• 소음진동
• /
• 제9권3호
• /
• pp.554-564
• /
• 1999

This paper presents the analytical method to evaluate the seismic responses on steam turbine-generator rotor system. Deterministic analytical methods, such as response spectrum approach, modal superposition method and direct integration method, are used to calculate the seismic response. The computer software is also developed based on the methods then can be applied to estimate the seismic safety of turbine-generator rotor system for power plants. Numerical example of a steam turbine-generator rotor system of 1007MW nuclear power plant is presented. The aseismatic performance are checked by comparing maximum seismic deflection at bearing positions with bearing clearance.

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2001년도 추계학술대회논문집 II
• /
• pp.1026-1031
• /
• 2001

In this paper. the dynamic characteristics of a super high-speed tilting-pad air bearing(TPGB) used in a turbo expander with high expansion ratio are analyzed. The dynamic behavior and stability of a rotary system supported by two journal air bearings are investigated numerically. The transient response of the shaft is obtained by simultaneously solving the equation of motion of the shaft and the dynamic Reynolds equation. The stiffness and damping coefficients of the bearing are calculated from the loading coefficients of the bearing are calculated from the loading capacity. shaft velocity and displacement by using a curve fitting method. The natural frequencies of the 1st and 2nd rigid modes can be calculated from these coefficients. The theoretical method of a rigid rotor system is verified by experimentsut.

• 폴리머
• /
• 제37권2호
• /
• pp.204-210
• /
• 2013

첨가제(윤활제 및 산화방지제)와 용융혼합 조건(온도, 시간 및 로터 속도)이 폴리프로필렌(PP) 기반 WPC(wood polymer composite)의 기계적 특성에 미치는 영향을 조사하였다. WPC는 용융혼합 후 압축성형하여 제조하였다. 용융혼합 과정을 이해하기 위해 WPC 용융혼합물의 토크 변화를 측정하였다. 말레산무수물로 개질된 폴리프로필렌을 상용화제로, 나노점토를 보강재로 각각 사용하였다. WPC의 기계적 특성을 측정하기 위해 UTM과 충격시험기를 이용하였고 색차계를 이용하여 WPC의 용융혼합 조건에 따른 변색을 측정하였다. 기계적 특성 분석에 따른 최적용융혼합 조건은 $170^{\circ}C$, 15분, 60 rpm인 것으로 나타났다. 윤활제와 산화방지제의 함량이 증가할수록 WPC의 기계적 특성이 하락함을 확인하였다. 용융혼합 과정에서 목분만을 별도로 나중에 투입하는 이단계 방법이 전형적인 일단계 방법보다 WPC의 기계적 특성 향상에 더 효과적이었다.

• 한국정밀공학회지
• /
• 제23권3호
• /
• pp.139-146
• /
• 2006

The spindle system with a built-in motor can be used to simplify the structure of machine tools, to improve the machining flexibility of machine tools, and to perform the high speed machining. For more quantitative analysis of a built-in motor's dynamic characteristics, that of tile mass and stillness effects are considered. And the drawbar in the spindle can be in various condition according to supporting stiffness between drawbar and shaft. Therefore, in this paper following items are performed and analyzed : 1. Modal characteristics of the spindle. 2. Analysis of rotor's mass and stiffness effects. 3. Modal characteristics of the spindle including drawbar, rotor and tool. The results show enough stiff supports must be provided between shaft and drawbar to prevent occurring drawbar vibration lower than the natural frequency of 1st bending mode of the spindle, and considering the mass and stiffness of built-in motor's rotor is important thing to derive more accurate results.

• 한국항공우주학회지
• /
• 제39권12호
• /
• pp.1097-1106
• /
• 2011

제자리 비행하는 헬리콥터 전기체 형상으로부터 발사되는 유도무기 운동을 모사하기 위해 비정렬 중첩격자기법을 6자유도 운동 기법과 연계하여 비정상 해석을 수행하였다. 주로 터, 꼬리로터, 그리고 유도무기를 포함하는 동체로 구성되는 헬리콥터 전기체 형상에 대한 비정상 해석을 수행하였으며, 6자유도 운동 기법을 이용하여 헬리콥터에서 발사되는 유도 무기의 초기 발사 거동을 예측하였다. 발사위치 및 유도무기의 추력크기에 따른 발사거동을 비교하였으며, 주로터에서 발생하는 비정상 내리흐름에 따른 유도무기의 비행 특성을 분석하였다.

