• International Journal of Aeronautical and Space Sciences
• /
• 제5권1호
• /
• pp.39-45
• /
• 2004

The vibration characteristics of rotating machinery are directly related withits condition such as rotor types, thereby it should be acquired the information fromthe vibration signal so that operating conditions may be rationally decided.Accordingly, the study is to focus on developing the analysis for identifying theoperational feature of rotor systems. For this purpose the complex frequencyanalysis for identification, which utilizes the directionaI spectrum for effectiveidentification of rotor systems, is introduced. From this proposed method, theanalysis of dynamic model of the rotors is performed including the stabilitybehavior of the general rotor by Ftoquet theory. Through this process theexcitation methodology to identify the types of rotors is investigated and theeffective way to identification is also suggested.

• Journal of Advanced Marine Engineering and Technology
• /
• 제23권2호
• /
• pp.244-251
• /
• 1999

Large dynamic loads act on the rotor in rotary compressors. There are unbalance forces due to eccentric rotation parts and gas forces induced by the pressure difference between compression and suction gases. Rotor-journal bearing system is nonlinear since the stiffness and damping coef-ficients of the lubrication oil film are not constant in the bearings. in this paper the program for predicting the behaviors of rotor-journal bearing system of rotary compressor is developed. Finite element modeling is used to analyze the flexible rotor. The numerical results are compared with experimental results.

• 한국소음진동공학회논문집
• /
• 제27권2호
• /
• pp.204-212
• /
• 2017

The rotor dynamics and balancing technic for rotating equipment during engineering and manufacture stage are to be carefully considered in order to minimize the operation troubles regarding vibration during commissioning stage. In this paper, the test rig, which includes the disks as balancing plane, is designed and manufactured, so that the characteristic of rotor dynamics can be analyzed such as critical speed and mode shape. The critical speed predicted through natural frequency analysis is verified by the actual measurement on bearing housing vibration during start-up condition of test rig. The low speed balancing and the operating speed balancing test are performed respectively with consideration of first critical speed, and the residual unbalance amounts are estimated in accordance with the relevant method described in API standard. In addition, the single and dual plane balancing are carried out on main disk and trim disk depended on phase information at each balancing step.

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2014년도 추계학술대회 논문집
• /
• pp.306-310
• /
• 2014

The purpose of this study is the stability evaluation of a vacuum pump through modal test and rotor dynamics. Eigenvalue was solved by the finite-element method(FEM) using 2D and 3D models, then the modal test result was compared with the FEM result. According to the comparison, the analysis result using the 2D was more accurate than the 3D model. Therefore, rotor dynamics was performed by the 2D model. Campbell diagram and root-locus maps, which were calculated by complex-eigenvalue analysis, were used to evaluate the stability of the rotors of the vacuum pump. And displacement solved by unbalance response analysis was compared with the minimum clearance between two rotors of the vacuum pump. Thus, the vacuum pump is assumed operated under steady state through the evaluation of the rotor dynamics.

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2013년도 추계학술대회 논문집
• /
• pp.103-108
• /
• 2013

This paper describes basic properties tests and non-rotating dynamic test for rotor blade, flexbeam, and torque tube of which bearingless rotor in helicopter consists. A basic properties test are bending and twist test to find the flap stiffness, lag stiffness, and twist stiffness of specimens. The purpose of dynamic test is to find natural frequencies and modes in non-rotating state. The test results are used to update the analysis model. The updated analysis results using rotorcraft comprehensive code match the tests quite well. The updated model input based on the tests will be utilized to analysis the conditions of rotating whirl tower test before the whirl test and will be compared with the whirl tower test results.

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 1997년도 추계학술대회논문집; 한국과학기술회관; 6 Nov. 1997
• /
• pp.50-57
• /
• 1997

A 600HP class high-speed gear driven 3-stage turbo-compressor (IGCC : Integrally Geared Centrifugal Compressor) driven by a 3600 rpm AC induction motor has been designed, of which low speed pinion runs at 35000 rpm and high speed pinion at 50000 rpm nominally. Due to its high speed operation, the system requires very reliable bearing selection and design as well as accurate rotordynamic analysis and prediction of its dynamic behavior to secure the operating reliability. Rotordaynamic analyses of the IGCC rotor-bearing system predicted that the low speed pinion rotor mounted on 5-pad tilting pad bearings has two critical speeds before its design speed and high speed pinion rotor only one critical speed, and estimated critical speeds of both pinion shafts are away from the continuous operating speed enough to satisfy the corresponding API requirement. The forced response analysis with API specified maximum allowable unbalances also showed that unbalance responses are small enough for smooth operation of the system.

