investigation of the open water performance of a pumpjet propulsor. The Single Blade Passage method was employed to simulate the rotational motion of the pumpjet's rotor. This method, which involves the direct rotation of the rotational area, simulates the rotational motion effectively. Since it constructs the domain using only a single blade and its surrounding grid, this method is cost-effective. The study applied this method to a pumpjet propulsor designed by KRISO. The present numerical results were validated with the results of the open water test performed in the large cavitation tunnel at KRISO. Changes in the thrust and torque of pumpjet propulsor according to advance ratio were analyzed by using SNUFOAM, which was open-source toolkit CFD code based on the OpenFOAM. The flow around a pumpjet propulsor were compared with previous studies. - COLLAPSE
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CODE DEVELOPMENT FOR ANALYSIS AROUND PUMPJET PROPULSORS USING SINGLE BLADE PASSAGE METHOD
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Research Article
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COMPUTATIONAL ANALYSIS OF ICE ACCRETION AND AERODYNAMICS EFFECTS OF UAV IN SLD ENVIRONMENT
SLD 환경에서 무인기의 결빙 증식과 공력 특성에 관한 전산 해석
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J.H. Park, W.T. Lee, S.U. Oh, G. An, H. Lee, R.S. Myong
박재현, 이원태, 오승욱, 안건, 이학진, 명노신
- When an unmanned aerial vehicle(UAV) encounters cloud layers with high humidity and sub-freezing temperatures, such as ice particles or supercooled water droplets, …
- When an unmanned aerial vehicle(UAV) encounters cloud layers with high humidity and sub-freezing temperatures, such as ice particles or supercooled water droplets, the UAV's surface can undergo icing. Icing accretion on an aircraft can lead to various issues, including reduced stall angle and decreased controllability, which can potentially result in a direct threat to safe flight. In this study, a comparative analysis was conducted on the ice accretion occurring on UAV under the non-SLD condition, which is the continuous maximum(CM) condition of FAR Appendix C, and the freezing rain SLD condition of Appendix O by computational simulation. More ice is accreted in the SLD condition than in the non-SLD condition, but aerodynamic performance is reduced less than non-SLD condition. This is because the ice shape of SLD conditions is created streamlined along the UAV surface. In the future, this study can be extended to the design of ice protection systems and utilized in icing certification for UAVs in SLD conditions. - COLLAPSE
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COMPUTATIONAL ANALYSIS OF ICE ACCRETION AND AERODYNAMICS EFFECTS OF UAV IN SLD ENVIRONMENT
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Research Article
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CONSTRUCTION AND EVALUATION OF AERODYNAMIC DATABASE FOR UAM FLIGHT SIMULATOR INTEGRATIONPART Ⅰ: LIFT-CRUISE TYPE
UAM 비행 시뮬레이터 탑재용 공력 데이터베이스 구축 및 평가Part Ⅰ: 리프트-크루즈형
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W.S. Lee, M.S. Tai, D.H. Kim, S.W. Choi, D.H. Park
이우승, 태명식, 김다혜, 최성욱, 박동훈
- The stability and operational procedures of UAM aircraft are validated using a flight simulator that simulates various flight scenarios in a virtual …
- The stability and operational procedures of UAM aircraft are validated using a flight simulator that simulates various flight scenarios in a virtual environment. The development of flight simulators requires the construction of an aerodynamic database(DB) reflecting the characteristics of various UAM configurations. In this study, a time-efficient approach for constructing an aerodynamic DB of lift-cruise type aircraft was defined. This approach applied the concept of the component build-up method to the design of the aerodynamic DB structure, with the DB classified into forward flight and hover flight mode. Most of the aerodynamic data were obtained using rapid analysis tools that reduced the time costs. The accuracy and feasibility of the aerodynamic DB were evaluated by comparing the results of RANS-based computational fluid dynamics using the sliding mesh method and moving reference frame. In addition, based on this comparison, the need to improve the aerodynamic database was reviewed and discussed. - COLLAPSE
