익렬유동 해석 기술동향

백제현,Baek, Je-Hyeon 재료연구소 1995 機械와 材料 Vol.7 No.3

스마트 IoT 안전모를 활용한 승강기 작업자 안전성 향상 및 위험요소 분석

백제현(Je-Hyeon Baek),박건웅(Gun-Woong Park),이상민(Sang-Min Lee) 한국정보기술학회 2024 Proceedings of KIIT Conference Vol.2024 No.11

회전하는 정사각 단면 U자형 곡관 내부의 유동 발달에 관한 수치적 연구 (I) - 층류 유동

이공희,백제현,Lee, Gong-Hui,Baek, Je-Hyeon 대한기계학회 2002 대한기계학회논문집 Vol.26 No.1

The present study investigates in detail the combined effects of the Coriolis and centrifugal farce on the development of laminar flows in a square-sectioned U-bend rotating about an axis parallel to the center of bend curvature. When a viscous fluid flows through a rotating curved region, two types of secondary flow occur. One is caused by the Coriolis force due to the rotation of U-bend and the other by the centrifugal farce due to the curvature of U-bend. When the values of Rossby number and curvature ratio are large, the flow field in a rotating U-bend can be represented by two dimensionless parameters ; the Dean number K$\_$LC/=Re/√λ and a body ratio F=λ/Po. For positive rotation, where the rotation is in the same direction as that of the main flow, both the Coriolis force and the centrifugal force act radially outwards, the directions of the two secondary flows are the same. Therefore, the flow structure is qualitatively similar to that observed in a stationary curved duct with a larger f7c. On the other hand, in case of negative rotation, where two farces act in opposite direction, more complex flow fields can be observed depending on the relative magnitudes of the forces.

터보기계 익렬을 위한 격자 형성

정희택,백제현,Jeong, Hui-Taek,Baek, Je-Hyeon 한국기계연구원 1995 硏究論文集 Vol.25 No.-

A grid generation algorithm associated with turbomachinery cascade flow fields has been developed. The present grid generation system consists of four separate modules. The system input is made of the results of the preliminary design, i.e., flow-path, aerodynamic conditions along the spanwise direction, and the blade profile data. The grid generation method generates a series of two-dimensional grids in the blade-to-blade passage to build up the three-¬dimensional grid, The numerical algorithm adopts the combination of the algebraic and elliptic method to create the internal grids efficiently and quickly. The resultant grids generated from each module of the system are used as the preprocessor for the performance prediction of the turbomachinery blade using Naveir-Stokes method in addition to the blade surface modelling for CAD data. For purposes of illustration, the grid generation system is applied to several complex geometries inculding a turbine rotor with and without a tip flow grid. Application to the blade design of the LP compressor was demonstrated to be very reliable and practical in support of design activities. This customized system are coupled strongly with the design procedure and reduces the man-hours required to predict the aerodynamic performance of the turbomachinery cascades using the CFD technique.

수직축을 중심으로 회전하는 직관과 정지한 곡관내에서의 층류 유동의 유사성 비교

이공희,백제현,Lee, Gong-Hui,Baek, Je-Hyeon 대한기계학회 2000 大韓機械學會論文集B Vol.24 No.12

In this study, it is numerically revealed that the secondary flow due to the Coriolls force in a straight duct rotating about an axis perpendicular to that of the duct is analogous to that caused by the centrifugal force in a stationary curved duct. Dimensionless parameters $K_{LR}=Re/\sqrt{Ro}$ and Rossby number in a rotating straight duct were used as a set corresponding to Dean number and curvature ratio in a stationary curved duct. When the value of Rossby number and curvature ratio is large, it is shown that the flow field satisfies the `asymptotic invariance property`, that is, there are strong quantitative similarities between the two flows such as friction factors, flow patterns, and maximum axial velocity magnitudes for the same values of $K_{LR}$ and Dean number.

회전하는 정사각 단면 U자형 곡관 내부의 유동 발달에 관한 수치적 연구 (I) - 층류 유동

이공희,백제현,Lee, Gong-Hui,Baek, Je-Hyeon 대한기계학회 2002 大韓機械學會論文集B Vol.26 No.1

The present study investigates in detail the combined effects of the Coriolis and centrifugal farce on the development of laminar flows in a square-sectioned U-bend rotating about an axis parallel to the center of bend curvature. When a viscous fluid flows through a rotating curved region, two types of secondary flow occur. One is caused by the Coriolis force due to the rotation of U-bend and the other by the centrifugal farce due to the curvature of U-bend. When the values of Rossby number and curvature ratio are large, the flow field in a rotating U-bend can be represented by two dimensionless parameters ; the Dean number K$\_$LC/=Re/√λ and a body ratio F=λ/Po. For positive rotation, where the rotation is in the same direction as that of the main flow, both the Coriolis force and the centrifugal force act radially outwards, the directions of the two secondary flows are the same. Therefore, the flow structure is qualitatively similar to that observed in a stationary curved duct with a larger f7c. On the other hand, in case of negative rotation, where two farces act in opposite direction, more complex flow fields can be observed depending on the relative magnitudes of the forces.

