• 제목/요약/키워드: Rotor-dynamics

검색결과 404건 처리시간 0.028초

터빈의 피치 간격이 가스터빈 엔진 성능에 미치는 영향 (The Effect of Turbine Blade Pitch on the Gas Turbine Engine Performance)

  • 김재민;김귀순;최정열;정용운;황인희
    • 한국추진공학회지
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    • 제12권6호
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    • pp.48-55
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    • 2008
  • CFD 기반으로 개발한 가스터빈 엔진 모사 프로그램을 바탕으로 간단한 엔진 모델의 성능을 모사해보았다. 2D NS 코드를 사용하여 압축기와 터빈을 모사하고, lumped method 화학 평형 코드를 사용하여 연소기를 모사하였다. 압축기, 터빈에서의 동익, 정익간의 상호 비정상 유동 현상은 mixing-plane 기법으로 정상 상태 해석을 수행하였다. 이러한 방법으로 정상 작동 상태에서의 터빈 익렬의 피치 간격이 엔진에 미치는 영향을 살펴보았다. 연구 결과, 터빈의 피치 간격이 좁아질수록 압축기는 더 높은 압력에서 작동하는 것을 확인하였다.

하드디스크 드라이브에 있어서 스핀들모터의 구조적 가진에 따른 시스템의 소음 특성에 관한 연구 (A Study On The Acoustic Noise Characteristics of Hard Disk Drive Due To The Structural Excitation Of Spindle Motor)

  • 손영;황태연;강성우;한윤식;구자춘
    • 한국소음진동공학회:학술대회논문집
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    • 한국소음진동공학회 2000년도 춘계학술대회논문집
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    • pp.1549-1554
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    • 2000
  • HDD structure is excited by the dynamic motion of disk-spindle motor components. Those excitations which are generated at stator and magnet rotor, at bearings and from disk dynamics, are transmitted through motor spindle and flange to HDD cover and base. The operational deflection shape measurement can show the structural excitation patterns at the most influent frequency on the acoustic noise level. One of those components is the axial excitation along spindle, and the other is the local orbital excitation at contact area of motor flange and base. To make a reduction of those structural transmission excitations, the structure of spindle motor is modified to the direction of reinforcement at transmission path without change of bearings, magnet and coil. Some excitation of spindle motor component carrying out essential function is unavoidable. So it is the efficient way of HDD noise improvement to control the structural transmission of excitation.

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해양 조류발전단지 간섭 연구 (Ocean Current Power Farm Interaction Study)

  • 조철희;임진영;채광수;박노식
    • 한국해양공학회지
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    • 제23권1호
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    • pp.109-113
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    • 2009
  • Several tidal current power plants are being planned and constructed in Korea utilizing the strong tidal currents along the west and south coasts. A tidal current reaches 9.7 m on the west coast; there are few potential regions for tidal current power generation. The construction of a dam to store water can prevent the circulation of water, causing a great environmental impact on the coast and estuary. The tidal barrage could produce a large amount of power, but it should be carefully considered. The purpose of developing renewable energies is to minimize the environmental impact and to maximize the utilization of clean energy. To produce a great quantity of power, tidal current farms require the placement of numerous units in the ocean. The power generation is very dependent on the size of the rotor and the incoming flow velocity. Also, the interactions between devices contribute greatly to the production of power. The efficiency of a power farm is estimated to determine the production rate. This paper introduces 3 D interaction problems between rotating rotors, considering the axial, transverse, and diagonal distances between horizontal axis tidal current devices.

미분변환법을 이용한 회전외팔보의 자유진동해석 (Free Vibration Analysis of a Rotating Cantilever Beam by Using Differential Transformation Method)

  • 신영재;지영철;윤종학;유영찬
    • 대한기계학회논문집A
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    • 제31권3호
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    • pp.331-337
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    • 2007
  • Rotating cantilever beams can be found in several practical engineering applications such as turbine blades and helicopter rotor blades. For reliable and economic design, it is necessary to estimate the dynamic characteristics of those structures accurately and efficiently since significant variation of dynamic characteristics resulted from rotational motion of the structures. Recently, Differential Transformation Method(DTM) was proposed by Zhou. This method has been applied to fluid dynamics and vibration problems, and has shown accuracy, efficiency and convenience in solving differential equations. The purpose of this study, the free vibration analysis of a rotating cantilever beam, is to seek for the reliable property of DTM and confidence in the results obtained by this method by comparing the results with that of finite element method applied to linear partial differential equations. In particular, this study is worked by supposing optional T-function values because the equations governing chordwise motion are based on two differential equations coupled with each other. This study also shows mode shapes of rotating cantilever beams for various rotating speeds.

Hydrofoil selection and design of a 50W class horizontal axis tidal current turbine model

  • Kim, Seung-Jun;Singh, Patrick Mark;Choi, Young-Do
    • Journal of Advanced Marine Engineering and Technology
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    • 제39권8호
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    • pp.856-862
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    • 2015
  • Tidal current energy is an important alternative energy resource among the various ocean energy resources available. The tidal currents in the South-Western sea of Korea can be utilized for the development of tidal current power generation. Tidal power generation can be beneficial for many fishing nurseries and nearby islands in the southwest region of Korea. Moreover, tidal power generation is necessary for promoting energy self-sufficient islands. As tidal currents are always available, power generation is predictable; thus, tidal power is a reliable renewable energy resource. The selection of an appropriate hydrofoil is important for designing a tidal current turbine. This study concentrates on the selection and numerical analysis of four different hydrofoils (MNU26, NACA63421, DU91_W2_250, and DU93_W_210LM). Blade element momentum theory is used for configuring the design of a 50 W class turbine rotor blade. The optimized blade geometry is used for computational fluid dynamics (CFD) analysis with hexahedral numerical grids. Among the four blades, NACA63421 blade showed the maximum power coefficient of 0.45 at a tip speed ratio of 6. CFD analysis is used to investigate the power coefficient, pressure coefficient, and streamline distribution of a 50 W class horizontal axis tidal current turbine for different hydrofoils.

