• Title/Summary/Keyword: Annular seal

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The Effects of Centrifugal Stress on Seal Dynamics (시일 동특성에 미치는 원심응력의 영향에 관한 연구)

  • 양보석
    • Tribology and Lubricants
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    • v.5 no.1
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    • pp.64-68
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    • 1989
  • The dynamic characteristics of the annular pressure seal employed in pump have been theoretically deduced with consideration of the effects of elastic deformation due to the centrifugal stress. The deformation of the shaft is governed by the linear theory of elasticity. The results derived herein considering the elastic deformation are compared with the previously published author's results in the stiffness and damping coefficients.

Prediction of Combination-Type-Staggered-Labyrinth Seal Leakage Using CFD (CFD를 사용한 복잡한 형상을 갖는 래버린스 실의 누설량 예측)

  • Ha Tae-Woong
    • Tribology and Lubricants
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    • v.22 no.2
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    • pp.66-72
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    • 2006
  • Leakage reduction through annular type labyrinth seals of steam turbine is necessary for enhancing their efficiency and the precise prediction method of seal leakage is needed. In this study, numerical analysis for leakage prediction of the combination-type-staggered-labyrinth seal has been carried out using FLUENT 6 which is commercial CFD (Computational Fluid Dynamics) code based on FVM (Finite Volume Method) and SIMPLE algorism. The present CFD results are verified with the theoretical analysis based on Bulk-flow concept which has been mainly used in predicting seal leakage. Comparing with the result of Bulk-flow model analysis, the leakage result of CFD analysis shows good agreement within 7.1% error.

Leakage Analysis and Design Modification of the Combination-Type-Staggered-Labyrinth Seal (누설량 저감을 위한 래버린스 실의 설계개선 및 해석)

  • Ha, Tae-Woong
    • Tribology and Lubricants
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    • v.23 no.2
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    • pp.43-48
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    • 2007
  • Leakage reduction through annular type labyrinth seals of steam turbine is necessary for enhancing their efficiency. In this study, modified geometry of the original combination-type-staggered-labyrinth seal has been suggested and numerical analysis for leakage prediction has been carried out for the modified-combination-type-staggered-labyrinth seal both based on bulk-flow model and using the CFD code FLUENT. The theoretical analysis based on bulk-flow model yields leakage reduction of the modified combination type staggered labyrinth seal by about 11%. Comparing with the result of Bulk-flow model analysis, the leakage result of CFD analysis shows reasonable agreement within 9.8% error.

Leakage and Rotordynamic Analysis of Spiral-Grooved Pump Seal Based on Three-Control-Volume Theory (나선 홈 펌프 실의 누설 및 로터다이내믹 해석)

  • Ha, Tae-Woong;Lee, An-Sung
    • The KSFM Journal of Fluid Machinery
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    • v.6 no.1 s.18
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    • pp.14-22
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    • 2003
  • In this paper the leakage prediction md rotordynamic analysis of an annular seal with a smooth rotor and spiral-grooved stator is performed. For the development of a theoretical model, the three-control-volume analysis of the circumferentially-grooved seal is expanded by considering pressure reduction due to the pumping effect of spiral groove and pressurized flow through the spiral groove. Validation on the present analysis is achieved by comparisons with available experimental data. For the leakage prediction the present analysis generally shows a reasonable agreement with experimental results. Rotordynamic coefficients for rotor speed with spiral angles show same trend, but the magnitudes of rotordynamic coefficients yield differences between analysis and experimental results.

Characteristic Analysis of Spiral-Grooved Pump Seal (나선 홈 펌프 시일의 특성 해석)

  • Ha, Tae-Woong;Lee, An-Sung
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2002.11b
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    • pp.799-804
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    • 2002
  • In this paper the leakage prediction and rotordynamic analysis of an annular seal with a smooth rotor and spiral-grooved stator are performed. For developing a theoretical model, the three-control-volume analysis of the circumferentially-grooved seal is expanded by considering pressure reduction due to the pumping effect of spiral groove and pressure flow through the spiral groove. Results by the present analysis are compared with available experimental data. For leakage the analysis results generally show a reasonable agreement to the experimental results. For rotordynamic coefficients the analysis results show the same trend as the experimental results for rotor speed with spiral angles, but their magnitudes show somewhat large deviations.

