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스러스트 래버린스 실을 배면에 갖는 원심형 임펠러의 축력 해석
박준혁(Jun Hyuk Park),김태호(Tae Ho Kim) 한국트라이볼로지학회 2021 한국트라이볼로지학회지 (Tribol. Lubr.) Vol.37 No.1
This study describes the effects of a thrust labyrinth seal applied to the backside of a centrifugal impeller on the axial thrust force for high speed turbomachinery. The bulk flow model using Neumann’s equation calculates the seal cavity pressures and leakage flow rate of the thrust labyrinth seal based on three configurations: teeth-on-rotor (TOR), teeth-on-stator (TOS), and interlocking labyrinth seal (ILS). Prediction results show that the ILS is superior to the TOR and TOS in terms of leakage flow rate. A mathematical model of a centrifugal impeller with a thrust labyrinth seal on its backside calculates the force components corresponding to the impeller inlet, shroud, impeller backside outer, backside seal, and backside inner pressures. A summation of the force components renders the total axial thrust force acting on the centrifugal impeller. The Newton-Raphson numerical scheme iteratively calculates the pressures and leakage flow rate through the impeller wall gap. The prediction results reveal that the leakage flow rate and total axial thrust force increase with rotor speed, and the ILS significantly decreases the leakage flow rate, whereas it slightly increases the axial thrust force when compared to TOR and TOS. Increasing the seal clearance causes an increase in the leakage flow rate and a slight decrease in the axial thrust force with the ILS.
CFD를 사용한 스팀터빈용 각이 진 패킹 링 실의 누설량 예측
하태웅(Tae Woong Ha),강정현(Jung Hyun Kang) 한국트라이볼로지학회 2009 한국윤활학회지(윤활학회지) Vol.25 No.5
An angled labyrinth seal is used for the diaphragm-packing-ring seal design of steam turbine due to its leakage reduction characteristic. CFD analysis using FLUENT has been performed to predict leakage and determine an optimum slanted angle which yields the best leakage reduction. Results show that the optimum value of slanted angle is -30° independent of number of labyrinth teeth, inlet pressure, and tooth height to pitch ratio. 3D CFD analysis has been performed for predicting leakage of the angled labyrinth seal. Comparing with the result of 2D CFO analysis, 3D CFD analysis shows 1.4% smaller.
하태웅(Tae Woong Ha),이용복(Yong-Bok Lee),김승종(Seung-Jong Kim) 한국유체기계학회 2006 유체기계 연구개발 발표회 논문집 Vol.- No.-
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 mode and using the CFD code of 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.
석희수(Hee Soo Seok),하태웅(Tae Woong Ha) 한국트라이볼로지학회 2009 한국트라이볼로지학회지 (Tribol. Lubr.) Vol.25 No.3
Precise leakage prediction for annular type seals of turbomachinery is necessary for enhancing their efficiency and various prediction methods have been developed. As the seal passage is designed intricately, the analysis based on Bulk-flow concept which has been mainly used in predicting seal leakage is limited. In order to improve the seal leakage prediction, full Navier-Stokes Equations with turbulent model derived in the seal flow passage have to be solved. In this study, 3D CFD (Computational Fluid Dynamics) analysis has been performed for predicting leakage of various non-contact type anular seals using FLUENT. Compared to the results by Bulk-flow model analysis, experiment, and 2D CFD analysis, the result of 3D CFD analysis shows improvement in predicting seal leakage, especially for the parallel grooved pump seal.
1차원 모델을 이용한 회전하는 사다리꼴 이빨 래버린스 실의 누설 저감 성능 예측
권정우,안준 한국유체기계학회 2024 한국유체기계학회 논문집 Vol.27 No.3
The sealing performance of the labyrinth seal applied to the gas turbine secondary passage system was predicted using Flomaster, a one-dimensional code. The rotation effect was predicted by applying clearance change and swirl models, respectively. It is difficult to obtain data on clearance changes due to rotation, and when applied, the leakage prediction also showed an error of up to 10%. The rotation effect was appropriately predicted with an error within 4% using the swirl model. Even under high temperature conditions, the sealing performance of the labyrinth seal was well predicted by the swirl model without separate correction for clearance.
LNG 펌프의 누설 유량 최소화를 위한 래버린스 실 형상의 수치적 연구
곽용준,김성환,조윤제,장경식,백현창 한국유체기계학회 2022 한국유체기계학회 논문집 Vol.25 No.4
In the submersible pump used in an LNG cargo, the leakage flow (gap flow) occurs between the pump rotor and the casing, and the pump efficiency decreases. The labyrinth-shaped pattern is applied between these gaps to decrease the leakage flow, which is called Labyrinth Seal. This research studied the difference in flow characteristics when liquefied methane which accounts for most LNG composition passes through labyrinth seals of different shapes using computational fluid dynamics (CFD). Four shape variables were considered: clearance size(s), cavity width(b), cavity height(g), and number of cavity(z). Parametric study was performed by changing only the input value of one variable without changing other variables within a limited range. As the gap of the labyrinth seal increased, the leakage flow rate increased. But the effect of the cavity-related variables was different. As a result of analyzing the effects of three cavity variables using full factorial design, they were found to be almost independent of each other. As the cavity width and number increase, the leakage flow rate decreases linearly. And the cavity height has a maximum leakage flow rate at one point, but has the smallest influence among all variables.
가스터빈 압축기용 허니컴 래버린스 실의 실제 운전조건에 따른 누설량 특성 분석
임샛별(S.B. Lim),김민규(M.K. Kim),강율호(Y.H. Kang),박원규(W.G. Park) 한국전산유체공학회 2015 한국전산유체공학회지 Vol.20 No.4
Recently, There are many studies in progress in order to improve the efficiency of the gas turbine. Leakage in losses of the gas turbine account for the largest proportion. Seal is a sealing device to reduce the flow from leaking by the pressure difference inside the turbine. Compressor has another value according to the shape and pressure conditions in each stage. Thus, it is necessary to seal design for boundary conditions in order to minimize leakage. At the actual operating conditions of the compressor, numerical analysis of honeycomb labyrinth seal was performed in accordance with pressure, temperature, rotor speed for CFD. As a result, when the temperature increases, the leakage is decreased. Also, when the pressure increases linearly with increased leakage, and there was no effect of the rotation speed.