Rotordynamic Stability and Nonlinear Behavior Characteristics of a Mid-Class High-Speed Turbocharger

An Sung Lee(이안성),Byung Ok Kim(김병옥) 한국소음진동공학회 2010 한국소음진동공학회 학술대회논문집 Vol.2010 No.4

스파이럴 그루브 가스시일의 저ㆍ고속 성능특성 해석

이안성(An Sung Lee),양재훈(Jae-Hun Yang),최동훈(Dong-Hoon Choi) 한국트라이볼로지학회 2004 한국트라이볼로지학회 학술대회 Vol.38 No.-

Applying a general Galerkin FE lubrication analysis method to spiral groove dry gas seals, this study analyzes in detail the effects of groove design parameters, such as a number of groove, spiral angle, groove width ratio, groove radius ratio, groove depth ratio. and groove taper ratio, on the lubrication performances of an opening force, leakage, axial stiffness and damping, and angular stiffness and damping at low and high rotating speeds: 3,600 and 15.000 rpm. Results show that, for the primary design consideration performances such as the opening force and axial and angular stiffnesses, a large number of groove, spiral angle of 25°, groove width ratio of 0.46, groove radius ratio of 1.1, groove depth ratio of 1.0, and groove taper ratio of 0.0 are preferred. Where the recommended relatively low values of groove depth and taper ratios are to keep the axial and angular dampings positive or higher than 0 particularly at the high rotating speed.

깊은 직선 홈 시일의 윤활 성능해석

이안성(An Sung Lee),김준호(Jun Ho Kim) 한국트라이볼로지학회 2003 한국트라이볼로지학회 학술대회 Vol.37 No.-

In this study a general Galerkin FE formulation of the incompressible Reynolds equation is derived for lubrication analyses of noncontacting mechanical face seals. Then, the formulation is applied to analyze the flexibly mounted stator-type reactor coolant pump seals of local nuclear power plants, which have deep straight grooves or plane coning on their primary seal ring faces. Their various lubrication performances have been predicted. Results show that the analyzed deep straight groove seal should have a net coning of less than 0.6 tim to satisfy the leakage limit. And for the same amount of equilibrium opening force the plane coning seal requires to have a 3 times higher dimensionless coning than the deep straight groove seal.

내부 원형 그루브를 갖는 저속 드라이 가스 시일의 윤활 성능해석

이안성(An Sung Lee),김준호(Jun Ho Kim) 한국트라이볼로지학회 2004 한국트라이볼로지학회 학술대회 Vol.39 No.-

In this study a general Galerkin FE lubrication analysis method was utilized to analyze the complex lubrication performance of a spiral groove seal having an additional inner circular groove, which was designed for a chemical process mixer operating at a low speed of the maximum 500 rpm. Equilibrium seal clearance analyses under varying outer pressure revealed that the seal maintains a certain levitation seal clearance under the outer pressure of more than about 1.5 bar, regardless of a rotating speed. Also, under the normal outer pressure of 11 bar, the axial stiffness of the seal was predicted to have a high value of more than 7.0e+07 N/m, regardless of a rotating speed and thereby, the seal is expected to maintain a stable thickness of lubrication film under a certain external excitation acting.

저속 믹서용 드라이 가스 시일의 FE 윤활해석

이안성(An Sung Lee),박무룡(Moo Ryong Park),김영철(Young Cheol Kim) 한국트라이볼로지학회 2003 한국트라이볼로지학회 학술대회 Vol.36 No.-

In this study is presented a general Galerkin-FE gas lubrication analysis method. Then, the method is applied to analyze spiral groove dry gas seals particularly for low-speed mixer applications, where their maximum rotating speeds are 500 rpm. Results show that a spiral groove seal with an additional inner circular groove performs slight better than its counterpart without the inner groove for opening force but only at the expense of more leakage.

