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Original Article
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NUMERICAL ANALYSIS OF UNSTEADY CAVITATING FLOW AND NOISE CHARACTERISTICS OF A 2D HYDROFOIL
2차원 수중익의 비정상 공동 유동 및 유기 소음 특성 규명을 위한 수치해석
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N.U. Heo, J.H. Kim
허남욱, 김지혜
- Due to the adverse impact of induced noise generated from ships on the marine ecosystem, there has been a gradual strengthening of …
- Due to the adverse impact of induced noise generated from ships on the marine ecosystem, there has been a gradual strengthening of international environmental regulations aimed at suppressing it. Specially, cavitation occurring in marine propellers is a major source of ship noise, making it necessary to understand the development and noise characteristics of cavitation of it. In this study, we are focusing our attention on investigating the occurrence and noise characteristics of cavitation around 2D hydrofoils using commercial program, STAR-CCM+. Additionally, the noise characteristics of cavitation are examined by conducting frequency analysis of fluctuating pressure at a vertical position above the hydrofoil and the numerical results are validated by comparison with existing experimental data. - COLLAPSE
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NUMERICAL ANALYSIS OF UNSTEADY CAVITATING FLOW AND NOISE CHARACTERISTICS OF A 2D HYDROFOIL
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Original Article
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THE EFFECT OF INLET FLUE GAS PATTERN ON THE PERFORMANCE PREDICTION OF DeNOx SYSTEM USING CFD METHODS
탈질 시스템의 성능 예측에서의 유입 배기가스의 형태 영향에 대한 CFD 해석
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M.K. Kim, H.T. Chung
김민규, 정희택
- In the present study, the effect of the flow pattern of the inlet flue gas were investigated on the denutrification performance through …
- In the present study, the effect of the flow pattern of the inlet flue gas were investigated on the denutrification performance through the numerical simulation. As the examples of the off-design conditions, the skewed and double parabolic flow were chosen to compare the uniform flow used as the design condition. The SCR type of DeNOx facilities of the large-scaled coal-fired power plant currently in operation were adopted as the application model. In order to to deduce three performance variables, the steady two-dimensional turbulent flow were solved using the thermal-flow software named as ANSYS-Fluent. Comparing the off-design conditions to the design condition, the computational results showed that the predicted performances differed by 15.6% for the flow uniformity, 127% for NH3/NO molar ratio of the mixed gas and 10.2% for the pressure loss of the whole process. - COLLAPSE
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THE EFFECT OF INLET FLUE GAS PATTERN ON THE PERFORMANCE PREDICTION OF DeNOx SYSTEM USING CFD METHODS
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Original Article
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NUMERICAL PREDICTION OF AERODYNAMIC NOISE OF LEAKAGE FLOW USING CFD/CAA HYBRID METHOD
CFD/CAA 연계 해석을 이용한 누설 유동의 공력 소음 예측
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S.U. Kang, S.J. Kim, P.S. Ma, Y.H. Seo, R.S. Myong, H. Lee
강성우, 김시진, 마평식, 서윤호, 명노신, 이학진
- The high speed flow leaked from cracks in gas pipelines can lead to severe explosion accidents. Therefore, detecting the location of leakage …
- The high speed flow leaked from cracks in gas pipelines can lead to severe explosion accidents. Therefore, detecting the location of leakage flow early and precisely is important to reduce the damage from leakage flow. The three-dimensional probe array using the acoustic intensity signals is one of the useful leak detection technologies. In this study, the CFD/CAA hybrid method is used to investigate the flow and acoustic characteristics of leakage flow. The features of leakage flow, including turbulence scales, roll-up phenomenon, strong shock waves, and Mach disk are predicted through the large eddy simulation (LES), and the far-field noise is calculated using the Ffowcs Williams-Hawkings (FW-H) acoustic analogy with permeable surfaces. The parametric study is performed in terms of the internal pressure condition in the pipe (10, 30, 50, 100 bar) and the size of leakage hole (5, 8, 10 mm) to analyze the flow and acoustics characteristics of the leakage flow. The strong Mack disk expands widely as the internal pressure and hole size increase while screech tone noise at specific frequency is observed as the internal pressure and hole size decrease. It turns out that overall sound pressure level (OASPL) of leakage flow increases about 15 dB when screech tone noise occurs. - COLLAPSE
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NUMERICAL PREDICTION OF AERODYNAMIC NOISE OF LEAKAGE FLOW USING CFD/CAA HYBRID METHOD
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Original Article
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NUMERICAL INVESTIGATION OF FLOW ENTERING THE TOP OF THE WAFER IN SINGLE-WAFER WET CLEANER
