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4밸브엔진의 압축과정에서 거시적 유동구조에 관한 수치해석적 연구
백제현(J.H.Baek),정동수(D.s.Jung),강건용(K.Y.Kang),박민영(M.Y.Park) 한국자동차공학회 1994 한국자동차공학회 춘 추계 학술대회 논문집 Vol.1994 No.11_1
The three-dimensional code for simulation of in-cylinder flow in arbitrary engines has been developed and applied to the selected 4-vaJvc pant-roof-headed model engine. This code adapts a finite-volume method based on non-orthogonal moving coordinate formulation of governing equation with covariant velocity component. A k-ε turbulence model modified for compressibility is used to represent turbulent transport of momentum. Computations are performed from intake valve opening to compression TDC. Our principal interests are made in the intake-generated lage-scale flow structures, their break-up mechanism at late-compression and their influence on near-TDC flow structure and turbulence. Results for four kinds of inlet flow conditions are presented for various seat angles. Results show that appropriately-low seat angle of valve and definite orientation of inlet flow are favorable for formation of well-defined large-scale flow structures and converting mean flow energy into turbulence.
초소형 가스 터빈용 저널 베어링 내 유동장 수치해석을 통한 응답특성 분석
서준혁(J.H. Seo),백제현(J.H. Baek) 한국전산유체공학회 2011 한국전산유체공학회 학술대회논문집 Vol.2011 No.5
Since MEMS based micro actuators or generating devices have high efficiency per volume, plenty of research are ongoing. Among them, MEMS based millimeter-scale micro gas turbine is one of the most powerful issue for replacing chemical batteries. However, since limiting of MEMS manufacturing technique, it is very difficult that makes wide turbine bearing area. It causes low DN number, so sufficient bearing force is hard to achieve. Thus, the most important issue on micro gas turbine is proper bearing design which can keep rotor stable during operation. In order to that, micro-scale gas-lubricated bearing is generally used. In this paper, basic feasibility study and design of journal bearing for 10㎜ diameter micro gas turbine is described. Journal bearing is hydrostatic gas-lubricated type. Numerical simulation is performed with ANSYS CFX 11.0 which is commercial numerical tool. Repulsive force when there is radial displacement in bearing and returning time is calculated using steady and unsteady cases. Auto re-meshing technic is used for moving mesh unsteady cases which simulate displacement of axis and its movement. The simulation results are used for further design of micro gas turbine, and experiment will be done later.
초소형 가스 터빈용 스러스트 베어링 내의 유동특성 해석
서준혁(J.H. Seo),백제현(J.H. Baek) 한국전산유체공학회 2010 한국전산유체공학회 학술대회논문집 Vol.2010 No.5
Since MEMS based micro actuators or generating devices showed high efficiency per volume, plenty of research are ongoing. Among them, MEMS based millimeter-scale micro gas turbine is one of the most powerful item for replacing chemical batteries. However, due to MEMS manufacturing technique, it is very difficult that makes wide turbine bearing area. It causes low DN number, so sufficient bearing force is hard to achieve. Thus, the most important issue on micro gas turbine is to design the proper bearing which can keep rotor stable during operation. In order to that, micro-scale gas-lubricated bearing is generally used. In this paper, basic feasibility study of thrust bearing of 10mm diameter turbine is described. Thrust bearing is hydrostatic gas-lubricated type. Numerical simulation is performed with ANSYS CFX 11.0 which is commercial numerical tool. Relationship between bearing inlet pressure and mass flow rate and bearing force is figured while changing bearing gap and number of capillaries. The simulation results will be used for further design of micro gas turbine.
김창현(C.H. Kim),박재현(J.H. Park),고동건(D.G. Ko),김동일(D.I. Kim),김영상(Y.S. Kim),백제현(J.H. Baek) 한국전산유체공학회 2015 한국전산유체공학회지 Vol.20 No.3
When the steam is used as working fluid in fluid machinery, different from other gases as air, phase transition (steam condensation) can occur and it affects not only the flow fields, but also machine performance & efficiency. Therefore, considering phase transition phenomena in CFD calculation is required to achieve accurate prediction of steam flow and non-equilibrium wet-steam model is needed to simulate realistic steam condensing flow. In this research, non-equilibrium wet-steam model is implemented on in-house code(T-Flow), the flow fields including phase transition phenomena in convergent-divergent nozzle are studied and compared to results of advance researches.
단단 축류 터보기계의 유동해석을 위한 계산격자점 생성 프로그램의 개발 및 적용
정희택(H.T. Chung),박준영(J.Y. Park),백제현(J.H. Baek) 한국전산유체공학회 2000 한국전산유체공학회지 Vol.5 No.2
An integrated grid generation has been developed for a Navier-Stokes simulation of flow fields inside multistaged turbomachinery, The internal grids are generated by the combination of algebraic and elliptic methods. The interactive mode of the present system is coupled efficiently with the design results and flow solvers, Application to several types of axial-flow turbomachines was demonstrated to be reliable and practical as the pre-processor of the computational fluid engineering for gas turbine engines.
축류터빈 블레이드의 공력학적 설계를 위한 Navier-Stokes방정식의 적용
정희택(H.T. Chung),정기섭(K.S. Chung),박준영(J.Y. Park),백제현(J.H. Baek),장범익(B.I. Chang),조수용(S.Y. Cho) 한국전산유체공학회 2003 한국전산유체공학회지 Vol.8 No.4
The design method for transonic turbine blades has been developed based on Navier-Stokes equations. The present computing process is done on the four separate steps, I. e., determination of the blade profile, generation of the computational grids, cascade flow simulation and analysis of the computed results in the sense of the aerodynamic performance. The blade shapes are designed using the cubic polynomials under the control of the design parameters. Numerical methods for the flow equations are based on Van-Leer’s FVS with an upwind TVD scheme on the finite volume. In the present study, numerical simulation has been done to investigate the effects of the design parameters on the aerodynamic performance of the axial-flow turbine blades Applications are made to the VKI transonic rotor blades. Computed results are analyzed with respect to four parameters and compared with the experimental data.