• Journal of Advanced Marine Engineering and Technology
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• v.32 no.6
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• pp.827-833
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• 2008

In this study, mathematical expressions based upon the conventional BEMT(blade element momentum theory) was applied to basic 100kW wind turbine blade configuration design. Power coefficient and related flow parameters, such as Prandtl's tip loss coefficient, tangential and axial flow induction factors of the wind turbine were analyzed systematically. X-FOIL was used to acquire lift and drag coefficients of the 2-D airfoils and Viterna-Corrigan formula was used o interpolate he aerodynamic characteristics in post-stall region. Also, aerodynamic characteristics, measured in a wind tunnel to calculate he power coefficient was applied. The comparative results such as axial and tangential flow factors, power coefficients were presented in this study. Power coefficient, calculated by in-house code was compared with the GH-Bladed result. The difference of the aerodynamic characteristics caused the difference of the performance characteristics as variation as TSR.

• International Journal of Naval Architecture and Ocean Engineering
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• v.10 no.4
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• pp.477-490
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• 2018

Effects of inflow Reynolds number (Re), turbulence intensity (I) and pressure gradient on the transition flow over a blade section were studied using the ${\gamma}-Re{\theta}$ transition model (STAR-CCM+). Results show that the $Re_T$ (transition Re) at the transition location ($P_T$) varies strongly with Re, I and the magnitude of pressure gradient. The $Re_T$ increases significantly with the increase of the magnitude of favorable pressure gradient. It demonstrates that the $Re_T$ on different blade sections of a rotating propeller are different. More importantly, when there is strong adverse pressure gradient, the $P_T$ is always close to the minimum pressure point. Based on these conclusions, the $P_T$ on model propeller blade surface can be estimated. Numerical investigations of pressure distribution and transition flow on a propeller blade section prove these findings. Last, a simple method was proposed to estimate the $P_T$ only based on the propeller geometry and the advance coefficient.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2001.11a
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• pp.11-14
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• 2001

3-D compressible flow analysis was conducted by using mixing plane method for turbine system which is consisted of partial admission nozzle and rotor. Computational results are shown oblique shock wave in blade leading and trailing edge and also shown flow separation along suction surface of blade due to abrupt blade curvature. But computational results are well agree with 1-D calculation results and experimental data.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.26 no.11
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• pp.1552-1558
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• 2002

The blade leading edge is modified to control the secondary flow generated in the turbine cascade with fence by intensifying the suction side branch of the horseshoe vortex. The incompressible Navier-Stokes equations are numerically solved with a high Reynolds number k-$\varepsilon$ turbulence closure model for investigating the vortical flows in the turbine cascade. The computational results of total pressure loss coefficients in the wake region are first compared with experiments for validation. The structure and strength of the passage vortex near the suction surface are examined by testing various geometrical parameters of the turbine blade leading edge.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2001.05a
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• pp.69-74
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• 2001

The Wells turbine has hysteresis characteristics in a reciprocating flow. In this paper, in order to understand unsteady flow characteristics of the Wells turbine, a sinusoidal flow condition is simulated. The flow conditions and hysteresis characteristics, including blade thickness, are investigated over a period of time. The pressure distributions along the blade surface are investigated at mid-span to clarify the cause of the hysteresis. The result has shown that the hysteresis characteristics become more pronounced as blade thickness becomes larger. The occurrence of these characteristics depends on the varying behavior of wakes between an accelerating flow and a develerating flow.

• Journal of Korean Society for Quality Management
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• v.42 no.3
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• pp.325-338
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• 2014

Purpose: The purpose of this study was to explain de-painting phenomenon of KUH-1 tail blade and to propose useful solution of it by test. The proposed solution was evaluated by real flight, and then it applied to mass product to improve the paint qual ity of KUH-1 tail blade. Methods: This study investigated an adhesive ability of primer following surface sanding condition. The cross cut and scratch test were conducted to evaluate the adhesive strength. And the water flow test was designed to simulate a real flight condition under rain. Through water flow test, an optimal condition of tail blade to prevent a de-painting phenomenon was deduced. Finally, the improvement method was evaluated by real flight under rain. Results: The results of this study are as follows; The sequential polishing was most excellent method in primer painting quality. The results of test including cross cut, scratch and water flow showed that MIL-DTL-53039 paint with epoxy primer has excellent adhesive ability. To proof the effect of improvement, a real flight during a rain condition was conducted. Finally, the comparison between original and improved configuration was conducted. Conclusion: The painting quality of KUH-1 tail blade was improved through deriving an optimal painting condition. In detail, a condition of optimal sanding and a sort of primer and paint was showed. Finally, the reliability of tail blade was guaranteed through improving the quality of painting.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2009.05a
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• pp.435-436
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• 2009