단일-웨이퍼 습식 세정 장비에서 웨이퍼 상부로 들어오는 유동의 수치해석
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S.H. Park, C. Lee
박시현, 이창훈
- This study investigates factors contributing to process defects in the single wafer wet cleaner equipment used for semiconductor wet cleaning processes. For …
- This study investigates factors contributing to process defects in the single wafer wet cleaner equipment used for semiconductor wet cleaning processes. For a possible cause of defects in the cleaning process, we suspect the presence of a radially inward flow during the drying step where the cleaning process is completed. We explore the complex flow characteristics of the rotational structure to investigate the backflow in the radial direction. The wafer rotation structure, with a disk-shaped coaxial design, induces radial backflow on the wafer side. On the other hand, when a guide structure is present, backflow occurs along the guide, and it was observed that the flow through the guide structure increases with an increase in exhaust pressure. Backflow through the lower part of the guide, influenced by the vortex generated by exhaust pressure and guide, was identified. We propose a method to improve backflow by adjusting the position of the guide edge to enhance the inflow through the guide's upper part. - COLLAPSE
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NUMERICAL INVESTIGATION OF FLOW ENTERING THE TOP OF THE WAFER IN SINGLE-WAFER WET CLEANER
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Original Article
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NUMERICAL STUDY ON IMPROVEMENT OF THE COOLING FAN PERFORMANCE FOR AN INDUCTION MOTOR
유도 전동기 냉각 팬 성능 향상에 관한 수치적 연구
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Y. Na, S. Yang, G. Son
나유창, 양성진, 손기헌
- Increasing motor efficiency is becoming more important as efficiency regulations for induction motors, which account for about 40% of global power consumption, …
- Increasing motor efficiency is becoming more important as efficiency regulations for induction motors, which account for about 40% of global power consumption, are strengthened. However, research on reducing mechanical losses by improving the performance of external cooling fan is still lacking in the literacture. In this work, to find a way to minimize fan power consumption while maintaining the original fan flow rate, we investigated the influence of various parameters such as number of blades, blade height, blade angle, and fan cover shape on fan performance through three-dimsnional numerical simulations. The present computations show that power consumption can be improved by changing the blade angle and fan cover shape. - COLLAPSE
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NUMERICAL STUDY ON IMPROVEMENT OF THE COOLING FAN PERFORMANCE FOR AN INDUCTION MOTOR
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Original Article
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NUMERICAL ANALYSIS OF EFFECTS OF OPERATING CONDITIONS ON PURGING EFFICIENCY IN A VACUUM REGIME
저진공 영역에서 배관의 운전 조건에 따른 배관 퍼지 효과의 수치해석 연구
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T. Kim, H. Ahn, D. You
김태근, 안호진, 유동현
- Purging, the process of removing undesired or inert gases from a system, is of critical importance in various industries, including semiconductor manufacturing. …
- Purging, the process of removing undesired or inert gases from a system, is of critical importance in various industries, including semiconductor manufacturing. The ability to accurately model and simulate purging processes can enhance the design and optimization of purging systems, leading to improved efficiency, reduced costs, and enhanced safety. Simulation of purging and neutralization within the pipe was conducted to understand the phenomena. The simulation explored in a vacuum regime to find optimal purging conditions by varying pressure difference of pipe inlet and outlet, operating pressure, and wall temperatures. - COLLAPSE
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NUMERICAL ANALYSIS OF EFFECTS OF OPERATING CONDITIONS ON PURGING EFFICIENCY IN A VACUUM REGIME
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Original Article
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NUMERICAL STUDY OF THE REMOVAL PERFORMANCE OF THE OIL PEELING PROCESS ACCORDING TO THE SKIMMER STRUCTURE AND EXTERNAL VIBRATION
유회수기 구조와 외부 진동에 따른 기름 박리 과정의 제거 성능에 대한 수치 연구
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C. Lee, G. Choi, S.J. Kim, S. Shin
이채원, 최근혁, 김성진, 신승원
- With growing interests in the marine environment, endeavors aimed at reducing impact from pollutants are being increased. Fuel with lower sulfur acid …
