• 한국정밀공학회지
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• 제15권4호
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• pp.76-82
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• 1998

Sealing an oil-air mixture plays important roles to have an enhanced lubrication for high speed spindle. Current work is emphasized on the investigation of the air jet effect on the protective collar type labyrinth seal. To improve the sealing capability of conventional labyrinth seal, air jet is injected against through the leakage flow. It has a combined geometry of a protective collar type and an air jet type. In this study, both of a numerical analysis by CFD(Computational Fluid Dynamics) and experimental measurements are carried out to verify sealing improvement. Both of the turbulence and the compressible flow model are introduced in CFD analysis. The sealing effect of the leakage clearance and the air jet magnitude are studied for various parameter in the experiment. The results of pressure drop in the experiment match reasonably to those of the simulation by introducing a flow coefficient. Effects of sealing improvement are explained as decreasing of effective leakage clearance by air jetting. Thus, sealing effect is improved by amount of air jetting even though clearance becomes larger.

• 한국소음진동공학회논문집
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• 제11권8호
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• pp.322-330
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• 2001

The stability and the leakage performance of turbo pump unit seals supported by elastic-ring ball bearings are Investigated for the Improvement of onset speed of instability(OSI). The numerical analysis of floating ring seal in consistence with its geometry and operating conditions is executed with detailed comparison of various seal types. The results show that the floating ring seal has superior performance in terms of rotordynamic salability compared to the ocher type seals while it shows slightly inferior leakage performance. To Improve the leakage performance. floating ring seal could be combined with hole Pattern damper or labyrinth seal surface.

• 대한기계학회논문집A
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• 제24권9호
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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

• Nuclear Engineering and Technology
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• 제53권10호
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• pp.3438-3448
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• 2021

Dynamic seals are one of the critical components of Absorber Rod Drive Mechanism of Fast Breeder Reactors, requiring separate experimental development. Their significance can't be overemphasized considering that the availability and re-usability of Control Rod Drive Mechanisms of Fast Breeder Test Reactor is governed by the failure rate of dynamic seals (bellows). For prototype and subsequent Fast Breeder Reactors in India, choice of the dynamic seal is changed to an in-house designed & developed labyrinth type V-ring seal. The present work is related to the numerical investigations carried out to gain insights into the sealing mechanism and the thermal behaviour of these seals. The results indicate that the seal geometry is very important for obtaining optimum performance. By changing the geometry of the present seal, performance enhancement by more than 50% in important indices is obtained. Further, the results point out that caution shall be exercised when the seal material & its operating temperature are changed. Also, the numerical model developed in this study will be useful for developing more robust dynamic seals in future.

• 한국산학기술학회논문지
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• 제18권5호
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• pp.657-666
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• 2017

본 연구에서는, 50인치 이상 대형 텔레비전의 높낮이의 마찰을 줄이기 위한 요인 분석이 실시되었다. 첫째는 피스톤 로드의 정확한 위치 제어를 위한 관형 전단면 제어에 대한 것이다. 여기서 관형 오리피스 전단면과 미로형 오리피스 전단면이 비교되었다. 두 번째 연구는 가스 씰 립 기술에 의한 마찰력 줄이기가 시행되었다. 세 번째는 실린더의 체적의 보상을 위한 주변장치가 피스톤 로드의 체적을 압축함으로서 세부사양을 결정하고 체적 보상 실험을 수행하는 것이다. 이로 인한 연구 결과들은 다음과 같다. 첫째는 CAE 및 실험적 고려를 통한 관형과 미로형 사이의 오리피스 전단면에 있어서, 미로형 오리피스의 전단면이 마찰을 줄이는데 뛰어났다. 둘째는 가스 씰 립 기술에서, 중공 로드의 실험 결과에서 외경 20 mm, 내경 8 mm의 직경을 가지는 것이 30 킬로그램을 가정한 50인치 이상의 텔레비전에 가장 적합한 것으로 확인되었다. 셋째는 사양결정과 체적 보상 실험을 위한 체적 보상의 안전성 문제와 성능의 총체적 고려사항 결과 중공로드 외경 8 mm, 내경 4 mm와 리벳 시스템이 결정되었다. 마지막으로, 300 mm의 이동거리에서는 관형, 미로형 오리피스에 있어 직경 0.4~0.6의 오리피스에서는 미로형 오리피스가 발견되지 않았다.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2017년도 제48회 춘계학술대회논문집
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• pp.572-582
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• 2017