• 항공우주기술
• /
• 제3권2호
• /
• pp.248-255
• /
• 2004

본 논문에서는 반응면 기법(response surface method)과 2차원 Navier-Stokes 방정식 해법을 이용하여 에어포일을 설계하였다. 수치 실험점들은 D-optimal 방법을 기반으로 선정하였으며 반응면 함수는 JMP를 이용하여 2차의 함수로 구성하였다. 설계기법의 검증은 NACA 64621 에어포일을 기저로 하여 Bell 에어포일의 공력특성을 갖도록 역설계하여 수행하였다. 설계기법은 스마트 무인기의 장기체공 능력을 위한 에어포일과 무인기용 로터에 적합한 저 Reynolds 에어포일 설계에 적용하였으며 제약조건을 만족하는 우수한 공력특성의 에어포일을 획득할 수 있었다.

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2001년도 춘계학술대회논문집
• /
• pp.521-527
• /
• 2001

The dynamic performance analyses and tests for a 50kW turbo-generator (KIMM-TG50) were carried out. The operating concept of this machine is that it gets the initial driving force from the built-in motor-generator until it reaches its self-sustaining speed of 40,000 rpm, and then the driving mode is changed to self-operating mode by the combustor installed between the centrifugal compressor and the turbine. Due to winding mistake of motor-generator, the system could go only up to 22000 rpm by the motor so that high pressure air externally fed into the turbine was utilized to get the system to run up to 62,000 rpm thereafter. The vibration data collected during the tests revealed that the first bending critical speed is in near 5,600 rpm as predicted in the design stage of the rotor-bearing system, and that there were no other identifiable critical speeds up until 62,000 rpm due to high damping from the squeeze film damper-bearings supporting the rotor. This paper presented some of the experimental results along with dynamic performance predictions made in the design stage as a part of progress being made.

• 한국전산유체공학회:학술대회논문집
• /
• 한국전산유체공학회 2011년 춘계학술대회논문집
• /
• pp.236-239
• /
• 2011

This paper introduces the design concepts and characteristics of WinDS3000$^{TM}$(TC IIa) which is a trade name of Doosan's 3MW offshore/onshore wind turbine. WinDS3000$^{TM}$(TC IIa) has been designed in consideration of high Reliability, Availability, Maintainability and Serviceability (RAMS) and low cost of electricity (CDE) for the TC IIa condition based on GL guideline. An integrated drive-train design with an innovative three-stage gearbox has been introduced to minimize nacelle weight of the wind turbine and to enhance a high reliability for transmission. A permanent magnet generator with full converter system has been introduced to get higher efficiency in partial load operation and grid-friendly system for both 50 Hz and 60 Hz. A pitch-regulated variable speed control system has been introduced to control wind turbine power while generator reaction torque can be adjusted almost instantaneously by the associated power electronics. The wind turbine has been also equipped with condition monitoring and diagnostic systems in order to meet maintainability requirements.

• 동력기계공학회지
• /
• 제7권3호
• /
• pp.48-53
• /
• 2003

This paper deals with the control of a horizontally placed flexible rotor levitated by electromagnets in a multi-input/multi-output (MIMO) active magnetic bearing(AMB) system. AMB is a kind of novel high performance bearing which can suspend the rotor by magnetic force. Its contact-free manner between the rotor and stator results in it being able to operate under much higher speed than conventional rolling bearings with relatively low power losses, as well as being environmental-friendly technology for AMB system having no wear and no lubrication requirements. In this MIMO AMB system, the rotor is a complex mechanical system, it not only has rigid body characteristics such as translational and slope motion but also bends as a flexible body. Reduced order nominal model is computed by consideration of the first 3 mode shapes of rotor dynamics. Then, the $H_{\infty}$ control strategy is applied to get robust controller. Such robustness of the control system as the ability of disturbance rejection and modeling error is guaranteed by using $H_{\infty}$ control strategy. Simulation results show the validation of the designed control system and the modeling method to the rotor.

• 한국정밀공학회지
• /
• 제18권2호
• /
• pp.119-125
• /
• 2001

This paper presents an experimental study on active control of self-excited vibration for a high speed turbomachinery. In order to suppress the self-excited vibration, it is necessary to actively control the air film pressure or the air film thickness. In this study, active pads are used to control the air film thickness. Active pads are supported by pivots containing piezoelectric actuators and their radial position can be actively controlled by applying voltage to the actuators. The transfer characteristics from actuator inputs to shaft vibration outputs are experimentally investigated. In a tilting-pad gas bearing (TPGB), a shaft is supported by the pressurized air film. Four gap sensors were used to measure the vibration of the shaft and PID was used in the feedback control of the shaft vibration. The experimental results show that the self-excited vibration of the rotor can be effectively suppressed if the PID controller gains are properly chosen. As a result we find that the feedback control is effective for suppressing the self-excited vibration of a rotor system using stack-type PZT actuators.