• Title/Summary/Keyword: 회전체동역학적 특성계수

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Rotordynamic Analysis of a Labyrinth Seal Using the Moody's Friction-Factor Model (Moody 마찰계수식을 사용한 래버린스 실의 회전체 동역학적 해석)

  • Ha, Tae Woong
    • The KSFM Journal of Fluid Machinery
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    • v.2 no.3 s.4
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    • pp.52-58
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    • 1999
  • The leakage and rotordynamic coefficients of see-through type gas labyrinth seals are determined using a two-control-volume-model analysis with Moody's wall-friction-factor formula which is defined with a large range of Reynolds number and relative roughness. Jet flow theory are used for the calculation of the recirculation velocity in the cavity. For the reaction force from the labyrinth seal, linearized zeroth-order and the first-order perturbation equations are developed for small motion about a centered position. The leakage and rotordynamic coefficient results of the present analysis are compared with Scharrer's theoretical analysis using Blasius' wall-friction-factor formula and Pelletti's experimental results. The comparison shows that the present analysis using Moody's wall-friction-factor formula and Scharrer's theoretical analysis using Blasius' wall-friction-factor formula give the same results for a smooth seal surface and the range of Reynolds number less than $10^5$.

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Rotordynamic and Leakage Analysis for Eccentric Annular Seal (편심된 펌프 실의 누설 및 회전체동역학적 해석)

  • Ha, Tae-Woong
    • The KSFM Journal of Fluid Machinery
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    • v.4 no.2 s.11
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    • pp.15-21
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    • 2001
  • Basic equations and their solution procedure we derived for the analysis of an annular pump seal in which the rotor has a large static displacement from the centered position. The Bulk-flow is assumed for a control volume set in the seal clearance and the flow is assumed to be completely turbulent in axial and circumferential direction. Moody's wall-friction-factor formula is used for the calculation of wall shear stresses in the control volume. For the reaction force developed by the seal, linearized zeroth-order and first-order perturbation equations are developed for small motion about an eccentric position. Flow variables are expanded by using Fourier series for the solution procedure. Integration of the resultant first-order pressure distribution along and around the seal defines the 12 elements of rotordynamic coefficients of the eccentric annular pump seal. The results of leakage and rotordynamic coefficients aye presented and compared with the Marquette's experimental results and the San Andres' theoretical analysis.

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Rotordynamic Analysis of Compressor Labyrinth Seals (압축기용 라비린스 실의 동특성 해석)

  • 하태웅;이안성
    • Journal of KSNVE
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    • v.8 no.5
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    • pp.849-855
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    • 1998
  • An analysis of lateral hydrodynamic forces of compressor labyrinth seals is presented. Basic equations are derived using a two-control-volume model for compressible flow. Blasius' wall friction-factor formula and jet flow theory are used for the calculaton of wall shear stresses and recirculation velocity in the cavity. Linearized zeroth-order and first-order perturbation equations are developed for a small motion about the centered position by expansion in the eccentricity ratio. Integraton of the resultant first-order pressure distribution over the seal defines the rotordynamic coefficients. As an application a rotordynamic analysis of the balance drum labyrinth seal found in an ethylene regrigeration copmressor is carried out. The rotordynamic characteristic results of the labyrinth seal are presented and compared with other types of seals, honeycomb seal and smooth seal.

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Leakage and Rotordynamic Analysis of High Pressure Floating Ring Seal in Turbo Pump (터보 펌프 고압 후로팅 링 실의 누설량 및 회전체 동역학적 특성 해석)

  • Ha, Tae Woong;Lee, Yong-Bok;Kim, Chang-Ho
    • The KSFM Journal of Fluid Machinery
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    • v.4 no.3 s.12
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    • pp.29-38
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    • 2001
  • The floating ring seal has the ability of minimizing clearance without the rubbing phenomenon. It is often used in the turbo pump units of liquid rocket engines due to its superior leakage performance. The exact prediction of the lock-up position of the floating ring, the leakage performance, and the rotordynamic coefficients of the seal is necessary to evaluate the rotordynamic performance of the turbo pump unit. The governing equations(which are based on the Bulk-flow Model) we solved by the Fast Fourier Transform method. The lock-up position, leakage flow rate, and rotordynamic coefficients are evaluated according to the geometric parameters of the floating ring seal.

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Labyrinth Seal Design Considering Leakage Flow Rate and Rotordynamic Performance (누설유량과 회전체동역학적 성능을 고려한 래버린스 씰 설계)

  • Minju Moon;Jeongin Lee;Junho Suh
    • Tribology and Lubricants
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    • v.39 no.2
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    • pp.61-71
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    • 2023
  • This study proposes a procedure for designing a labyrinth seal that meets both leakage flow rate and rotordynamic performance criteria (effective damping, amplification factor, separation margin, logarithmic decrement, and vibration amplitude). The seal is modeled using a one control volume (1CV) bulk flow approach to predict the leakage flow rate and rotordynamic coefficients. The rotating shaft is modeled with the finite element (FE) method and is assumed to be supported by two linearized bearings. Geometry, material and operating conditions of the rotating shaft, and the supporting characteristics of the bearings were fixed. A single labyrinth seal is placed at the center of the rotor, and the linearized dynamic coefficients predicted by the seal numerical model are inserted as linear springs and dampers at the seal position. Seal designs that satisfy both leakage and rotordynamic performance are searched by modifying five seal design parameters using the multi-grid method. The five design parameters include pre-swirl ratio, number of teeth, tooth pitch, tooth height and tooth tip width. In total, 12500 seal models are examined and the optimal seal design is selected. Finally, normalization was performed to select the optimal labyrinth seal designs that satisfy the system performance requirements.

Dynamic response analysis of vertical pumps (입형펌프의 동적 응답해석)

  • 양보석;김원철;임우섭;권명래
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.13 no.3
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    • pp.362-372
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    • 1989
  • It is important in design of vertical pumps to consider external excitation in addition to rotor vibration due to unbalance. In this study, a model of a vertical pump was developed for the analysis of its dynamic response. The vertical pump was modeled with lumped masses and springs which represent multi-cylindrical and rotor structure. A dynamic simulation program was developed and numerical calculation on the above mentioned problems were carried out.