• Title/Summary/Keyword: Coupled-Time Integration

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Flow-induced Vibration of Transonic Turbine Cascades Considering Viscosity and Shock Wave Effects (점성 및 충격파효과를 고려한 천음속 터빈 케스케이드의 유체유발 진동해석)

  • Oh, Se-Won;Park, Oung;Kim, Dong-Hyun
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.16 no.9 s.114
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    • pp.937-948
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    • 2006
  • In this study, a fluid/structure coupled analysis system for simulating complex flow-induced vibration (FIV) phenomenon of cascades has been developed. The flow is modeled using Euler and Wavier-Stokes equations with different turbulent models. The fluid domains are modeled using the unstructured grid system with dynamic deformations due to the motion of structural boundary. The Spalart-Allmaras (S-A) and the SST ${\kappa}-{\omega}$ turbulent models are used to predict the transonic turbulent flows. A fully implicit time marching scheme based on the Newmark direct integration method is used in order to solve the coupled governing equations for viscous flow-induced vibration phenomena. For the purpose of validation for the developed FIV analysis system, comparison results for computational analyses of steady and unsteady aerodynamics and flutter analyses are presented in the transonic flow region. In addition, flow-induced vibration analyses for the isolated cascade and multi-blades cascade models have been conducted to show the physical fluid-structure interaction effects in the time domain.

Flow-Induced Vibration of Transonic Turbine Cascades Considering Viscosity and Shock Wave Effects (점성 및 충격파 효과를 고려한 천음속 터빈 케스케이드의 유체유발 진동해석)

  • Oh, Se-Won;Kim, Dong-Hyun;Park, Oung
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2006.05a
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    • pp.793-802
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    • 2006
  • In this study, a fluid/structure coupled analysis system for simulating complex flow-induced vibration (FIV) phenomenon of cascades has been developed. The flow is modeled using Euler and Wavier-Stokes equations with different turbulent models. The fluid domains are modeled using the unstructured grid system with dynamic deformations due to the motion of structural boundary. The Spalart-Allmaras (S-A) and the SST ${\kappa}-{\omega}$ turbulent models are used to predict the transonic turbulent flows. A fully implicit time marching scheme based on the Newmark direct integration method is used in order to solve the coupled governing equations for viscous flow-induced vibration phenomena. For the purpose of validation for the developed FIV analysis system, comparison results for computational analyses of steady and unsteady aerodynamics and flutter analyses are presented in the transonic flow region. In addition, flow-induced vibration analyses for the isolated cascade and multi-blades cascade models have been conducted to show the physical fluid-structure interaction effects in the time domain.

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Flow-induced Vibration Analysis for Cascades with Stator-rotor Interaction and Viscosity Effect (스테이터-로터 상호간섭 및 점성효과를 고려한 케스케이드의 유체유발 진동해석)

  • Oh, Se-Won;Park, Oung;Kim, Dong-Hyun
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.16 no.10 s.115
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    • pp.1082-1089
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    • 2006
  • In this study, advanced computational analysis system has been developed in order to investigate flow-induced vibration(FIV) phenomenon for general stator-rotor cascade configurations. Relative movement of the rotor with respect to stator is reflected by modeling Independent two computational domains. Fluid domains are modeled using the unstructured grid system with dynamic moving and local deforming methods. Unsteady, Reynolds-averaged Wavier-stokes equations with one equation Spalart-Allmaras and two-equation SST ${\kappa}-{\varepsilon}$ turbulence models are solved for unsteady flow problems and also relative moving and vibration effects of the rotor cascade are fully considered. A coupled implicit time marching scheme based on the Newmark integration method is used for computing the governing equations of fluid-structure interaction problems. Detailed vibration responses for different flow conditions are presented and then vibration characteristics are physically investigated in the time domain as computational virtual tests.

Performance Analysis of INS/GPS Integration System (INS/GPS 결합방식에 따른 성능분석)

  • Park, Young-Bum;Lee, Jang-Gyu;Park, Chan-Gook
    • Proceedings of the KIEE Conference
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    • 2000.07d
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    • pp.2433-2435
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    • 2000
  • Inertial Navigation System(INS) provides short-term accurate navigation solution but its error grows with time due to integration characteristics. Meanwhile, Global Positioning System(GPS) provides long-term stable solution but it has poor error characteristics in high dynamic region. So for its synergistic relationship, an integrated INS/GPS systems has been widely used as an advanced navigation system. Generally, two kinds of integration method are used. One is loosely coupled mode which uses GPS-derived position and velocity as measurements in an integrated Kalman filter. The other is tightly coupled one which uses pseudorange and pseudorange rate as Kalman filter measurements. In this paper the system error models and observation models for two kinds of integrated systems are derived, respectively, and their performance are compared through Monte-Carlo simulations.