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CONSTRUCTION AND EVALUATION OF AERODYNAMIC DATABASE FOR UAM FLIGHT SIMULATOR INTEGRATIONPART Ⅰ: LIFT-CRUISE TYPE
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Research Article
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CONSTRUCTION AND EVALUATION OF AERODYNAMIC DATABASE FOR UAM FLIGHT SIMULATOR INTEGRATIONPART Ⅱ : MULTICOPTER TYPE
UAM 비행 시뮬레이터 탑재용 공력 데이터베이스 구축 및 평가Part Ⅱ : 멀티콥터형
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D.H. Kim, M.S. Tai, W.S. Lee, D.J. Lim, D.H. Park
김다혜, 태명식, 이우승, 임대진, 박동훈
- For urban air mobility(UAM) technology to be commercialized, it is necessary to utilize flight simulators to evaluate the stability and operational feasibility …
- For urban air mobility(UAM) technology to be commercialized, it is necessary to utilize flight simulators to evaluate the stability and operational feasibility of UAM aircraft under various urban scenarios and environmental conditions. This study presents the construction of an aerodynamic database(DB) of multicopter type UAM aircraft for flight simulator application based on the component build-up method and time-efficient aerodynamic analysis method. The aerodynamic DB consists of an airframe DB and a propeller DB, and is also divided into hovering mode and forward flight mode according to the aircraft operating conditions for efficient data generation and construction. The aerodynamic data of the airframe DB were obtained using RANS-based computational fluid dynamics, and the propeller performance data were obtained using a rapid analysis tool based on blade element momentum theory. The reliability and feasibility of the aerodynamic database were evaluated for several flight conditions by comparing it with the results of high-fidelity computational analysis for the full configuration. - COLLAPSE
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CONSTRUCTION AND EVALUATION OF AERODYNAMIC DATABASE FOR UAM FLIGHT SIMULATOR INTEGRATIONPART Ⅱ : MULTICOPTER TYPE
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Research Article
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OPTIMIZED BIOMIMETIC TRAILING EDGE FOR IMPELLER IN A CENTRIFUGAL PUMP: EFFECTS OF INFLOW
원심 펌프 임펠러의 생체모방공학 기반 최적화 연구: 입구 유동 조건의 영향
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C. Oh, J. Kim, S. Kang
오창종, 김조현, 강성원
- We aim at analyzing the mechanism of passive flow control by a biomimetic tubercle shape for impeller trailing edge(TE) in a centrifugal …
- We aim at analyzing the mechanism of passive flow control by a biomimetic tubercle shape for impeller trailing edge(TE) in a centrifugal pump and the effect of inflow conditions. A shape optimization process of tubercle heights was performed for two different inflow conditions that approximate the conditions of a three-stage centrifugal pump. The composite efficiency of the pump increased by up to 0.77%. Compared to the streamwise periodic condition, the inflow-outflow condition showed larger increase in the pump efficiency and decrease of the turbulent intensity. Among different tubercles along TE, a specific tubercle had a relatively large effect on the results. Vortex structures were examined using the Q-criterion and swirling strength. It was observed that the orientation of the vortices behind TE changed from spanwise to streamwise by the tubercle TE. Counter-rotating streamwise vortices were generated at the top and bottom of each tubercle, and the interaction of the vortex pair led to vortex breakdown, resulting in a decrease in the turbulent intensity. - COLLAPSE
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OPTIMIZED BIOMIMETIC TRAILING EDGE FOR IMPELLER IN A CENTRIFUGAL PUMP: EFFECTS OF INFLOW
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Research Article
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SHOCK PREDICTION USING ATTENTION BASED EXPLAINABLE DEEP NEURAL NETWORK
어텐션 기반의 설명가능한 신경망을 사용한 충격파 예측
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S. Kim, Y. Hong, S. Lee
김성현, 홍윤표, 이상아
- As artificial intelligence (AI) technology gains popularity, interest in using AI as a new method is also growing in the field of …