25㎿ 산업용 가스터빈의 긴급 손상복구를 위한 베어링 Retrofit 설계 및 시험운전 사례

이안성(An Sung Lee),김병옥(Byung Ok Kim),선경호(Kyung Ho Sun) 한국추진공학회 2014 한국추진공학회 학술대회논문집 Vol.2014 No.12

고속 가스-부상 FE 윤활해석

이안성(An Sung Lee),이동환(Dong Whan Lee),나언주(Uhn Joo Na) 한국트라이볼로지학회 2003 한국트라이볼로지학회 학술대회 Vol.36 No.-

In high-speed gas-levitation applications a high compressibility number often brings a numerical difficulty in predicting generated pressure profiles by causing erroneous sudden pressure overshootings and oscillations in the trailing-edge. To treat the problem, in this study an exact exponential high-order shape function is introduced in the FE lubrication analyses. It is, shown by various examples that the high-order shape function scheme can subdue successfully pressure overshootings and oscillations.

초고속 운전 스파이럴 그루브 드라이 가스 시일의 동특성

이안성(An Sung Lee),김준호(Jun Ho Kimg) 한국트라이볼로지학회 2005 한국트라이볼로지학회 학술대회 Vol.2005 No.6

The dynamic characteristics of a spiral groove dry gas seal, which is being designed for a high-speed flying object application, is investigated. Since at the equilibrium seal clearance its axial stiffness is shown to have almost such a constant high value of 1.04×10? N/m regardless of a rotating speed, the seal is expected to maintain a stable thickness of lubrication film under a certain external excitation. Also, since even at an ultra high-speed of 80,000 rpm its axial damping is shown to have a relatively high value of 5,775 N-s/m, the favorable dynamic stability of the seal at the axial degree of freedom is expected.

LPG액상분사식용 외장형 연료펌프 캐리어의 스파이럴그루브 액체시일의 윤활특성

이안성(An Sung Lee),김창업(Chang Up Kim) 한국자동차공학회 2009 한국자동차공학회 학술대회 및 전시회 Vol.2009 No.11

In this study, to improve fundamentally a poor lubrication durability of critical component carrier at its suction face in a external fuel pump for LPLi fuel system, a spiral groove seal design has been adopted, which can be applied at a low viscosity of liquid LPG. Utilizing the Galerkin finite element lubrication analysis method a lubrication characteristic analysis of the seal has been carried out in detail, and its lubrication performance optimization has been performed by systematic parameter study. Compared to a reference design, a final optimized spiral groove seal design has shown the result of increasing a groove depth by 66.7% to 2.5 ㎛ while increasing an equilibrium seal clearance by 65.3%. It has been predicted from the analysis that at the equilibrium condition between the closing force of pumping pressure and the seal opening force, the optimally designed carrier spiral groove liquid seal is capable of maintaining a stable lubricating film with an axial stiffness coefficient of 3.376×10? N/M and operating in noncontact and in addition leakage through the seal is very minimal.t here. Put Abstract here. Put Abstract here. Put Abstract here. Put Abstract here. Put Abstract here. Put Abstract here.

프로세스 고속 경량 원심 압축기의 로터다이나믹 안정성 강화를 위한 설계해석

이안성(An Sung Lee) 한국트라이볼로지학회 2014 한국트라이볼로지학회지 (Tribol. Lubr.) Vol.30 No.1

In this Part II study, rotordynamic stability analyses were carried out to confirm improvements to the stability of a process high-speed lightweight centrifugal compressor, depending on the effects of tilting pad journal bearing designs. The bearing design variables considered were the clearances, LBPs, LOPs, and preloads. The results showed that the rotordynamic stability of the subject compressor rotor-bearing system improves exactly in accordance with the effects of the bearing design variables, which were determined in the preceding Part I study, owing to reduced bearing stiffnesses. Specifically, it was confirmed that the stability of the rotor system can be greatly improved by increasing both the machined and assembled bearing clearances, but there were no stability improvements by simply changing from an LBP to an LOP design. In addition, it was confirmed that for given fixed machined bearing clearances, the stability can be additionally improved by decreasing the preloads, i.e., by increasing the assembled clearances. In conclusion, it may be necessary to improve the designs of the original tilting pad bearings to obtain a sufficient margin of rotordynamic stability against a possible aerodynamic cross-coupled stiffness in a process high-speed centrifugal compressor. Thus, increasing the machined and assembled bearing clearances and decreasing the preload could be effective solutions.