• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회B
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• pp.3247-3252
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• 2007

Endwall losses contribute significantly to the overall losses in modern turbomachinery, especially when aerodynamic airfoil load and pressure ratio are increased. Hence, reducing the extend and intensity of the secondary flow structures helps to enhance overall efficiency. From the large range of viable approaches, a promising combination positioning and height of endwall contouring was chosen. The objective of this study is to document the three-dimensional flow in a turbine cascade in terms of streamwise vorticity, total pressure loss distribution and static pressure distribution on the endwall and blade surface and to propose an appropriate positioning and height of the endwall contouring which show best secondary, overall loss reduction among the simulated endwall. The flow through the gas turbine were numerically analyzed using three dimensional Navier-Stroke equations with a commercial CFD code ANSYS CFX-10. The result shows that the overall loss is reduced near the flat endwall rather than contoured endwall, and the case of contoured endwall installed at 30% from leading edge with height of 25% for span showed best performance.

• 한국전산유체공학회지
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• 제20권2호
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• pp.1-6
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• 2015

In this study, a numerical prediction on propulsive performance of a ducted propeller in open water condition was carried out by solving Reynolds averaged Navier-Stokes(RANS) equation using computational fluid dynamics(CFD). A configuration of propeller Ka-470 inside duct 19A was considered. Hexahedral grid system was generated by dividing whole computational domain into three separate regions; propeller, duct and outer flow region. A commercial CFD software, ANSYS-CFX was used for numerical simulations. Results were compared with experimental data and showed considerable improvement in accuracy, in comparison to those from surface panel method which is based on potential flow assumption. The results also exhibited the importance of grid system within the gap between the inner surface of duct and blade tip for accurate prediction of propulsive performance of ducted propeller.

• 한국전산유체공학회지
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• 제20권2호
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• pp.52-60
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• 2015

The objective of this research lies in the effect of installation parameters influencing on the wind proof performance of the coastal forest for damage prevention. The dissipation ratio of incident wind power is developed as an assessment index to make a lumped parameter study possible. From the real field data of East, West, and South Sea bounded on the Korean peninsula, single and double storied forests were modeled in three-dimensional shape with computer aided design, and so was done the artificial structures such as wind break, sand accumulating fence, and sand dune, etc With a commercial code ANSYS-CFX, the computational result from the comparison of dissipation ratio between single and double storied forest shows the effect of composition, and also the installation effect is investigated for artificial structures with optimal dimension of distance.

• 설비공학논문집
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• 제27권4호
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• pp.220-227
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• 2015

Complex thermal hydraulic characteristics exist inside the reactor because the reactor internals consist of fuel assembly, internal structures and so on. In this study, to examine the effect of Reynolds-Averaged Navier-Stokes (RANS)-based two-equation turbulence models in the analysis of flow distribution inside a 1/5 scaled-down APR+, simulation was performed using the commercial computational fluid dynamics software, ANSYS CFX R.13 and the predicted results were compared with the measured data. It was concluded that reactor internal flow pattern was locally different depending on the turbulence models. In addition, the prediction accuracy of k-${\varepsilon}$ model was superior to that of other two-equation turbulence models and this model predicted the relatively uniform distribution of core inlet flow rate.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2010년도 춘계학술대회 초록집
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• pp.236.1-236.1
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• 2010

Due to global warming, the need to secure an alternative resource has become more important nationally. Due to the high tidal range of up to 9.7m on the west coast of Korea, numerous tidal current projects are being planned and constructed. The rotor, which initially converts the energy, is a very important component because it affects the efficiency of the entire system, and its performance is determined by various design variables. In this paper, a design guideline of current generating HAT rotor and acceptable field rotor in offshore environment is proposed. To design HAT rotor model, wind mill rotor design principles and turbine theories were applied based on a field HAT rotor experimental data. To verify the compatibility of the rotor design method and to analyze the properties of design factors, 3D CFD model was designed and analysed by ANSYS CFX. The analysis results and findings are summarized in the paper.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2010년도 춘계학술대회 초록집
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• pp.237.2-237.2
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• 2010

Although oscillating water column type wave energy devices are nearing the stage of commercial exploitation, there is still much to be learnt about many facets of their hydrodynamic performance. The techniques of Computational Fluid Dynamics (CFD) are applied to simulate a wave energy conversion device in free surface such as waves. This research uses the commercially available ANSYS CFX computational fluid dynamics flow solver to model a complete oscillating water column system with savonius turbine incorporated at the rear bottom of the OWC chamber in a three dimensional numerical wave tank. The purpose of the present study is to investigate the effect of an average wave condition on the performance and internal flow of a newly developed direct drive turbine (DDT) model for wave energy conversion numerically. The effects of blade angle and front lip shape on the hydrodynamic efficiency are investigated. The results indicated that the developed models are suitable to analyze the water flow characteristics both in the chamber and in the turbine. For the turbine, the numerical results of torque were compared for the all cases. The results of the testing have also illustrated that simple changes to the front wall aperture shape can provide marked improvements in the efficiency of energy capture for OWC type devices.