- As artificial intelligence (AI) technology gains popularity, interest in using AI as a new method is also growing in the field of aerodynamics. However, AI models based on deep neural networks have the drawback of being difficult to understand in terms of their internal mechanisms. Consequently, there has been an increase in attempts to interpret AI models using explainable artificial intelligence (XAI) technique. This study focuses on ensuring the reliability of AI models when applied to aerodynamic problems. To achieve this, attention-based XAI was utilized to predict shock waves on airfoils. Also, to enhance the fidelity and stability of the attention mechanism, multi-head attention method using attention in parallel was employed. Additionally, a new metrices based on entropy were proposed to evaluate the fidelity and stability of XAI. This demonstrated that the application of multi-head attention improved the performance of XAI. - COLLAPSE
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SHOCK PREDICTION USING ATTENTION BASED EXPLAINABLE DEEP NEURAL NETWORK
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Research Article
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DESIGN OF FORWARD-CURVED BLADE FOR CENTRIFUGAL FAN USING MESH MORPHING METHOD
Mesh morphing 기법을 활용한 전향익 원심팬 블레이드 형상 설계
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S. Park, J.T. Kim, J.S. Yang, J.K. Min
박성호, 김정태, 양재성, 민준기
- In this study, the rotor blade geometry of proposed forward-curved centrifugal fan was designed considering two performance metrics: aerodynamic efficiency and aeroacoustic …
- In this study, the rotor blade geometry of proposed forward-curved centrifugal fan was designed considering two performance metrics: aerodynamic efficiency and aeroacoustic noise. Baseline rotor blade geometry was modeled in two-dimensional domain with periodic boundary conditions. For optimal design of the rotor blade, the mesh morphing method which enables variable shapes was introduced with Simplex algorithm. Among the designing process, noise generated by rotation of the rotor blade has been predicted with turbulent viscosity. Derived three different blade geometries with mesh morphing method were further investigated with three dimensional calculation to reflect the effects by volute scroll and bellmouth geometry. The results made with different objective functions have been compared and assessed in quantitative and qualitative ways. - COLLAPSE
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DESIGN OF FORWARD-CURVED BLADE FOR CENTRIFUGAL FAN USING MESH MORPHING METHOD
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Research Article
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EXPERIMENTAL AND COMPUTATIONAL ANALYSIS OF LOADS ACTING ON A FIXED CIRCULAR CYLINDER UNDER WAVE CONDITIONS FOR THE DEVELOPMENT OF A VIRTUAL OCEAN BASIN
가상해양수조의 개발을 위한 파랑 중 고정된 원형 실린더에 작용하는 하중에 관한 모형시험 및 CFD 해석
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J. Park, C. Lee, W. Seok
박준영, 이창훈, 석우찬
- In this study, the wave loads acting on a circular cylinder under various wave conditions were analyzed using a towing tank at …
- In this study, the wave loads acting on a circular cylinder under various wave conditions were analyzed using a towing tank at Pukyong National University. For this analysis, the computational domain was modeled to match the towing tank, and CFD simulations were conducted using OpenFOAM. Additionally, the Morison equation was employed for an analytic solution. The comparison of wave load results from model tests, CFD simulations, and the Morison equation showed good agreement. Furthermore, the CFD simulations were also performed under conditions of high wave steepness to observe the physical phenomena of wave run-up and wave scattering, and the results were analyzed both qualitatively and quantitatively. - COLLAPSE
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EXPERIMENTAL AND COMPUTATIONAL ANALYSIS OF LOADS ACTING ON A FIXED CIRCULAR CYLINDER UNDER WAVE CONDITIONS FOR THE DEVELOPMENT OF A VIRTUAL OCEAN BASIN
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Research Article
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ROUGHNESS EFFECTS ON UNSTEADY PARTIAL CAVITATION FLOW AROUND NACA66 HYDROFOIL USING THE LES MODEL