- With growing interests in the marine environment, endeavors aimed at reducing impact from pollutants are being increased. Fuel with lower sulfur acid becomes popular since it can reduce pollutants with relatively low cost. However, this Low Sulfur Fuel Oil exhibits large viscosity at lower temperature as it tends to adhere strongly to oil recovery devices impeding the effectiveness of continuous oil removal. Recently, it has been proposed that hydrophilic surface treatment can increase the peeling performance of oil from surface. Our previous work was focused on identifying peeling mechanism acting on vertically dipping plate through numerical investigation. In this study, we are aiming to get insights for increased peeling performance from rachet structure since it can minimize contact between oil and the solid structure. At the same time, we also want to find out environmental effect from wave induced vibration in oceanic environment. The effect from wave amplitude, frequency, and direction will be studied in detail for both flat and ratchet geometries. It has been found that hydrophilic ratchet geometry is very effective for oil removal and the removal performance is enhanced by wave induced vibration contrary to the flat surface. - COLLAPSE
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NUMERICAL STUDY OF THE REMOVAL PERFORMANCE OF THE OIL PEELING PROCESS ACCORDING TO THE SKIMMER STRUCTURE AND EXTERNAL VIBRATION
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Original Article
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NUMERICAL STUDY OF UNSTEADY CAVITATION CHARACTERISTICS AROUND NACA66 HYDROFOIL USING LES MODEL
LES 모델을 이용한 NACA66 수중익 주위의 비정상 캐비테이션 특성에 대한 수치해석적 연구
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V. Karthik, J.C. Lee
Vadivelu Karthik, 이장창
- The presence of cavitation in hydraulic machinery leads to vibrations, noise, and a decrease in efficiency. The characteristics of unsteady partial cavitation …
- The presence of cavitation in hydraulic machinery leads to vibrations, noise, and a decrease in efficiency. The characteristics of unsteady partial cavitation around NACA66 hydrofoil are numerically investigated. The Schnerr-Sauer cavitation model which is based on two-phase Rayleigh-plesset equation (bubble transport equation) is applied with LES turbulence model. The stable cavitation characteristics affected by cavitation length are studied. In results, the contours of the the vortical structure, boundary layer separation, the re-entrant jet, and the transition from sheet cavitation to cloud cavitation are clearly shown. The numerical results are in good agreement with the experiment. - COLLAPSE
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NUMERICAL STUDY OF UNSTEADY CAVITATION CHARACTERISTICS AROUND NACA66 HYDROFOIL USING LES MODEL
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Original Article
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EFFECTS OF PHASE CHANGE FOR COMPRESSIBLE FLUID AND SOLID WALL REGION ON PULSATING HEAT PIPE IN COMPUTATIONAL ANALYSIS
전산 해석에서 압축성 작동유체의 상변화와 고체 벽 영역이 진동형 히트파이프에 미치는 영향
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M.J. Son, J.W. Choi
손민재, 최종욱
- In this study, the heat transfer processes including the phase change in the pulsating heat pipe were performed numerically. To make the …
- In this study, the heat transfer processes including the phase change in the pulsating heat pipe were performed numerically. To make the computational analysis, the OpenFOAM program was modified considering the compressible working fluid and the solid wall region. During the phase change process, the circulating liquid and vapor phases were visualized within the pulsating heat pipe. The effects of the compressible working fluid and the solid wall region on the pulsating heat pipe were investigated. The thermal resistance was obtained and compared with the experimental result. This study will make good use of the design and the analysis of pulsating heat pipes. - COLLAPSE
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EFFECTS OF PHASE CHANGE FOR COMPRESSIBLE FLUID AND SOLID WALL REGION ON PULSATING HEAT PIPE IN COMPUTATIONAL ANALYSIS
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Original Article
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REAL-TIME PERFORMANCE PREDICTION OF A PHYSICS-BASED PUMP SYSTEM SIMULATION USING BAYESIAN OPTIMIZATION
베이지안 최적화를 활용한 물리 기반 펌프 시스템 시뮬레이션의 실시간 성능 예측
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G. Kang, S. Kim, K. Cha, J.-H. Kim, M. Lee, J. Lee
강경혁, 김수현, 차경환, 김주한, 이명성, 이종수
- This study aims to develop a model designed to effectively respond to fluctuations in energy demand. It involves constructing a physics-based simulation …
- This study aims to develop a model designed to effectively respond to fluctuations in energy demand. It involves constructing a physics-based simulation capable of real-time performance prediction for a two-stage centrifugal pump system. The model is composed of Modelica and a Reduced-order Model(ROM). It predicts key performance indicators such as pump head and flow rate in real-time. Additionally, a multi-parameter calibration framework using Bayesian optimization was applied to reflect the actual performance of the pump. This framework calibrates the parameters of the Modelica model. As a result, the error rates for flow rate and head were reduced to 2.87% and 3.58%, respectively. - COLLAPSE
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REAL-TIME PERFORMANCE PREDICTION OF A PHYSICS-BASED PUMP SYSTEM SIMULATION USING BAYESIAN OPTIMIZATION
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