• The KSFM Journal of Fluid Machinery
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• v.14 no.3
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• pp.59-64
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• 2011

Wind turbine frame will be required to be longer, lighter, more reliable and more consistent. Therefore it is necessary to lose weight of the wind turbine hub. Light-weight Design of a wind turbine is required to be at least 20 years. Therefore, this paper investigates the development for wind turbine rotor hub using design of topology optimization. The model is a pitch regulated wind turbine with three rotor blades where the main frame is made of nodular iron. For optimization, calculating stresses based on displacements and based on these data to carry out a verification of static and fatigue strength carried out. For this verification, two kind of analysis is used. One is static analysis and the other is fatigue analysis. Then the rotor hub of wind turbine frame is optimized using topology method.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.13 no.5
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• pp.390-395
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• 2000

The ultrasonic motor have recently begun to be used for certain unique practical utilizations in the fields of industrial medical consumer and automotive applications. Ultrasonic motor stimulated to ultrasonic oscillations by piezoelectrics to drive a rotor via friction contact. The metal and ceramic composite component was used as the stator element to generate ultrasonic vibrations. The ultrasonic motor used here was the windmill type ultrasonic motor operated by single-phase AC source. The windmill type ultrasonic motors has only three components; a stator element of two windmill shape slotted metal endcaps a rotor and a bearing. In this paper a prototype motor with 11.35 mm diameter was fabricated then relationship between the pressing force applied to a rotor and the rotation characteristic of windmill type ultrasonic motor are investigated when stator’s slots was changed from 4, 6, 8 and thickness changed from 0.15, 0.20 mm, respectively. Optimum pressing force applied to a rotor in the six stators was 1.2 mN.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2012.05a
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• pp.117-122
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• 2012

A blisk with rotor shroud is usually adopted in LRE turbine to maximize its performance. However it experiences severe thermal load and resulting damage during engine stating and stop. Shroud splitting is devised to relieve thermal stress on the turbine rotor. Structural analysis confirmed the reduction of plastic strain at the blade hub and tip. However, split gap at the rotor shroud entails additional tip leakage and results performance degradation. In order to assess the effect of shroud split on the turbine performance, tests have been performed for various settings of shroud split. For the maximum number of shroud splitting, measured efficiency reduction ratio was 2.65% to the value of original shape rotor.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.7
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• pp.347-352
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• 2019

This study focused on improving the cast quality of small-sized induction motor rotors during the die casting process. A new rotor core cast model was proposed based on previous research results and parametric studies. Numerical analyses using 3-dimensional half models were performed to evaluate the filling patterns of aluminum molten metals into a mold and on-site experiment performed to verify the newly proposed cast model. The following were obtained from numerical filling analyses and experimental results. First, molten metals started to fill the lower end ring, then moved on to fill the core slot and upper end ring and finally stopped to fill at the rotor core slot. Second, significant circulation of molten metals was not observed on the lower end ring, resulting in fewer defects at the section of the lower end ring from the experimental results. Third, the new shape of a rotor core cast was effective in producing rotors with sound cast quality, and reducing the end ring cast defect area by approximately 70 %.

• Journal of Power Electronics
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• v.13 no.4
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• pp.546-551
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• 2013

This paper deals with the optimum design of the stator and rotor shape of the interior permanent magnet synchronous motors (IPMSM) that are used in applications for automobiles. IPMSMs have the following advantages: high power, high torque, high efficiency, etc. However, cogging torque which causes noise and vibrations is generated at the same time. The optimum design of shape of a IPMSM was carried out with the aim of reducing cogging torque. Six variables which affect to the performance of a IPMSM are chosen. The main effect variables were determined and applied to the response surface methodology (RSM). When compared to the initial model using the finite elements method (FEM), the optimum model highly reduces the cogging torque and improves the total harmonics distortion (THD) of the back-electro motive force (EMF). A prototype of the designed model was manufactured and experimented on to verify the feasibility of the IPMSM.

• Journal of Mechanical Science and Technology
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• v.16 no.8
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• pp.1154-1164
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• 2002

Losses on the turbine consist of the mechanical loss, tip clearance loss, secondary flow loss and blade profile loss etc.,. More than 60 % of total losses on the turbine is generated by the two latter loss mechanisms. These losses are directly related with the reduction of turbine efficiency. In order to provide a new design methodology for reducing losses and increasing turbine efficiency, a two-dimensional axial-type turbine blade shape is modified by the optimization process with two-dimensional compressible flow analysis codes, which are validated by the experimental results on the VKI turbine blade. A turbine blade profile is selected at the mean radius of turbine rotor using on a heavy duty gas turbine, and optimized at the operating condition. Shape parameters, which are employed to change the blade shape, are applied as design variables in the optimization process. Aerodynamic, mechanical and geometric constraints are imposed to ensure that the optimized profile meets all engineering restrict conditions. The objective function is the pitchwise area averaged total pressure at the 30% axial chord downstream from the trailing edge. 13 design variables are chosen for blade shape modification. A 10.8 % reduction of total pressure loss on the turbine rotor is achieved by this process, which is same as a more than 1% total-to-total efficiency increase. The computed results are compared with those using 11 design variables, and show that optimized results depend heavily on the accuracy of blade design.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2005.11a
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• pp.34-39
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• 2005

In this study, 3-D nozzle shape and the shape of nozzle at exit plane were adopted as design parameter of 3-D supersonic nozzle and numerical analyses for these parameters have been performed to investigate the flow and performance characteristics for design parameters of the turbine. Firstly, comparing results for nozzle shape, rectangular nozzle had less total pressure loss occurred in axial gap and more power by 1.5% than circular nozzle did. Next, comparing the results for the shape of nozzle at exit plane, it is found that the performance of partial admission turbine was largely depended upon the gap between nozzle wall at exit plane and the hub / tip of rotor blade and the length between nozzles.

• Journal of Electrical Engineering and Technology
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• v.1 no.3
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• pp.320-326
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• 2006

A single-phase line-start synchronous reluctance motor (LSSynRM) has merits of low cost, high efficiency and reliability. LSSynRM has an unbalanced magnetic circuit caused by flux barriers and various shapes of conductor bars when starting. Thus the motor may generate unstable starting torque in accordance with the initial starting position of the rotor. This paper presents the rotor design to improve starting performance of the LSSynRM. Design variables are the number and the shape of the conductor bars. This design result is compared with the initial prototype and single-phase induction motor.

• Proceedings of the KIEE Conference
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• 2008.04c
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• pp.38-40
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• 2008

This paper presents the torque ripple and vibration characteristic of interior type permanent magnet (IPM) motor according to rotor design. In the design methods, the optimal notchs are put on the rotor pole face, which have an effect on variation of permanent magnet (PM) shape or residual flux density of PM. Through the space harmonics field analysis, the positions of notch are found and the optimal shapes of notch are decided by using Finite Element Method (FEM). The validity of the proposed method is confirmed with experiments. Therefore, the vibration, starting current and efficiency of IPM is measured by experiment.

• Proceedings of the KIEE Conference
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• 1994.07a
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• pp.363-365
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• 1994

In switched reluctance motors(SRM), shaft position sensing is essential in order to synchronize the excitation pulse of a pertinent phase to the rotor position. This paper describes the operation of SRM drive using a simple position sensor of low cost. The position sensor is composed of a slotted disk similar to the rotor core shape of a prototype 6/4 SRM and three opto-interrupters disposed at an angle of 30 degrees. The phase current waveforms measured at several rotor speeds in experiment arc compared with those obtained through the computer simulation.