In the effort on cost reduction in marine equipment company, the medium sized impeller blade ($500mm{\times}200mm{\times}20mm$) of an axial flow pan was manufactured by the high pressure die casting, with which was replaced the gravity die casting. High pressure die casting is a practical alternative because of some advantages such as excellent accuracy and smooth cast surface as well as cost reduction if a certain amount of porosity in the parts can be minimized. In order to reduce the porosity in the center of the neck which is thickest region of the impeller blade, the several gate designs were proposed in this work. The flow simulations for each gate design were performed and then the optimal design was determined by considering the air pressure distribution in neck section. Finally, the size of porosity in the neck of the die cast impeller blade for optimal design was less than 1mm, which satisfied the requirement.

• The KSFM Journal of Fluid Machinery
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• v.16 no.5
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• pp.5-10
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• 2013

The regenerative pump is a kind of turbomachine which is capable of developing high pressure rise at relatively lower flow rates compared to the centrifugal and axial pumps. Although the efficiency of regenerative pumps is much lower than other turbomachines, still they have been widely used in many industrial applications for working at low specific speeds. There are some theoretical models to analysis the pump performance, however, the effect of the blade angle on the pump performance has not been covered in any model to date. In the present study, experimental study on the regenerative pump performance according to the impeller blade angle and its shape has been carried out. The straight radial blades with forward, backward and chevron blades which have inclined angles of $15^{\circ}$, $30^{\circ}$ and $45^{\circ}$ were tested. The pump performance characteristics as the pressure head, efficiency were obtained depending on the flow rate for every impeller, and their results, expressed in appropriate non-dimensional coefficients, were compared and analysed in detail. From the experimental results, it was found that the pressure head and the efficiency depend strongly on the blade angles as well as the blade type. These experimental data has made it possible to better understand the effects of the blade angle on the pump performance, and widen the applicability of the current performance analysis and design models with including the effect of blade angles.

• Proceedings of the KSME Conference
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• 2001.06d
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• pp.961-966
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• 2001

The Wells turbine is one of the simplest and most promising self-rectifying air turbines which are useful for the systems of alternative energy development in near future, and it is economically desirable from the point of view of the practical use, as well. To investigate the effect of blade sweep on the performance of the Wells turbine, computations of a fully 3-D Navier-Stokes are carried out under steady flow conditions of NACA0020 blade. It is known that the performance of the Wells turbine is considerably influenced by the blade sweep. An optimum blade sweep ratio(f=0.35) for the NACA0020 is found to be the most promising for the practical use, and this value is in good agreement with the previous experiments. It is also found that the overall turbine performance for the NACA0020 is better than that for the CA9.

• Journal of KSNVE
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• v.7 no.5
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• pp.819-826
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• 1997

The finite element analyses of a composite hingeless rotor blade in forward flight have been performed to investigate the influence of blade design parameters on the blade stability. The blade structure is represented by a single cell composite box-beam and its nonclassical effects such as transverse shear and torsion-related warping are considered. The nonlinear periodic differential equations of motion are obtained by moderate deflection beam theory and finite element method based on Hamilton principle. Aerodynamic forces are calculated using the quasi-steady strip theiry with compressibility and reverse flow effects. The coupling effects between the rotor blade and the fuselage are included in a free flight propulsive trim analysis. Damping values are calculated by using the Floquet transition matrix theory from the linearized equations perturbed at equilibrium position of the blade. The aeroelastic results were compared with an alternative analytic approch, and they showed good correlation with each other. Some parametric investigations for the helicopter design variables, such as pretwist and precone angles are carried out to know the aeroelastic behavior of the rotor.