1MW급 수평축 풍력터빈 로터 블레이드 설계 및 CFD에 의한 공력성능 평가 (Rotor Blade Design of a 1MW Class HAWT and Evaluation of Aerodynamic Performance Using CFD Method)

  • 모장오;이영호
    • 한국유체기계학회 논문집
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    • 제15권1호
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    • pp.21-26
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    • 2012
  • In this investigation, the aerodynamic performance evaluation of a 1MW class blade has been performed with the purpose of the verification of target output and its clear understanding of flow field using CFD commercial code, ANSYS FLUENT. Before making progress of CFD analysis the HERACLES V2.0 software based on blade element momentum theory was applied for confirmation of quick and approximate performance in the preliminary stage. The blade was designed to produce the target output of a 1MW class at a rated wind speed of 12m/s, which consists of five different airfoils such as FFA W-301, DU91-W250, DU93-W-210, NACA 63418 and NACA 63415 from hub to tip. The mechanical power by CFD is approximately 1.195MW, which is converted into the electrical power of 1.075MW if the system loss is considered to be 0.877.

복합재료 회전축의 진동 및 안정성 해석 (Vibration and Stability Analysis of Composite Spinning Shafts)

  • 서정석;안창기;박상윤;송오섭
    • 한국소음진동공학회논문집
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    • 제25권7호
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    • pp.510-517
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    • 2015
  • The free vibration and stability analysis of a spinning composite shaft modelled as a thin-walled closed beam is performed for several design parameters, such as ply angle, aspect ratio, and spin speed. The governing equations of spinning shafts based on the Timoshenko beam theory are derived via Hamilton's variational principle. Coriolis acceleration and anisotropy of constituent materials are incorporated in the derivation. The equations of motion are then transformed to the standard form of an eigenvalue problem for free vibration and stability analysis. Analytical results both for uniform circular cylindrical shaft and rectangular cross-section shaft are obtained by using extended Galerkin method, and the results are compared with those from FEM ANSYS analysis for a verification.

복합베어링으로 지지된 스핀들의 동적 해석 (Dynamic Analysis of Spindle Supported by Multiple Bearings of Different Types)

  • 통반칸;배규현;홍성욱
    • 한국정밀공학회지
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    • 제32권2호
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    • pp.117-125
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    • 2015
  • This paper presents a dynamic modeling method for the indeterminate spindle-bearing system supported by multiple bearings of different types. A spindle-bearing system supported by ball and cylindrical roller bearings is considered. The de Mul's bearing model is extended for calculating ball and cylindrical roller bearing stiffness matrices with inclusion of centrifugal force and gyroscopic moment. The dependence between spindle shaft reaction forces and bearing stiffness is effectively resolved using an iterative approach. The spindle rotor dynamics is established with the Timoshenko beam theory based finite elements. The spindle reaction forces, bearings stiffness and spindle natural frequencies are obtained with taking into account spindle radial load, ball bearing axial preload and rotational speed effects. The developed method is verified by comparing the simulation results with those from a commercial program.

회전하는 블레이드 주위의 유동가시화 및 전산유동해석 (Visualization and Computational Analysis for Flow around Rotating Blades)

  • 기현;최종욱;김성초
    • 한국가시화정보학회지
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    • 제8권1호
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    • pp.39-45
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    • 2010
  • The optimal design is needed for the blade geometry of the quad-rotor blades which is mainly used for Unmanned Aerial Vehicle. To do this, it is important to analyze the wakes under the blades. In the present study, the flow around the rotating blades was analyzed using PIV(Particle Image Velocimetry) and CFD(Computational Fluid Dynamics). The maximum axial velocity was measured at about 60% position toward the radial direction of the blade. The positions of vorticities in the test section obtained by PIV and CFD were turned out to be almost alike. The values in the difference of pressure coefficients at the upper and the lower blades were increased depending on the radial direction. Then, the values were decreased at the blade tip. The data of the flow analysis in the present study are expected to be served as the design of blades and ducts for the thrust improvement in the future.

스핀들 회전축계의 기전 연성 해석을 이용한 모바일 HDD의 자유 낙하 특성 및 감지에 관한 연구 (Characterization and Detection of a Free-falling State of a Mobile HDD Using the Electromechanical Analysis in a Rotating Spindle System)

  • 박상진;장건희;김철순;한재혁
    • 한국소음진동공학회논문집
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    • 제16권1호
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    • pp.12-18
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    • 2006
  • This research investigates the electromechanical characteristics of a spindle motor in a free-falling mobile hard disk drive before unexpected shock. Electromechanical simulation includes a time-stepping finite element analysis of the magnetic field in a speed controlled brushless DC motor and dynamic analysis of the stationary and rotating part linked by the fluid dynamic bearing under the free-falling condition. Analysis results show that the dynamic characteristics of the rotating spindle system during free-falling state have an effect on the relative motion between the stationary and rotating part of HDD. It results from the variation of reaction force in the bearing area due to the gravity force exerted on the rotating part of HDD, and the free-falling condition can be detected by observing the signal of the spindle motor and disk-head interface without using an accelerometer.