• Journal of Astronomy and Space Sciences
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• 제2권2호
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• pp.153-174
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• 1985

The one of critical factor in gas turbine engine performance is high turbine inlet gas temperature. Therefore, the turbine rotor has so many problems which must be considered such as the turbine blade cooling, thermal stress of turbine disk due to severe temperature gradient, turbine rotor tip clearance, under the high operating temperature. The purpose of this study is to provider the temperature distribution and heat flux in turbine disk which is required to considered premensioned problem by the Finite Difference Method and the Finite Element Methods on the steady state condition. In this study, the optimum aspect ratio of turbine disk was analysed for various heat conductivity of turbine disk material by Finite Difference Method, and the effect of laminating method with high conductivity materials to disk thickness direction by Finite Element Methods in order to cool the disk. The laminating method with high conductivity material on the side of the disk is effective.

• 대한기계학회논문집A
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• 제20권8호
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• pp.2524-2539
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• 1996

A design process and an axisymmetric boundary integral equation method for precise structural analysis of the aircraft gas turbine rotor disk were developed. This axisymmetric boundary integral equation method for stress and steady-state thermal analysis was improved in solution accuracy by appling an implicit technique for Cauchy principal value evaluation, a subelement technique for weak singular integral evaluation and a double exponentical integral technoque for internal point solution near boundary surfaces. Stresses, temperatures, low cycle fatigue lifes and critical speeds for the turbine rotor disk of the thrust 1421 N class turbojet engine were analysed in a pratical calculation model problem.

• 비파괴검사학회지
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• 제29권5호
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• pp.493-500
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• 2009

본 연구에서는 터빈 로터 디스크 키웨이에 발생하는 균열의 상세 정보를 추출하기 위하여 초음파 신호처리 알고리즘을 개발하였다. 초음파 검사 시스템에 의한 터빈 로터 디스크 키웨이 시험편의 초음파 신호로부터 B-주사 이미지를 구성하였다. 구성된 B-주사 이미지를 2차원 신호처리를 위한 입력영상으로 이용하여, 전처리, 균열후보영역 검출, 균열영역 판별 및 균열정보 추출의 4단계로 알고리즘을 구성하였다. 개발된 초음파 신호처리 알고리즘을 이용한 실험을 통하여, 개발된 알고리즘이 키웨이 부위에 발생하는 균열의 특징정보 추출에 의한 균열의 정량적인 평가에 효과적임을 확인하였다.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2004년도 제22회 춘계학술대회논문집
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• pp.831-838
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• 2004

A fluid-solid conjugate solver has been newly developed and applied to an actual engine disk system. Most of the currently available conjugate solvers lack the special thermal modeling for turbomachinery disk system applications. In the present new code, these special models are implemented to expand the applicability of the conjugate method and to reduce the required computational resources. Most of the conjugate analysis work so far are limited to the axisymmetric framework. However, the actual disk system includes several non-axisymmetric components which inevitably affect the local heat transfer phenomena. Also the previous work devoted to this area usually concentrate their efforts on the steady-state thermal field, although the one in the transient condition is more critical to the engine components. This paper presents full 3D conjugate analysis of a single stage high pressure turbine rotor-stator disk system to assess the three-dimensional effects (Fig. 1). The analysis is carried out not only in the steady-state but also in the engine accelerating transient condition. The predicted temperatures shows good agreement with measured data.

• 한국군사과학기술학회지
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• 제1권1호
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• pp.128-144
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• 1998

일반적인 선형 탄성해석 경계 요소법이 초 고속 회전과 정상 열전도에 의한 열 탄성 효과가 고려된 문제에 적용되었다. 축대칭 경계 요소법 구성이 요약되었고, 등가 경계 적분 방정식의 물체력 핵 함수의 체적 적분 전환방법에 일반화된 내적과 벡터 연산법 개념이 도입되었다. 고차 경계 요소 적용을 위한 이산화 수치 해석법이 요약되었고, 소형 젯트 엔진(ADD 500)의 터어빈 로우터 디스크의 해석 결과가 유한 요소해와 비교되었다.

