• Title/Summary/Keyword: lubrication seal

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Air Jet Effect on Performance Improvement of Non-Contact Type Seals for Oil Mist Lubrication Systems (공기분사가 오일미스트 윤활 시스템용 비접촉 시일의 성능 향상에 미치는 영향)

  • Na, Byeong-Cheol;Jeon, Gyeong-Jin;Han, Dong-Cheol
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.24 no.9 s.180
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    • pp.2159-2166
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    • 2000
  • Recently, high performance machining center requires special type of sealing mechanism that prevent a leakage of oil jet or oil mist lubrication system. Sealing of oil-air mixture plays important r oles to have an enhanced lubrication for performance machining center. Current work emphasizes on investigations of the air jet effect on the protective collar type labyrinth seal. To improve sealing capabilities of conventional labyrinth seals, air jet is injected against the leakage flow. In this study, an adapted model is introduced to improve sealing capability of conventional non-contact type seals. It has a combined geometry of a protective collar type and an air jet type. Both of a numerical analysis by CFD (Computational Fluid Dynamics) and experimental measurements are carried out to verify sealing improvement. The sealing effects of the leakage clearance and the air jet magnitude aic studied in various parameters. Gas or liquid has been used as a working fluid for most of nori-contact types seals including the labyrinth seal. However, it is more reasonable to regard two-phase flows because oil mist or oil jet are used for high performance spindle's lubrication. In this study, working fluid is regarded as two phases that are mixed flow of oil and air phase. Both of turbulence and compressible flow model are also introduced in a CFD analysis to represent an isentropic process. Estimation of non-leaking property is determined by amount of pressure drop in the leakage path. Results of pressure drop in the experiment match reasonably to those of the simulation by introducing a flow coefficient. Effect of the sealing improvement is explained as decreasing of leakage clearance by air jetting. Thus, sealing effect is improved by amount of air jetting even though clearance becomes larger

Characteristics of Leakage and Rotordynamic Coefficients for Annular Seal with Honeycomb/Smooth Land (Honeycomb/Smooth 표면을 갖는 비접촉 환상 실의 특성해석)

  • Ha, Tae-Woong
    • The KSFM Journal of Fluid Machinery
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    • v.5 no.4 s.17
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    • pp.40-46
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    • 2002
  • An honeycomb/smooth land seal alternating with the honeycomb seal is suggested for structural enhancement in high pressure turbomachinery. Governing equations are derived for an honeycomb/smooth land annular gas seal based on Hirs' lubrication theory and Moody's friction factor model for smooth land and empirical friction factor model for honeycomb land. By using a perturbation analysis and a numerical integration method, the governing equations are solved to yield leakage and the corresponding dynamic coefficients developed by the seal. Theoretical results show that the leakage increases and rotordynamic stability decreases as increasing the length of smooth land part in the honeycomb/smooth land seal.

Finite Element Analysis for Performance Evaluation of the Seal in a Universal Joint Bearing (유니버설 조인트 베어링용 시일의 성능평가를 위한 유한요소해석)

  • Kim, Tae-Wan;Moon, Suk-Man;Koo, Young-Pil;Cho, Yong-Joo
    • Journal of the Korean Society for Precision Engineering
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    • v.18 no.9
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    • pp.140-146
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    • 2001
  • Seals in a universal joint bearing are important components reinforcing lubrication performance by holding lubricant and preventing infiltration of dust, moisture, etc.. There is a great difference in seal performance according to seal shape and bonding position. Therefore, in this study, as for both the lip type seal and the O-ring type seal, FE analysis is conducted using Mooned-Rivlin Model. The results show that O-ring type seal does not have any effect of misalignment angle compared with lib type seal, which is more profitable.

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Analysis characters of distortion of inclined mechanical face seal (경사진 기계평면시일의 변형거동 특성 해석)

  • 조승현;고영배;김청균
    • Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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    • 2001.11a
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    • pp.341-349
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    • 2001
  • Heat distortion of the non-contacting mechanical face seal is affected by friction heat between primary seal and seal sheet. The fluid or gas in mechanical face seal maintains operating gap, cooling friction heat and lubricates at the face of seal. So we designed face of seal for inclined face. inclined face of seal improves fluid or gas flow at the face of seal and it increases circumferential velocity at outer radius of the seal so temperature of the seal is decreased by low heat transfer coefficient at there. In this paper, inclined face seal are analysed numerically using finite element method for proof improve inclined face seal performance. Angle of the incline face used for FEA is from 50$^{\circ}$to 90$^{\circ}$and for explaining the effects of inclined face in seal, we get temperature, face distortion, and stress in the seal with variable operating gap and rotating speeds. Result of analysis shows that angle of the incline face is 60$^{\circ}$come to good thermal distortion characteristics.