공기 흡입 엔진을 개발하기 위해서는 지상 시험을 통한 추력 측정이 반드시 필요한데, 공기 흡입 엔진은 추력 측정 장치에서 측정된 값 이외에도 엔진 흡입구로 들어오는 공기 유동에 의한 힘을 고려하여 총추력을 계산해야 한다. 또한 다분력 추력 측정 장치를 활용하여 요와 피치 방향의 측추력도 정확하게 측정하고 분석할 수 있어야 한다. 래버린스 씰 격리, 1축 총추력 계산, 다분력 추력 측정 장치 개발, 측추력 분석 등의 일련 과정을 통해 공기 흡입 엔진의 총추력을 정밀하게 추정하여 엔진 성능을 보다 정확하게 평가할 수 있게 하였다.

• 한국추진공학회지
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• 제22권3호
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• pp.97-108
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• 2018

공기 흡입 엔진을 개발하기 위해서는 지상 시험을 통한 추력 측정이 반드시 필요한데, 공기 흡입 엔진은 추력 측정 장치에서 측정된 값 이외에도 엔진 흡입구로 들어오는 공기 유동에 의한 힘을 고려하여 총추력을 계산해야 한다. 또한 다분력 추력 측정 장치를 활용하여 요와 피치 방향의 측추력도 정확하게 측정하고 분석할 수 있어야 한다. 래버린스 씰 격리, 1축 총추력 계산, 다분력 추력 측정 장치 개발, 측추력 분석 등의 일련 과정을 통해 공기 흡입 엔진의 총추력을 정밀하게 추정하여 엔진 성능을 보다 정확하게 평가할 수 있게 하였다.

• 한국유체기계학회 논문집
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• 제12권5호
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• pp.47-53
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• 2009

A rotordynamic and detailed stability analysis in accordance with API 617 standard were performed with a turbo-compressor, which is one of key rotating machinery in refinery, petroleum, and power plants. The system is composed of rotor shaft, impeller, sleeve hub, balance drum, and coupling hub. The rotor system is supported by tilting pad bearings, which has 5 pads and pad on loading condition. The rotordynamic analysis specified by API 617 includes the critical speed map, mode shape analysis, Campbell diagram, unbalance response analysis, and stability analysis. In particular, the specifications of stability analysis consist of a Level 1 analysis that approximates the destabilizing effects of the labyrinth seals and aerodynamic excitations, and Level 2 analysis that includes a detailed labyrinth seal aerodynamic analysis. The results of a rotordynamic analysis and stability analysis can evaluate the operating compressor health and can be utilized as a guide of its maintenance, repair and trouble solution.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 추계학술대회
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• pp.1715-1720
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• 2004

This paper presents the characteristics of internal clearances for the interstage of blades and shaft gland seals on the steam turbine which are installed in tandem compound. Internal clearances was changed when the rotor turned in the cylindrical sleeve bearing due to the generation of oil film wedge. This presented concern is very useful to prevent the rubbing damage of seal edge between the fixed and moving parts in steam turbine due to the misalignment at the rotating and stationary parts. This method is applied for the unbalanced clearances distribution to the left and right sides in the turbine casing. A considerable amount of unbalanced clearances distribution trend is determined according to the rotating speed of rotor, size and type of proceeding bearing, oil viscosity, surface roughness of bearing and shaft, oil temperature, oil pressure and bearing load.