• Journal of Power System Engineering
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• v.13 no.6
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• pp.82-87
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• 2009

LDV measurements were conducted on the planes between impeller blades of torque converter. The flow fields are extremely complex because they contain unsteady viscous three-dimensional flows. Besides of their complexity, the difference in rotor speeds between the impeller and turbine compound the flow effects. The good spatial resolution of the LDV allows measurements of the instantaneous flow structures within the impeller passage, yielding valuable information about the production automotive torque converter in realistic operating conditions. It was found that the mass flow rates are strongly related with the internal flow characteristics of torque converter.

• International Journal of Fluid Machinery and Systems
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• v.3 no.2
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• pp.137-149
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• 2010

The purpose of the present research is to suppress cavitation instabilities by using a circumferential groove. The circumferential groove was designed based on CFD so that the tip leakage vortex is trapped by the groove and does not interact with the next blade. Experimental results show that the groove can suppress rotating cavitation, asymmetric cavitation and cavitation surge. However, weak instabilities with higher frequency could not be suppressed by the groove. From the analysis of pressure pattern similar to that for rotor-stator interaction, it was found that the higher frequency components are caused by the interaction of backflow vortices with the inducer blades.

• 유체기계공업학회:학술대회논문집
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• 2002.12a
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• pp.279-283
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• 2002

The effects of finite gap at the tip of turbomachinery blades have long been topics of both theoretical and experimental research because tip clearance degrades turbomachinery performance. This paper presents an analytical study of radial flow redistribution in a high speed compressor stage with axisymmetric tip clearance. The flow is assumed to be inviscid and compressible. The stage is modeled as an actuator disc and the analysis is carried out in the meridional plane. Upon going through the stage, the radially uniform upstream flow splits into the tip clearance and passage flows. The tip clearance flow is modeled as a jet driven by blade loading, or pressure difference between the pressure and suction sides. The model takes into consideration the detached shocks which occur in the rotor passage at the design point. This shock model is used to calculate the density ratio across the stage. Thus, the model is capable of predicting the kinematic effects of tip clearance in the high speed compressor flow field.

• 한국신재생에너지학회:학술대회논문집
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• 2005.06a
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• pp.33-36
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• 2005

A critical issue in the field of the rotor aerodynamics is the treatment of the wake. The wake is of primary importance in determining overall aerodynamic behavior, especially, a wind turbine blade includes the unsteady air loads problem. In this study, the wake generated by blades are depicted by a free wake model to analyse unsteady loading on blade and a new free wake model named Finite Vortex Element(FVE hereafter) is devised in order to include a wake-tower interact ion. In this new free wake model, blade-wake-tower interaction is described by cutting a vortex filament when the filament collides with a tower. This FVE model is compared with a conventional free wake model and verified by a comparison with NREL and SNU wind tunnel model. A comparison with NREL and SNU data shows validity and effectiveness of devised FVE free wake model and an efficient.

• 한국신재생에너지학회:학술대회논문집
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• 2008.05a
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• pp.286-289
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• 2008

Wind turbine industry is booming and spending a lot on research for improving the performance of its present machines and increasing their capacity. Wind turbine requires service life of about 20 years and each components of wind turbine requires high durability, because installation and maintenance costs are more expensive than generated electricity by wind-turbine. So the design of wind turbine must be verified in various condition before production step. For this work, high reliability model for analysis is required. Drivetrain model is modeled by multibody dynamic modeling method. The model constituted with rotor blades, hub, main shaft, gear box, high speed shaft and generator. Natural frequency and torsional stiffness of drivetrain are calculated and analyzed.

• 한국전산유체공학회:학술대회논문집
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• 2004.03a
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• pp.42-48
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• 2004

Numerical simulation of viscous compressible flow in turbomachinery cascade involves many problems due to the complex geometry of blade but also flow phenomena. In the present study, numerical investigations have been performed to examine the three-dimensional flow characteristics inside the transonic linear turbine cascades using a commercial code, FLUENT. Multi-block H-type grids are applied to the high-turning turbine rotor blades and comparisons with the experimental data and the numerical results have been done. In addition, the effects of turbulence models on the prediction of the endwall flows are analyzed in the sense of the flow compressibility.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.40 no.8
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• pp.519-525
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• 2016

In a pump, from the performance point of view, it is very important to minimize the shock loss at the inlet of the rotor blades. In this study, the effects of shape and install angle of the inlet guide on the performance of an axial-flow pump are numerically simulated using commercial CFD code, Ansys CFX. Finally, to obtain the optimized shape of the vanes and the install angle of the vanes in the inlet guide under given operating conditions, optimization analysis is conducted using Analysis design exploration based on response surface optimization.

• Journal of Mechanical Science and Technology
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• v.18 no.6
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• pp.895-903
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• 2004

In this paper are presented the blade vibration characteristics at the starting conditions of the low pressure multistage axial compressor of heavy-duty 100 MW gas turbine. Vibration data have been collected through strain gauges during aerodynamic tests of the model compressor. The influences of operating modes at the starting conditions are investigated upon the compressor blade vibrations. The exciting mechanisms and features of blade vibrations are investigated at the surge, rotating stall, and buffeting flutter. The influences of operating modes upon blade dynamic stresses are investigated for the first and second stages. It is shown that a high dynamic stress peak of 120 MPa can occur in the first stage blades due to resonances with stall cell excitations or with inlet strut wake excitations at the stalled conditions.

• New & Renewable Energy
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• v.1 no.1 s.1
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• pp.54-63
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• 2005

A critical issue in the field of the rotor aerodynamics is the treatment of the wake. The wake is of primary importance in determining overall aerodynamic behavior, especially, a wind turbine blade includes the unsteady airloads problem. In this study, the wake generated by blades are depicted by a free wake model to analyse unsteady loading on blade and a new free wake model named Finite Vortex Element(FVE hereafter) is devised in order to include a wake-tower interaction. In this new free wake model, blade-wake-tower interaction is described by cutting a vortex filament when the filament collides with a tower. This FVE model is compared with a conventional free wake model and verified by a comparison with NRELand SNU wind tunnel model. A comparison with NREL and SNU data shows validity and effectiveness of devised FVE free wake model and an efficient.

• International Journal of Naval Architecture and Ocean Engineering
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• v.5 no.4
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• pp.625-634
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• 2013

Energy is a direct restriction to the working life of an underwater mooring platform (UMP). In this paper, a vertical axis water turbine (VAWT) is designed to supply energy for UMPs. The VAWT has several controlled blades, which can be opened or closed by inside plunger pumps. Two-dimensional transient numerical studies are presented to determine the operating performance and power output of the turbine under low ocean current velocity. A standard k-${\varepsilon}$ turbulence model is used to perform the transient simulations. The influence of structural parameters, including foil section profile, foil chord length and rotor diameter, on the turbine performance are investigated over a range of tip-speed-ratios (TSRs). It was found that turbine with three unit length NACA0015 foils generated a maximum averaged coefficient of power, 0.1, at TSR = 2.