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김양익(Yang-Ik Kim),정경남(Kyung-Nam Chung) 한국유체기계학회 2005 유체기계 연구개발 발표회 논문집 Vol.- No.-
In this study, redesign of a vaporizer sea-water pump has been carried out using computational fluid dynamics. The flow field of the specified pump model is simulated and analyzed. In the flow analysis full pump model has been used, and multi-block grids are employed to solve the governing equations. In order to improve pump efficiency, systematic redesign has been performed to remove the flow recirculation near the hub of the diffuser vanes. The modified model shows about 4 % improvement in pump efficiency compared to the given model.
정경남(Kyung-Nam Chung),김양익(Yang-Ik Kim),성주헌(Ju-Heon Sung),정인호(In-Ho Chung) 한국유체기계학회 2004 유체기계 연구개발 발표회 논문집 Vol.- No.-
In this study, a rotor blade of a Curtis turbine is investigated. Bezier curve is generally used to define the profile of turbine blades. However, this curve gives a feature of global control, which is not proper to a supersonic impulse turbine blade. Thus, a blade design method is developed by using B-spline curve so that local control is possible to obtain an optimized blade section. To design a Curtis turbine blade section systematically, the blade section has been changed by varying three design parameters using central composite design method. Flow analyses have been carried out for the blade sections, and the effects of design parameters are evaluated.
정경남(Kyung-Nam Chung),김양익(Yang-Ik Kim) 한국유체기계학회 2006 유체기계 연구개발 발표회 논문집 Vol.- No.-
In this study cavitation performance analysis has been carried out to predict the NPSH required value of the models of a vaporization sea-water pump. Rayleigh-Plesset equation is used to represent the generation and collapse of cavitation bubbles. Prior to study pump cavitation, cavitation phenomenon on a NACA 66 modified section has been reproduced, and the calculation result has been compared with experimental data. Impeller-only model and full pump model are employed to study the effects of inlet real geometry and diffuser vanes in pump cavitation analysis. It has been shown that a impeller-only model can be used to analyze vertical pump cavitation around the design point. The analysis shows that cavitation performance of the redesigned model of the vaporization sea-water pump is satisfactory.
박종후(Jong-Hwoo Park),정경남(Kyung-Nam Chung),김양익(Yang-Ik Kim),조성희(Seoung-Hee Cho) 한국유체기계학회 2006 유체기계 연구개발 발표회 논문집 Vol.- No.-
A steam turbine is one of propulsion systems of a LNG carrier, which consists of high pressure (HP) and low pressure (LP) turbines. In order to obtain high power, each one has the form of a multi-stage turbine. Especially, the first stage of a HP turbine is Curtis stage and uses partial admission considering the turbine efficiency. The performance of a HP turbine can be predicted by a mean-line analysis method, because the relatively large value of hub-tip ratio makes the three-dimensional losses small. In this study, a performance analysis method is developed for a multi-stage HP turbine using Chen’s loss model developed for the transonic steam turbines. To consider the feature of partial admission, different partial admission models are reviewed. This analysis method can be used in partial load conditions as well as full load condition. The calculation results are also compared with the CFD results about some simple cases to check the accuracy of the program. Performance of two HP turbine models are calculated, and the calculation results are compared with the designed data. The comparison shows the qualitative performance analysis result.