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Groove Design of a Gas Seal Including Friction Heatings (마찰열을 고려한 가스시일의 그루브 설계)

  • 김청균;조승현;고영배;차백순
    • Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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    • 2000.06a
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    • pp.201-210
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    • 2000
  • The noncontacting groove end face seal is one of various approaches to sealing gases with a single seal. Gas pumped into groove maintains operating gap and lubricates between primary ring and mating ring. So it removes heat and decreases face wear. In this paper, K-type and T-type grooved seals have been analyzed numerically using the finite element method. It explains the effects of groove shapes in gas seals along rotating speeds with a temperature gradient, face distortion, stress and so on. The calculated FEM results show the operating gap and rotating speed are strongly related to the leakages of a gas seal and that T-type groove seal shows a good thermal performance compared to K-type groove seal.

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Characteristics of Leakage and Rotordynamic Coefficients for Annular Seal with Multi-Land (이종 표면을 갖는 실의 특성해석)

  • Ha, Tae Woong
    • 유체기계공업학회:학술대회논문집
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    • 2002.12a
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    • pp.447-452
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    • 2002
  • An honeycomb/smooth land seal alternating with the honeycomb seal is suggested for structural enhancement in high pressure turbomachinery. Governing equations are derived for an honeycomb/smooth land annular gas seal based on Hirs' lubrication theory and Moody's friction factor model for smooth land and empirical friction factor model for honeycomb land. By using a perturbation analysis and a numerical integration method, the governing equations are solved to yield leakage and the corresponding dynamic coefficients developed by the seal. Theoretical results show that leakage is increasing and rotordynamic stability is decreasing as increasing the length of smooth land part in the honeycomb/smooth land seal.

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FEM Analysis for Performance Evaluation of Seal in Universal Joint Bearing (유니버설 조인트 베어링용 Seal의 성능평가를 위한 유한요소해석)

  • 김태완;문석만;구영필;조용주
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2000.11a
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    • pp.571-574
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    • 2000
  • Seals in universal joint bearing are a important component reinforcing lubrication performance by holding a lubricant and preventing infiltration of dust, moisture, etc. There is a great difference in seal performance according to seal shape and bonding position. Therefore, in this study, as for the lib type seal and O-ring type seal, FEM analysis are conducted using Mooney-Rivlin Model. The results are indicate that O-ring having higher contact stress and larger contact area than lib type is more profitable.

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An Effect of Shaft Speed on the Leakage in a labyrinth Seal (Labyrinth Seal 내 누수량에 미치는 축 회전속도의 영향)

  • 이관수;이상욱;김창호
    • Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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    • 1990.06a
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    • pp.73-91
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    • 1990
  • Incompressible turbulent flow in a single cavity of the stepped multi-cavity labyrinth seal is numerically analyzed to investigate an effect of the shaft speed on the leakage. SIMPLER algorithm is used to solve governing equations, and low-Reynolds k-$\varepsilon$ turbulence model as outlined by Launder and Sharma is adopted to predict turbulent flow. Pressure drops for the cavity with and without the groove are evaluated for four different Reynolds numbersand three different shaft speeds.

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공기분사를 이용한 라비린스 시일이 성능개선방안 연구

  • 나병철;전경진;한동철
    • Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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    • 1996.04b
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    • pp.153-157
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    • 1996
  • A restrict jetting air is applied against leakage flow to improve a sealing performance of conventional labyrinth seal. A CFD analysis and sealing experiment are introduced to evaluate a sealing performance of applied model. The base of enhanced sealing is explained as a reducing clearance effect by jetting air. As a result, the applied model can improve the sealing performance of labyrinth seal in spite of the wide leakage clearance.

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Hydrodynamic forces of impeller shroud and wear-ring seal on centrifugal pump (고성능 원심펌프에서 임펠러 시라우드 및 마모 시일의 유체가진력 해석)

  • Ha, Tae-Woong
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.22 no.1
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    • pp.102-110
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    • 1998
  • The analysis of lateral hydrodynamic forces in the leakage path between a shrouded pump impeller through wear-ring seal and its housing is presented. Governing equations are derived based on Bulk-flow and Hirs' turbulent lubrication model. By using a perturbation analysis and a numerical integration method, governing equations are solved to yield leakage and rotordynamic coefficients of force developed by the impeller shroud and wear-ring seal. The variation of rotordynamic coefficients of pump impeller shroud and wear-ring seal is analyzed as parameters of rotor speed, pressure difference, shroud clearance, wear-ring seal clearance, and circumferential velocity at the entrance of impeller shroud for a typical multi-stage centrifugal pump.