LES 모델을 이용한 NACA66 수중익 주변의 비정상 부분 캐비테이션유동에 대한 거칠기 효과
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V. Karthik, J.C. Lee
KarthikVadivelu, 이장창
- The wall roughness effects on unsteady unstable partial cavitation flow around NACA66 hydrofoil are numerically investigated using the Schnerr-Sauer cavitation model with …
- The wall roughness effects on unsteady unstable partial cavitation flow around NACA66 hydrofoil are numerically investigated using the Schnerr-Sauer cavitation model with the LES turbulence model. The wall roughness in the LES is modeled with Harmonic Blending wall functions based on the roughness Reynolds number. The roughness is applied to the three different zones of the suction side of the hydrofoil with different heights according to the non-dimensional roughness height. The numerical results show the correlations between the roughness effects and cavity behavior. The increased surface roughness leads to higher turbulent velocity. The turbulence destabilizes the sheet cavitation, leading to more rapid cavitation collapse or shedding. As a result, increased roughness surface leads to higher shedding frequency. - COLLAPSE
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ROUGHNESS EFFECTS ON UNSTEADY PARTIAL CAVITATION FLOW AROUND NACA66 HYDROFOIL USING THE LES MODEL
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Research Article
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FLOW ANALYSIS FOR IRRIGATION AND SUCTION VALVES
세척/흡입 밸브 유동해석
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Y.-I. Kim, S.R. Kim
김영일, 김사량
- In order to develop a valve for a laparoscopic surgical irrigation/suction device, three shapes of valve were designed, and CDF analysis was …
- In order to develop a valve for a laparoscopic surgical irrigation/suction device, three shapes of valve were designed, and CDF analysis was performed on each design shape to get the relation between flow rate and pressure drop to determine the best shape. Steady-state incompressible flow analysis was performed using the Fluent s/w, and the Realizable turbulence model and standard wall function were used for turbulent flow analysis. We were able to develop a valve that is easy on the fingers and can replace the existing tube compression valve. - COLLAPSE
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FLOW ANALYSIS FOR IRRIGATION AND SUCTION VALVES
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Research Article
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NUMERICAL STUDY ON MASS TRANSFER AND HYDROGEN BUBBLE GENERATION IN WATER ELECTROLYSIS
수전해에서 물질 전달과 수소 기포 생성에 대한 수치적 연구
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J. Park, G. Son
박정주, 손기헌
- In alkaline water electrolysis(AWE), hydrogen bubbles are generated through electrochemical reactions involving the interaction between continuous and dispersed phases. In this work, …
- In alkaline water electrolysis(AWE), hydrogen bubbles are generated through electrochemical reactions involving the interaction between continuous and dispersed phases. In this work, a multiphase numerical model for AWE is developed to simulate the evolution of hydrogen bubble associated with the transport of dissolved hydrogen in liquid water. The numerical results show that bubble nucleation under supersaturation conditions of dissolved hydrogen gas is a critical parameter in determining gas evolution in AWE. The effects of ambient temperature and current density on bubble evolution are investigated. As current density increases and bubble resistance rises, the ohmic overpotential is observed to dominate over the activation overpotential. - COLLAPSE
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NUMERICAL STUDY ON MASS TRANSFER AND HYDROGEN BUBBLE GENERATION IN WATER ELECTROLYSIS
Journal Informaiton
Journal of Computational Fluids Engineering
Journal of Computational Fluids Engineering
Korean Society for Computational Fluids Engineering
한국전산유체공학회
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Tel: 82-2-701-8992 / E-mail: kscfe@kscfe.or.kr Copyright© Korean Society for Computational Fluids Engineering. Powered by APUB
Tel: 82-2-701-8992 / E-mail: kscfe@kscfe.or.kr Copyright© Korean Society for Computational Fluids Engineering. Powered by APUB