• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회A
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• pp.832-837
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• 2008

A modeling method for the modal analysis of a multi-packet blade system having tapered cross section undergoing rotational motion is presented in this paper. Blades are idealized as tapered cantilever beams that are fixed to a rotating disc. The stiffness coupling effects between blades due to the flexibilities of the disc and the shroud are modeled with discrete springs. Hybrid deformation variables are employed to derive the equations of motion. To obtain more general information, the equations of motion are transformed into dimensionless forms in which dimensionless parameters are identified. The effects of the dimensionless parameters including tapered ratio and the number of packets as well as blades on the modal characteristics of the system are investigated with some numerical examples.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2003년도 추계학술대회논문집
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• pp.944-949
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• 2003

This paper addresses the control of free and dynamic response of composite rotating pretwisted blade modeled as non-uniform thin-walled beam fixed at the certain presetting and pretwisted angle and incorporating piezoelectric induced damping capabilities. A distributed piezoelectric actuator pair is used to suppress the vibrations caused by external disturbances. The blade model incorporates non-uniform features such as transverse shear, secondary warping and includes the centrifugal and Coriolis force field. A velocity feedback control law relating the piezoelectiriccally induced transversal bending moment at the beam tip with the appropriately selected kinematical response quantity is used and the beneficial effects upon the closed loop eigenvibration and dynamic characteristics of the blade are highlighted.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2006년도 춘계학술대회논문집
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• pp.1354-1359
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• 2006

A modeling method for the vibration analysis of rotating multi-blade systems considering the coupling stiffness effect is presented in this paper. Blades are assumed as cantilever beams and the coupling stiffness effect originates from disc or shroud between blades. As the angular speed, hub radius ratio, and the coupling stiffness vary, the natural frequencies of the system vary. Numerical results show that the coupling stiffness is very important to estimate the natural frequencies. Along with the natural frequencies, associated mode shapes, critical angular speed, and critical hub radius ratio are obtained through the analysis.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2000년도 추계학술발표대회 논문집
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• pp.187-190
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• 2000

Cyclocopter is air vehicle to vertically take-off and land like a helicopter. This is an efficient and quiet means of being able to direct thrust compared to a helicopter. The rotor consists of several blades rotating about a horizontal axis perpendicular to the direction of normal flight. The direction of blade span is parallel to rotating axis and both end roots are connected to the hub to resist centrifugal force and to transmit the power. The pitch of the individual blades to the tangent of the circle of the blade's path is varied cyclically to gain thrust. In the paper, the design and manufactures of cyclocopter rotor blades are presented. Stress at the roots of cyclocopter blades is great due to centrifugal and aerodynamic forces and aeroelastic instabilities appear. The blades consist of main spar, front spar, polyurethan foam, weight, and skin and spars and skin are made of glass/epoxy composite.

• 융복합기술연구소 논문집
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• 제6권1호
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• pp.37-41
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• 2016

The serpentine internal passage is located in turbine blade and it shows the variety heat transfer distribution. Especially, the Coriolis force, which is induced by blade rotation, makes different heat transfer distribution of the leading and trailing surfaces of serpentine internal passage. The different heat transfer is one of the reasons why the serpentine cooling passage shows low cooling performance in the rotating condition. So, this study tried to design the advanced the serpentine passage to consideration of the Coriolis force. The design concept of advanced serpentine cooling is maximizing cooling performance using the Coriolis force. So, the flow turns from leading surface to trailing surface in advanced serpentine passage to match the direction of Coriolis force and rotating force. We performed numerical analysis using CFX and compared the existing and advanced serpentine internal passage. This design change is induced the high heat transfer distribution of whole advanced serpentine internal passage surfaces.

• 대한기계학회논문집A
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• 제23권11호
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• pp.2067-2077
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• 1999

Recently, turbomachine blades are becoming larger and more flexible, it is necessary to calculate natural frequencies of a rotating blades for avoiding resonance. This problem is complicated by the fact that blades are tapered, twisted and curved. To keep with this demands, the designer must rely on more exact methods of calculation. In this paper, natural frequencies of a single straight or curved blade with variable R.P.M. are calculated by a stiffness matrix method. Results of investigation on the correspondence between the calculated and other values of the literature are described. The calculated values are agree with the other values but with a small error. Furthermore, the influence of Coriolis force on the natural frequency for rotating, curved turbo blades is described.

• 한국자동차공학회논문집
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• 제5권5호
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• pp.197-212
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• 1997

The performance of a torque converter can be expressed by the performance parameters such as flow radius and flow angle, on the mean flow path. The geometric analysis of the torque converter is required to determine these parameters for the modeling of the torque converter. In general, the blade shape is depicted by three dimensional data at the mid-surface of blade or those of the pressure and suction side. To generate three dimensional model of the blade using the data mentioned above, a consistent data format and a shape generation algorithm are required. This paper presents a useful consistent data format of the blades and an algorithm for the geometrical shape generation. By the geometric analysis program to which the shape generation algorithm is embedded, the variation of blade angles in rotating element analyzed. Then finally, the analyzed results of geometric profile of a blade are compared with those of the blade design principle, so called forced vortex theorem.

• 한국소음진동공학회논문집
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• 제22권7호
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• pp.659-666
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• 2012

A nonlinear dynamic model for the shaft-disk-blade unit is developed in this study. In this regard, the rotating flexible blade, with a pre-twist angle, attached to a rigid disk driven by a shaft which is flexible in torsion is developed. The rotor-blade coupled model is derived using Lagrange equation in conjunction with the assumed mode method to discretize the blade deformation. The equations of motion are analyzed based on the small deformation theory for the blade and shaft torsional deformation to obtain the system natural frequencies for various system parameters.

• 산업공학
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• 제14권2호
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• pp.140-147
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• 2001

In the turbine-blade manufacturing industry, turbine-blades are machined and then are assembled to form a circular roll of blades. The roll of blades should be balanced as much as possible, since otherwise the efficiency of the turbine generator might be damaged. A locking blade is a blade whose location is fixed and a non-locking blade is a blade whose location can be freely changed. In this paper, we study methods for balancing the weights of the rotating blades for a turbine where some blades are locking blades. The turbine-blade balancing problem is formulated into a mixed-integer programming problem, which turns out to be NP-hard. A heuristic method based on the number partitioning algorithm is developed and the computational experiments show very promising results.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2005년도 추계학술대회논문집
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• pp.184-187
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• 2005

The blade is an important part of rotating turbomachinery. The blade dynamic strength is of considerable importance as far as the reliability of operation and the life of the engine ate concerned. In this paper, blades are attached to a disk and coupled by means of damping wire. We assumes that the interfaces between the blade and disk dovetails are joined together, which means surface-to-surface contacts without friction. The damping wire is implemented using a beam element and temperature effect in the blade is neglected. Centrifugal forces ale applied by using an angular velocity to all elements in the system. The FEM results showed vibration characteristics in the blade disk system for the cases of a free-standing blade and blades with damping wire, respectively.