• 한국추진공학회지
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• 제22권5호
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• pp.1-12
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• 2018

유선곡률해석법은 다단 축류 터빈의 설계과정에서 필수적으로 이용되며, 실제 작동환경에서 발생하는 손실을 설계 단계에서 미리 반영할 수 있다는 장점이 있다. 하지만 이와 관련한 국내 독자 연구가 부족한 실정이다. 본 연구에서는 다단 축류 터빈에서의 누설 유동에 따른 성능해석을 위해 유선곡률해석법과 유동 혼합에 따른 손실 예측 모델을 적용하였다. 국내 운전 중인 86 MW급 발전용 가스터빈의 5단 축류터빈에 대해 본 연구에서 제안한 방법을 적용하여 성능해석을 수행하였다. 계산된 결과는 3차원 전산해석 결과와 비교하였으며, 유선곡률해석법이 가지는 장점과 한계에 대해 기술하였다.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 1996년도 봄 학술발표회 논문집
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• pp.54-61
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• 1996

This paper deals with finite element analysis for incompressible viscous flow problem By formulating the governing equation based on the streamline upwind concept , the wiggle phenomenon of fluid flow is minimized in spite of a few number of finite element used. The penalty function method which can reduce the number of independent variables is adopted for the purpose of computational efficiency and the selected reduced integral is carried out for the convection and pressure terms to reserve the stability of solution. In time-history analysis of fluid flow, the accuracy and reliability of an obtained solution are established by using the predictor-corrector method. Finally, correlation studies between analytical and experimental results are conducted wi th the object ive to establish the validity of the proposed numerical approach.

• 대한기계학회논문집
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• 제19권10호
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• pp.2667-2677
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• 1995

A new numerical algorithm using equal order linear finite element and fractional step method has been developed which is capable of analyzing unsteady fluid flow and heat transfer problems. Streamline Upwind Petrov-Galerkin (SUPG) method is used for the weighted residual formulation of the Navier-Stokes equations. It is shown that fractional step method, in which pressure term is splitted from the momentum equation, reduces computer memory and computing time. In addition, since pressure equation is derived without any approximation procedure unlike in the previously developed SIMPLE algorithm based FEM codes, the present numerical algorithm gives more accurate results than them. The present algorithm has been applied preferentially to the well known bench mark problems associated with steady flow and heat transfer, and proves to be more efficient and accurate.

• 동력기계공학회지
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• 제3권3호
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• pp.54-59
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• 1999

The purpose of the present study was to develop the numerical method for predicting the on-design and off-design performance of multistage axial-flow compressors. The aerodynamic properties in blade rows were analyzed by incorporating the streamline curvature method as a quasi 3D analysis with the imperical modeling of exit flow angle and loss coefficients. The present calculation procedure has been tested by applying to 5-stage compressors and good agreement with experiments has been found. The detail analysis of aerodynamic performances has been done on the compression part of the bench-scaled gas turbine engines. The predicted performance map at the variable speedline and flow rates could be used as a guide of the engine operation.

• 한국물환경학회지
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• 제20권6호
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• pp.676-684
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• 2004

Many researchers have been carrying on study to figure out the exact collision efficiency between bubble and floc. Collision efficiency can has generally been quantified by using trajectory analysis which uses the hydrodynamic, the electrostatic and van der waals forces. Two types of method are considered to induce the hydrodynamic force in the trajectory analysis. One is to use stream function and the other is to use mobility function. There was some difference between stream and mobility function depending upon modelling factors and conditions in trajectory analysis.

• 대한조선학회논문집
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• 제42권3호
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• pp.290-298
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• 2005

A study of design and analysis for the POD type waterjet is conducted. The analysis and design of waterjet system are more difficult than that of conventional propulsor because waterjet is complicatedly composed of many parts which are impeller, stator, inlet, nozzle, etc. The streamline method is traditionally used in the design of pump whose characteristics are similar to those of waterjet. This streamline method, however, has some limitation in analysis of a viscous flow as well as the interaction of inlet part of hull. In the present study, the developed CFD program is applied to the analysis of POD type waterjet. The developed program is first validated by comparing the existed experimental results. The designed waterjet system is also analyzed by the developed CFD program and analyzed results show that the performance of the present POD type waterjet is above the requirement.

• 한국유체기계학회 논문집
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• 제6권2호
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• pp.41-46
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• 2003

The hydraulic design optimization and performance analysis of mixed-flow pumps for waterjet marine vehicle propulsion has been carried out using mean streamline analysis and three-dimensional computational fluid dynamics (CFD) code. In the present study, the conceptual design optimization has been formulated with a non-linear objective function to minimize the fluid dynamic losses, and then the commercial CFD code was incorporated to allow for detailed flow dynamic phenomena in the pump system. Newly designed mixed-flow model pump has been tested in the laboratory. Predicted performance curves by the CFD code agree very well with experimental data for a newly designed mixed-flow pump over the normal operating conditions. The design and prediction method presented herein can be used efficiently as a unified hydraulic design process of mired-flow pumps for waterjet marine vehicle propulsion.

• 유체기계공업학회:학술대회논문집
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• 유체기계공업학회 2000년도 유체기계 연구개발 발표회 논문집
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• pp.110-115
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• 2000

The mean streamline analysis using the empirical loss correlations has been developed for performance prediction of industrial mixed-flow fan impellers in the present study. New simple, but effective, models for the additional Euler input work characteristic and an internal recirculation loss due to internal flow reversal under the low flowrate conditions are proposed in this paper. Comparison of overall performance predictions with six sets of test data of mixed-flow fans is accomplished to demonstrate the accuracy of the proposed models. Predicted performance curves by the present set of loss models agree fairly well with experimental data for a variety of mixed-flow fan impellers over the entire operating conditions. The prediction method presented herein can be used efficiently in the conceptual design phase of mixed-flow fan impellers.

• Journal of Advanced Marine Engineering and Technology
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• 제23권2호
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• pp.216-225
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• 1999

Four turbulent $k-{varepsilon}$models(i.e standard model modified models with streamline curvature modification and/or preferential dissipation modification) are applied in order to analyze the tur-bulent flow of wall-attaching offset jet. The upwind numerical scheme was adopted in the present analyses. The streamline curvature modification results in slightly better prediction while the preferential dissipation modification does not. The obtained analytic results will be used as refer-ences for further study regarding Reynolds stress model. In addition this paper introduced a method of increasing nozzle outlet velocity gradually for numercal convergence. Even though the method was simple it was efficient in view of convergent speed CPU running time computer memory storage programming etc.

• 한국유체기계학회 논문집
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• 제6권1호
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• pp.30-36
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• 2003

This paper presents the analysis of flows through three different types of radial compressor impeller by using quasi-three-dimensional analysis method. The method obtains two-dimensional solution for velocity distribution on meridional plane, and then calculates approximately the static pressure distributions on blade surfaces. Finite difference method is used for the solutions of governing equations. The compressors have low level compression-ratio and 12 straight radial blades with no backsweep. The results are compared with experimental data and the results of three-dimensional inviscid analysis with those by finite element method. It is found that the agreements with experimental data are good for the cases where viscous effects are not dominant.