축류 압축기내의 2차원 유동 특성

홍성훈,백제현,Hong, Seong-Hun,Baek, Je-Hyeon 대한기계학회 1996 大韓機械學會論文集B Vol.20 No.8

The flow in the turbomachinery is very unsteady due to the stator-rotor interaction. It has been indicated that the stator-rotor interaction has three distinct causes of unsteadiness: that is, the viscous vortex shedding, wake rotor interaction and potential stator-rotor interaction. In this paper, the mechanism of unsteady potential interaction and wake interaction in the stator-rotor stage flow is numerically investigated in two-dimensional view point. The numerical technique used is the upwind scheme of Van Leer's Flux Vector Splitting(FVS) and cubic spline interpolation is applied on zonal interface. Then, the flow field of a compressor stage composed of NACA 65410 is analyzed. Flow fields are found to be simulated reasonably by this method and the sensitivity due to back-pressure variation is more stronger than rotor-velocity variation.

고속전철 시스템의 공기역학적 특성

손정락,이동호,백제현,모규경,Son, Jeong-Rak,Lee, Dong-Ho,Baek, Je-Hyeon,Mo, Gyu-Gyeong 재료연구소 1991 機械와 材料 Vol.3 No.3

V2-F 난류 모델의 터보기계 유동 해석 적용

박재현(Jae Hyeon Park),손동경(Dong Kyung Sohn),김창현(Chang Hyun Kim),백제현(Je Hyun Baek) 대한기계학회 2016 大韓機械學會論文集B Vol.40 No.2

터보기계 내부 유동장은 역압력구배, 고속 유동으로 인해 매우 복잡하며, 이를 해석하기 위해 보다 정교한 난류 모델이 요구된다. 유동 해석을 위해 대수모델, 2-방정식 와점도 모델 등이 널리 사용되고 있으나, 매우 복잡한 유동을 모사하는데 어려움이 있다. 본 연구에서는 복잡한 유동에서의 예측성능이 우수하다고 알려진 Durbin의 V2-F 난류 모델을 자체 개발 코드인 T-Flow에 적용하였으며, 채널 및 압축기 캐스캐이드 유동 해석 결과를 이용하여 난류 모델을 검증하였다. 또한 저속 압축기 동익 해석을 통해 터보기계 내부 유동에서의 적용 가능성을 판단하였다. 그 결과, V2-F난류 모델은 1-방정식, 2방정식 난류 모델보다 우수한 블레이드 표면 압력 분포 예측성능을 보였다. Since a turbomachine has complex flow characteristics, which are caused by adverse pressure gradient and high speed motion, an elaborate turbulence model is needed to accurately predict the flow. Some turbulence models such as an algebraic or a two-equation eddy viscosity model have been used for in-house RANS-code, but it is difficult to obtain good result for several complex flows. In this study, Durbin‘s V2-F turbulence model, which has been known for better prediction for severe flow separation, is applied to T-Flow. It was validated for simple cases such as channel and compressor cascade, and its applicability to turbomachinery was shown by analyzing internal flow of a single rotor. As a result, the V2-F turbulence model shows better blade surface pressure distribution than the one-and-two equation turbulence model.

승강로를 활용한 침수 재난 대비 스마트센싱 원격 시스템

박건웅(Gun-Woong Park),백제현(Je-Hyeon Baek),이유선(Yu-Sun Lee),이상민(Sang-Min Lee) 한국정보기술학회 2024 Proceedings of KIIT Conference Vol.2024 No.5

최근 도시지역 내 증가하는 침수 사고를 방지하기 위해, 2023년 9월 <도시하천유역 침수 피해 방지 대책법>이 도입되었다. 과거 서울시의 개발은 침수 및 방수 대책 없이 저지대에 집중되어 시가지가 조성되었고, 그 결과 현재까지 지속적인 침수 문제를 낳고 있다. 특히 지하층과 주차장의 침수는 종종 고립 사고로 이어져 인명피해가 발생한다. 현재 침수 피해 최소화를 위해 시장에 나와 있는 제품들은 불투수면이 많고 수위가 제품의 높이를 초과하는 경우 효과가 제한적이다. 본 연구는 건물 최하층과 주차장에 갇힌 사람들을 구조하기 위해 승강기 승강로를 이용한 원격 인명구조 시스템을 제안한다. 이 시스템은 단일 보드 마이크로컨트롤러를 사용한 프로토타입으로 개발되었으며, 침수 환경을 감지하고 대응하는 기능 구현을 목표로 한다. Recently, to combat the rise in flood incidents within urban areas, the Urban Stream Basin Flood Damage Prevention Act was enacted in September 2023. Historical development in Seoul concentrated on low-lying areas without flood or waterproofing measures, leading to ongoing flooding problems. Floods in basements and parking lots often result in isolation incidents, leading to casualties. The effectiveness of current market solutions for minimizing flood damage is limited in areas with high impermeability and when water levels exceed product heights. This study introduces a remote human rescue system using elevator shafts to assist individuals trapped in the lowest floors and parking lots of buildings. The system, developed as a prototype using a single-board microcontroller, aims to detect and respond to flooding conditions.