• Journal of Mechanical Science and Technology
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• 제17권7호
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• pp.966-977
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• 2003

This paper investigates how intentional mistuning of bladed disks reduces their sensitivity to unintentional random mistuning. The class of intentionally mistuned disks considered here is limited, for cost reasons, to arrangements of two types of blades (A and B, say). A two-step procedure is then described to optimize the arrangement of these blades around the disk to reduce the effects of unintentional random mistuning. First, a pure optimization effort is undertaken to obtain the pattern (s) of the A and B blades that yields small/the smallest value of the largest amplitude of response to a given excitation in the absence of unintentional random mistuning using Genetic Algorithm. Then, in the second step, a qualitative/quantitative estimate of the sensitivity for the optimized intentionally mistuned bladed disks with respect to unintentional random mistuning is performed by analyzing their amplification factor, probability density function and passband/stopband structures. Examples of application with simple bladed disk models demonstrate the significant benefits of using this class of intentionally mistuned disks.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2004년도 추계학술대회논문집
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• pp.538-541
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• 2004

In turbomachinery rotor, there are small differences in the structural and/or geometrical properties of individual blades, which are referred to as blade mistuning. Mistuning effects of the forced response of bladed disks can be extremely large as often reported in many studies. In this paper, the pattern optimization of intentional mistuning for bladed disks considering with damping and coupling effect is the focus of the present investigation. More specifically, the class of intentionally mistuned disks considered here is limited, for cost reasons, to arrangements of two types of blades (A and B, say) and Genetic Algorithm is used to optimize the arrangement of these blades around the disk to reduce the forced response of blade with different damping and coupling stiffness.

• 한국항공우주학회지
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• 제31권8호
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• pp.77-84
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• 2003

액체로켓용 터보펌프 터빈 블레이드-디스크의 구조 및 진동 해석이 설계점에서의 구조 강도 및 동특성을 고찰하기 위하여 수행되었다. 터보펌프의 높은 회전 속도로 인하여 구조 해석시 원심력 영향이 주의깊게 고려되었다. 극심한 온도 분포에 따른 열하중 또한 터빈 블레이드-디스크에 작용하는 외부하중으로 고려되었다. MSC/NASTRAN DMAP Alter를 이용한 3차원 유한요소법이 주기 대칭 구조 해석에 적용되었다. 회전 속도에 따른 구조 동특성의 고찰을 위하여 블레이드간 위상차가 고려되었다. 수치해석을 통하여 원심력과 열하중이 터빈 블레이드-디스크에 미치는 영향을 고찰하였다.

• 한국환경과학회지
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• 제20권8호
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• pp.929-942
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• 2011

A novel conductivity technique was developed to detect penetration depth of the vessel fluid into the feedpipe. For a given reactor geometry, critical agitator speeds were experimentally determined at the onset of feedpipe backmixing using Rushton 6 bladed disk turbine (6BD) and high efficiency axial flow type 3 bladed (HE-3) impellers. The ratio of the feedpipe velocity to the critical agitator speed ($v_f/v_t$) was constant for either laminar or turbulent feedpipe flow regimes. Compared to the results of fast competitive reaction, feedpipe backmixing had to penetrate at least one feedpipe diameter into the feedpipe to significantly influence the yield of the side product. However, higher $v_f/v_t$ than that for L/d = 0 (position at the feedpipe end) of the conductivity technique is recommended to completely eliminate feedpipe backmixing in conservative design criteria. The conductivity technique was successful in all feedpipe flow conditions of laminar, transitional and turbulent flow regimes.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2008년도 추계학술대회논문집
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• pp.253-253
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• 2008

The main purpose of this study is to identify the vibrational characteristics for the LP blades of Korean standard fossil power plants. Modal tests for the 6 stage blade with boundary condition in which the root of blades are constrained with the disk were conducted, and FE analysis was also did with the same boundary condition. The steady-stress and modal analyses for the coupled bladed-disk system of LP turbine stages were completed. The dynamic analysis and fatigue analysis were followed to diagnose the integrity of LP turbine blades.

• 한국항공우주학회지
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• 제32권3호
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• pp.58-65
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• 2004

유한요소법을 이용하여 액체 로켓 엔진 터보 펌프 터빈의 천이 열전달 및 구조 해석이 수행되었다. 해석 모델은 3차원 8절점 등매개변수 솔리드 요소로 구성되었으며, 전체 모델의 1/80만이 해석되었다. 열 스파이크를 포함하는 시동 조건과 정상상태에서의 하중이 고려되었다. 블레이드 면 위의 열전달 계수는 상용 열유동 해석 프로그램인 Fluent를 이용하였다. 개발된 유한 요소 코드를 이용하여 시동 및 정상상태에서 천이 열전달 응답을 구하였다. 또한, 원심력과 열하중이 가해질 때, 최대 응력 및 슈라우드의 변위를 구하였다.

• 한국유체기계학회 논문집
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• 제7권5호
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• pp.20-28
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• 2004

Static and dynamic structural analyses of a turbine bladed-disk for a liquid rocket turbopump are performed to investigate the safety level of strength and vibration at design point. During operation, turbopump is exposed to various external loads. Therefore, the effects of them should be carefully considered and properly modeled. First, due to the high rotational speed of the turbopump, effects of centrifugal forces are considered in the structural analysis. Thermal load caused by severe temperature differences is also considered. A three dimensional finite element method (FEM) is used for linear and nonlinear structural analyses with modified Newton-Raphson iteration method. After the nonlinear solution is obtained from the structural analysis, dynamic characteristics are obtained as a function of rotational speed from the linearized eigenvalue analysis at an equilibrium position. From the analysis results, characteristics of stress distribution and vibration were thoroughly examined and investigated.