• 한국소음진동공학회논문집
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• 제23권4호
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• pp.308-314
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• 2013

The vibration and stress analysis program of comprehensive vibration assessment program(CVAP) is to theoretically verify the structural integrity of reactor vessel internals(RVI) and to provide the basis for selecting the locations monitored in measurement and inspection programs. This paper covers the applicability of the vibration and stress analysis method of APR1400 RVI CVAP. The analysis method was developed to use 3-dimensional detail hydraulic and structural models with ANSYS and CFX. To assess the method, the hydraulic loads and structural reponses of OPR1000 were predicted and compared with the measured data in the OPR1000 RVI CVAP. The results predicted with this method were close to the measured values considerably. Therefore, the analysis method was developed properly.

• 동력기계공학회지
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• 제21권3호
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• pp.51-59
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• 2017

In the early design stage of underwater vehicles, it is important to estimate the vehicle's underwater motion performance. The key design elements for the motion are propellers, battery power, and underwater resistance of the vehicle. Small thrusters with motor and propeller are usually used for the UUV(unmanned underwater vehicles). In this study, a multiphysics thruster model combining electro-mechanical and hydrodynamics characteristics was proposed to estimate the thruster performance. To show the applicability of the mathematical model, an sample thruster was used for the derive the unknown parameters of thruster. Hydrodynamic parameters were calculated for a 3D geometry model of the propeller by ANSYS/CFX program. Finally, Matlab/simulink program was used for the numerical simulation to predict the thruster performance from the given voltage/current input to the motor. Also, proved validity of simulation model by experiment test. Test were done by 2 mode(middle/high speed, reverse). The thruster performance curves obtained from this simulation were confirmed to be similar with experiment results.

• Journal of Advanced Research in Ocean Engineering
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• 제1권3호
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• pp.176-185
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• 2015

Recently, focus has been placed on ocean energy resources because environmental concerns regarding the exploitation of hydrocarbons are increasing. Tidal current power, one of the ocean energy resources, has great potential worldwide due to its high energy density. The flow velocity is the most crucial factor for the power estimation of TCP(Tidal Current Power) system since the kinetic energy of the flow is proportional to the cube of the flow speed. So sufficient inflow speed to generate electricity from the tidal current power is necessary. A duct system can accelerate the flow velocity, which could expand the applicable area of TCP systems to relatively lower velocity sites. The shapes of the inlet and outlet could affect the flow rate inside the duct. To investigate the performance of the duct, various ducts were preliminary designed considering the entire system that is single-point moored TCP system and a series of simulations were carried out using ANSYS-CFX v13.0 CFD software. This study introduces a ducted turbine system that can be moored to a seabed. A performance estimation and comparison of results with conventional tidal converters were summarized in this paper.

• 전기학회논문지P
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• 제66권4호
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• pp.158-162
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• 2017

This paper did basic study on the vertical-axis wind turbine. Namely, This paper was try to find the optimum conditions by using the ANSYS CFX simulation program through the changes of the main-blade angle and sub-blade angle. Main-blade Shape #4 angle $45^{\circ}$ compared to others Shape angle $0^{\circ}$ was increased by 157.2[%] to 263.2[%] in the power output and was increased by 110[%] to 250[%] in the power coefficient. Also, when the Shape #5 Fin length of main-blade doubles, because the power output was 70.8[%] compared to Shape #1 and 27.5[%] compared to Shape #4, and the power coefficient was 60[%] compared to Shape #1 and 28.6[%] compared to Shape #4, the power output and the power efficiency were rather reduced. The output current of Shape #4 was increased 109.9[%] compared to Shape #1 and increased 250[%] compared to Shape #5, and The output voltage of Shape #4 was increased 22.5[%] compared to Shape #1 and increased 3.7[%] compared to Shape #4.