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Multi-Objective Optimization of an Axial Compressor Blade
김광용,Abdus Samad 대한기계학회 2008 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.22 No.5
Numerical optimization with multiple objectives is carried out for design of an axial compressor blade. Two conflicting objectives, total pressure ratio and adiabatic efficiency, are optimized with three design variables concerning sweep, lean and skew of blade stacking line. Single objective optimizations have been also performed. At the data points generated by D-optimal design, the objectives are calculated by three-dimensional Reynolds-averaged Navier-Stokes analysis. A second-order polynomial based response surface model is generated, and the optimal point is searched by sequential quadratic programming method for single objective optimization. Elitist non-dominated sorting of genetic algorithm (NSGA-II) with ε-constraint local search strategy is used for multi-objective optimization. Both objective function values are found to be improved as compared to the reference one by multi-objective optimization. The flow analysis results show the mechanism for the improvement of blade performance.
김광용,David J. Garbary 한국조류학회I 2009 ALGAE Vol.24 No.2
Imaging-PAM fluorometry was used to assess the chlorophyll a fluorescence parameter ΦPSII (effective quantum yield) in Fucus vesiculosus, F. distichus ssp. distichus and Ascophyllum nodosum. The objective was to show variation in fluorescence yield associated with age and frond organ, and to illustrate the spatial scales at which photosynthetic parameters vary on fucoid thalli. In addition, our species represented taxa in different but related genera, species with different ecologies (rock pool and non rock pool species), morphologies (with and without air bladders) and longevities (several to 20 or more years). A further objective was to determine the extent to which photosynthetic parameters reflected these differences. Effective quantum yield declined substantially with age in F. vesiculosus and F. distichus ssp. distichus, whereas ΦPSII in A. nodosum was maximal after three years. In A. nodosum ΦPSII was still high in branch segments at least seven years old. Older branches of A. nodosum showed relatively higher and more homogeneous photosynthetic capacity relative to Fucus species. Surfaces of air bladders in A. nodosum and F. vesiculosus had ΦPSII that was not significantly different from the highest rates achieved in these species. The heterogeneity of photosynthetic efficiency is consistent with morphological and developmental differences among the species and their ecology, in particular the longevity of A. nodosum fronds.
김광용,김진혁,허만웅,차경훈,탁세완,조용,황재천,Maria Collins 한국유체기계학회 2012 International journal of fluid machinery and syste Vol.5 No.4
A numerical study to investigate the effect of intake vortex occurrence on the performance of an axial hydraulic turbine for generating tidal power energy in Sihwa-lake tidal power plant, Korea, is performed. Numerical analysis of the flow through an axial hydraulic turbine is carried out by solving three-dimensional Reynolds-averaged Navier-Stokes equations with the shear stress transport turbulence model. In the real turbine operation, the vortex flows are occurred in both the side corners around the intake of an axial hydraulic turbine due to the interaction between the inflow angle of water and intake structure. To analyze these vortex phenomena and to evaluate their impacts on the turbine performance, the internal flow fields of the axial hydraulic turbines with the different inflow angles are compared with their performances. As the results of numerical analysis, the vortex flows do not directly affect the turbine performance.