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Characteristic Analysis of Spiral-Grooved Pump Seal (나선 홈 펌프 시일의 특성 해석)

  • Ha, Tae-Woong;Lee, An-Sung
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2002.11a
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    • pp.379.1-379
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    • 2002
  • In this paper the leakage prediction and rotordynamic analysis of an annular seal with a smooth rotor and spiral-grooved stator are performed. For developing a theoretical model, the three-control-volume analysis of the circumferentially-grooved seal is expanded by considering pressure reduction due to the pumping effect of spiral groove and pressure flow through the spiral groove. Validation to the present analysis is achieved by comparisons with available experimental data. (omitted)

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시일의 마멸로 인한 다단터빈펌프의 위험속도 변화

  • Kim, Yeong-Cheol;Lee, Dong-Hwan;Lee, Bong-Ju
    • 유체기계공업학회:학술대회논문집
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    • 1998.02a
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    • pp.203-209
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    • 1998
  • Rotordynamic analysis of a multistage turbine pump using finite element method is performed to investigate the effects of seal wear on Its system behavior. Stiffness and damping coefficients of the 2-axial grooved bearing are obtained as functions of rotating speed. Stiffness and damping coefficients of plane annular seals are calculated as functions of rotating speed as well as seal clearance. As the clearance of seals become larger, these stiffness and damping coefficients decrease drastically so that there can be significant changes in whirl natural frequencies and damping characteristics of the pump rotor system. Although a pump is designed to operate with a sufficient seperation margin from the 1st critical speed, seal wear due to long operation may cause a sudden increase in nitration amplitude by resonance shift and reduce seal damping capability.

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Improvement on Prediction of Circumferential-Groove-Pump Seal with CFD Analysis (CFD를 사용한 평행 홈 펌프 시일의 해석 개선)

  • Ha, Tae-Woong
    • Tribology and Lubricants
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    • v.24 no.6
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    • pp.291-296
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    • 2008
  • In order to improve the leakage prediction and rotordynamic analysis of an annular seal with a smooth rotor and circumferentially grooved stator, CFD analysis using FLUENT has been performed to determine the groove penetration angle a which is the angle of separation line between control volumes II and III in groove section of Ha and Lee's three-control-volume theory. Validation to the present analysis using new penetration angle determined by the CFD analysis is achieved by comparisons with the results of published Ha and Lee's analysis. For the leakage prediction the present analysis shows slight improvement and CFD results yields the best. Direct damping and cross-coupled stiffness coefficients are predicted better to the experimental ones. However, direct stiffness coefficient is predicted worse.

A Rotordynamic Analysis of Circumferentially-Grooved Pump Seals Based on a Three-Control-Volume Theory

  • Ha, Tae-Woong;Lee, An-Sung
    • Journal of Mechanical Science and Technology
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    • v.14 no.3
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    • pp.261-271
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    • 2000
  • In this paper the leakage prediction and rotordynamic analysis of an annular seal with a smooth rotor and circumferentially grooved stator are performed based on a three-controlvolume theory. The present analysis is validated by comparing with the experimental data of Iwatsubo and Sheng and theoretical results suggested by Marquette and Childs. For the leakage prediction the present analysis shows a good agreement with Marquette and Childs' result and a qualitation agreement with Iwatsubo and Shengs' experimental data. Direct and cross-coupled stiffness coefficients show closer agreement with the experimental values than those of Marquette and Childs. However, direct damping coefficient shows greater discrepancy from the experimental value than Marquette and Childs'.

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A Study on The Wear Process and Wear Mechanism of the Alumina Ceramics with Different Alumina Purity (순도를 달리한 알루미나 세라믹스의 마멸과정 및 이의 기구에 관한 연구)

  • 전태옥;진동규
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.18 no.12
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    • pp.3404-3412
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    • 1994
  • The present study was undertaken to investigate the dry wear process and wear mechanism of the alumina ceramics in the purity variation which are used for the mechanical seal, roll, liner and dies. The wear test was carried out under different experimental condition using the wear testing device and in which the annular surface rubbed on dry sliding condition various sliding speed, contact pressure and sliding distance. In case of alumina purity 95%, there was speed range which wear loss increased rapidly owing to enlargement of heat impact force and temperature rise of wear surface. According as the alumina purity increased, wear loss decreased but alumina purity 85% with much void and defect had the most wear loss than any other alumina purity. The friction coefficient of sliding initial stage of wear curves has a large value but according to increase of sliding distance, it decreased owing to drop of the shear strength of wear surfaces.