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2001년도 추계학술대회논문집 I
• /
• pp.297-303
• /
• 2001

This research presents an analytical model to characterize the ball bearing vibration due to the waviness in a rigid rotor supported by multi-row ball bearings considering centrifugal force and gyroscopic moment of ball. The effects of centrifugal force and gyroscopic moment are introduced to the kinematic constraints and force equilibrium equations. The waviness of ball and races is modeled by the superposition of sinusoidal function and it is introduced to position vectors of race curvature center to use the Hertzian contact theory in order to calculate the elastic deflection and nonlinear contact force resulting from the waviness while the rotor has translational and angular motion. They can be determined by solving the nonlinear equations of motion with five degrees of freedom by using the Runge-Kutta-Fehlberg algorithm. The accuracy of this research is validated by comparing with the results of the prior researches. It characterizes the vibration frequencies resulting from the various kinds of waviness in rolling elements, the harmonic frequencies resulting from the nonlinear load-deflection characteristics of ball bearing resulting from the waviness interaction.

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2004년도 추계학술대회논문집
• /
• pp.242-247
• /
• 2004

In this study was proposed a transient response analysis technique of a rotor system, applying the generalized FE modeling method of a rotor-bearing system considering a base-transferred shock force and together the state-space Newmark method of direct time integration scheme based on the average velocity concept. Experiments were performed to a test rig of a mock-up rotor-bearing system with series of half-sine shock waves imposed by an electromagnetic shaker, and quantitative error analyses between analytical and experimental results were carried out. The transient reponses of the rotor were sensitive to duration times and shape-qualities of the shock waves, and overally the analytical results agreed quite well with the experimental ones. Particularly, in cases that the frequencies, $1/(2{\times}duration\;time)$, of the shock waves were close to the critical speed of the rotor-bearing system, resonances occurred and the transient responses of the rotor were amplified.

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2011년도 추계학술대회 논문집
• /
• pp.264-270
• /
• 2011

The goal of this study is a stability evaluation through eigenvalue and rotor dynamics analysis of the vacuum pump. The vacuum pump used is a roots type pump, one of the dry middle vacuum pumps, is necessary at the procedure to produce semiconductor and display. The eigenvalue evaluation is solved by numerical analysis through using Modal test and 2D 3D models. Both the experiment and the analysis result are similar, the analysis result using 2D is more oculate the 3D model comparing with test result. So rotor dynamic evaluation is performed through using 2D model. Rotor dynamic evaluation used the campbell diagram and root locus map which were acquired by complex eigenvalue analysis. And we checked minimum clearance of vacuum pump composition between two rotors through unbalance response analysis. Thus, vacuum pump, the target object of this study, was evaluated to be operated stably.

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2013년도 춘계학술대회 논문집
• /
• pp.347-352
• /
• 2013

Seoul National University Flap (SNUF) blade is a small-scaled rotor blade incorporating a small trailing-edge flap control surface driven by piezoelectric actuators at higher harmonics for vibration attenuation. Initially, the blade was designed using two-dimensional cross-section analysis and a geometrically exact one-dimensional beam analysis, and material configuration was finalized. Flap deflection angle of ${\pm}45^{\circ}$ was established as the criterion for better vibration reduction performance based on an earlier simulation. Flap linkage mechanism design is carried out and static bench tests are conducted to verify the flap actuation mechanism performance. Different versions of test beds are developed and tested with the flap and chosen APA 200M piezoelectric actuators. Through significant improvements, a maximum deflection of ${\pm}3.7^{\circ}$ was achieved. High frequency experiments are conducted to evaluate the performance and transfer function of the test bed is determined experimentally. As the static tests are almost completed, rotor power required for testing the blade in whirl tower (centrifugal environment) is calculated and further preparations are under way.