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최복성,하태웅 대한기계학회 2014 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.28 No.2
Annular-type gas seals in many types of compressors and turbines are designed to reduce leakage and enhance the vibrational stabilityof the turbo machinery. Many researchers have attempted precise theoretical evaluation of the leakage and the rotordynamic coefficientsfrom reaction forces of small seal gaps. The Bulk-flow model, which is based on Hirs’ lubrication equation, is a general method withadvantages of simplicity and short computing time. However, due to the disadvantage of the long time required to develop analysis code,and constraints from complicated seal shapes, CFD analysis is currently preferred. In the present, the method for determining the rotordynamiccoefficients of an annular plain-gas seal, which is the simplest shape of gas seals, is suggested by extending the analysis of anannular plain-pump seal. A relative coordinate system for steady-state simulation is defined to calculate the compressible flow field anddynamic pressure distribution of the seal gap. The present analysis is verified by comparison with results acquired from Bulk-flow analysiscode and published experimental results. The 3D CFD rotordynamic coefficients results of direct stiffness(K) and cross coupled stiffness(k) show better improvements in prediction.
최복성(BokSung Choi),하태웅(TaeWoong Ha) 한국트라이볼로지학회 2009 한국트라이볼로지학회지 (Tribol. Lubr.) Vol.25 No.2
In order to improve leakage characteristic, angled-circumferential-groove pump seal is suggested. CFD analysis using FLUENT has been performed to predict leakage and determine an optimum slanted-groove angle a which yields the best leakage reduction. The optimum value of a ranges from 45° to 60° and depends on the pressure difference of seal and number of grooves for the same groove geometry. The maximum leakage reduction ratio increases as increasing the pressure difference of angled-circumferential-groove pump seal with the optimum value of a.
최복성(Bok Seong Choe),하태웅(Tae Woong Ha) 한국트라이볼로지학회 2010 한국트라이볼로지학회지 (Tribol. Lubr.) Vol.26 No.1
Precise prediction of rotordynamic coefficients for annular type seal of turbomachinery is necessary for enhancing their vibrational stability and various prediction methods have been developed. As the seal passage is designed complicatedly, the analysis based on Bulk-flow concept which has been mainly used in predicting seal dynamics is limited. In order to improve the seal rotordynamic 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 rotordynamic coefficients of non-contact type annular plain seal using FLUENT. Comparing with the results of Bulk-flow model analysis, the result of 3D CFD analysis shows good agreement.