• International Journal of Fluid Machinery and Systems
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• 제3권1호
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• pp.67-79
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• 2010

Severe flexural vibration of the rotor shaft of a Francis turbine runner was experienced in the past. It was shown that the vibration was caused by the fluid forces and moments on the backshroud of the runner associated with the leakage flow through the back chamber. The aim of the present paper is to study the self-excited rotor vibration caused by the fluid force moments on the backshroud of a Francis turbine runner. The rotor vibration includes two fundamental motions, one is a whirling motion which only has a linear displacement and the other is a precession motion which only has an angular displacement. Accordingly, two types of fluid force moment are exerted on the rotor, the moment due to whirl and the moment due to precession. The main focus of the present paper is to clarify the contribution of each moment to the self-excited vibration of an overhung rotor. The runner was modeled by a disk and the whirl and the precession moments on the backshroud of the runner caused by the leakage flow were evaluated from the results of model tests conducted before. A lumped parameter model of a cantilevered rotor was used for the vibration analysis. By examining the frequency, the damping rate, the amplitude ratio of lateral and angular displacements for the cases with longer and shorter overhung rotor, it was found that the precession moment is more important for smaller overhung rotors and the whirl moment is more important for larger overhung rotors, although both types of moment due to the leakage flow can cause self-excited vibration of an overhung rotor.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2009년도 춘계학술대회 논문집
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• pp.22-25
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• 2009

본 연구에서는 커빅커플링의 설계, 구조해석, 고온 비틀림시험 및 실형상 축-디스크를 제작/조립성 검토를 통해 터보펌프 터빈에의 적용 가능성을 타진하였다. 커플링의 치형은 Gleason 치형을 기본형상으로 하여 설계운용조건의 1.5배의 토크값을 기준으로 설계를 진행하였다. 구조해석 및 고온비틀림 시험을 통해 하중조건하의 안정성을 확인하였으며 특히 비틀림시험 후 커플링의 변형은 미미함을 확인하였다. 커빅커플링을 적용한 실형상 디스크 제작 및 조립시험을 통해 설계요구조건을 하회하는 디스크의 외주 및 축방향 흔들림 그리고 조립재현성을 확인하였다.

• 풍력에너지저널
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• 제4권1호
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• pp.68-74
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• 2013

Offshore wind farm is being increased since there are much trouble to develop onshore wind farm. But in the offshore, wind turbine wake does not dissipate less than onshore wind turbine because of low turbulence level. Thus this remained wake interacted to other wind turbine. This interaction reduces energy production in wind farm and have a bad influence on fatigue load of wind turbine. In this research, CFD model was constructed to analyze wake effect in offshore wind farm. A method that wind turbine rotor region was modelled in porous media was devised to reduce computation load and validated by comparison with Horns Rev measurement. Then wake interaction between two wind turbine was analyzed by devised porous model.

• International Journal of Fluid Machinery and Systems
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• 제3권3호
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• pp.235-244
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• 2010

Recent studies on the moment whirl due to leakage flow in the back shroud clearance of hydro-turbine runners or centrifugal pump impellers are summarized. First, destabilizing effect of leakage flow is discussed for lateral vibrations using simplified models. Then it is extended to the case of whirling motion of an overhung rotor and the criterion for the instability is obtained. The fluid moment caused by a leakage clearance flow between a rotating disk and a stationary casing was obtained by model tests under whirling and precession motion of the disk. It is shown that the whirl moment always destabilizes the whirl motion of the overhung rotor while the precession moment destabilizes the precession only when the precession speed is less than half the rotor speed. Then vibration analyses considering both whirl and precession are made by using the hydrodynamic moments determined by the model tests. For larger overhung rotors, the whirl moment is more important and cause whirl instability at all rotor speed. On the other hand, for smaller overhung rotors, the precession moment is more important and cancels the destabilizing effect of the whirl moment.

• 대한기계학회논문집A
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• 제20권6호
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• pp.1784-1797
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• 1996

The disk/blade assembly of a turbine engine is made in the shape of a dovetail type or a fir-tree type. Since disk fillet regions or contact surfaces undergo high stress comcentration, fatigue cracks frequentrly occur in the disk/blade assembly. Therefore, it is necessary to analyze the stress distributions in the fir-tree type disk/balde assembly and predict the region of fatigue failure. The stress distributions of the disk/blade assembly were investigated by using the photoelastic method and the finite element method. Two dimensional photoelastic techniques were used to investigate the stress distributions of contact surfaces and fillet regions. TH stress distributions were obtained by the shear-difference method and were compared to the finite element results. It was found that maximum tensile stresses were higher in the fillet region thatn in the contact surfaces of the fir-tree models. The finite element results showed good agreement with the experimental results.