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An ALE Finite Element Method for Baffled Fuel Container in Yawing Motion

  • Cho, Jin-Rae;Lee, Hong-Woo;Yoo, Wan-Suk;Kim, Min-Jeong
    • Journal of Mechanical Science and Technology
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    • v.18 no.3
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    • pp.460-470
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    • 2004
  • A computational analysis of engineering problems with moving domain or/and boundary according to either Lagrangian or Eulerian approach may encounter inherent numerical difficulties, the extreme mesh distortion in the former and the material boundary indistinctness in the latter. In order to overcome such defects in classical numerical approaches, the ALE(arbitrary Lagrangian Eulerian) method is widely being adopted in which the finite element mesh moves with arbitrary velocity. This paper is concerned with the ALE finite element formulation, aiming at the dynamic response analysis of baffled fuel-storage container in yawing motion, for which the coupled time integration scheme, the remeshing and smoothing algorithm and the mesh velocity determination are addressed. Numerical simulation illustrating theoretical works is also presented.

Time-frequency analysis of a coupled bridge-vehicle system with breathing cracks

  • Wang, W.J.;Lu, Z.R.;Liu, J.K.
    • Interaction and multiscale mechanics
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    • v.5 no.3
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    • pp.169-185
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    • 2012
  • The concrete bridge is likely to produce fatigue cracks during long period of service due to the moving vehicular loads and the degeneration of materials. This paper deals with the time-frequency analysis of a coupled bridge-vehicle system. The bridge is modeled as an Euler beam with breathing cracks. The vehicle is represented by a two-axle vehicle model. The equation of motion of the coupled bridge-vehicle system is established using the finite element method, and the Newmark direct integration method is adopted to calculate the dynamic responses of the system. The effect of breathing cracks on the dynamic responses of the bridge is investigated. The time-frequency characteristics of the responses are analyzed using both the Hilbert-Huang transform and wavelet transform. The results of time-frequency analysis indicate that complicated non-linear and non-stationary features will appear due to the breathing effect of the cracks.

A Study on GPS/INS Integration Considering Low-Grade Sensors (저급 센서를 고려한 GPS/INS 결합기법 연구)

  • Park, Je Doo;Kim, Minwoo;Lee, Je Young;Kim, Hee Sung;Lee, Hyung Keun
    • Journal of Institute of Control, Robotics and Systems
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    • v.19 no.2
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    • pp.140-145
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    • 2013
  • This paper proposes an efficient integration method for GPS (Global Positioning System) and INS (Inertial Navigation System). To obtain accuracy and computational conveniency at the same time with low cost global positioning system receivers and micro mechanical inertial sensors, a new mechanization method and a new filter architecture are proposed. The proposed mechanization method simplifies velocity and attitude computation by eliminating the need to compute complex transport rate related to the locally-level frame which continuously changes due to unpredictable vehicle motions. The proposed filter architecture adopts two heterogeneous filters, i.e. position-domain Hatch filter and velocity-aided Kalman filter. Due to distict characteristics of the two filters and the distribution of computation into the two hetegrogeneous filters, it eliminates the cascaded filter problem of the conventional loosly-coupled integration method and mitigates the computational burden of the conventional tightly-coupled integration method. An experiment result with field-collected measurements verifies the feasibility of the proposed method.

WNS/GPS Integrated System Using Tightly Coupled Method (강결합 기법을 이용한 WNS/GPS 결합 시스템)

  • 조성윤;박찬국
    • Journal of Institute of Control, Robotics and Systems
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    • v.8 no.12
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    • pp.1067-1075
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    • 2002
  • The system error model for the compensation of the low-cost personal navigation system is derived and the error compensation method using GPS is also proposed. The walking navigation system (WNS) that calculates navigation information through walking detection has small error than INS, but the error also increases with time. In order to improve reliability of the system regardless of time, WNS is integrated with GPS. Since WNS is usually used in urban area, the blockage of CPS signal is frequently occurred. Therefore tightly coupled Kalman filter is used for the integration of WNS and GPS. In this paper, the system model for the design of tightly coupled Kかm filter is designed and measurement is linearized in consideration of moving distance error. It is shown by Monte Carlo simulation that the error is bounded even through the number of visible satellite is less than 4.

Planform Curvature Effects on the Stability of Coupled Flow/Structure Vibration (면내 곡률이 천음속 및 초음속 유체/구조 연계 진동 안정성에 미치는 영향)

  • Kim, Jong-Yun;Kim, Dong-Hyun;Lee, In
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.12 no.11
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    • pp.864-872
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    • 2002
  • In this study, the effect of planform curvature on the stability of coupled flow/structure vibration is examined in transonic and supersonic flow regions. The aeroelastic analysis for the frequency and time domain is performed to obtain the flutter solution. The doublet lattice method(DLM) in subsonic flow is used to calculate unsteady aerodynamics in the frequency domain. For all speed range, the time domain nonlinear unsteady transonic small disturbance code has been incorporated into the coupled-time integration aeroelastic analysis (CTIA). Two curved wings with experimental data have been considered in this paper MSC/NASTRAN is used for natural free vibration analyses of wing models. Predicted flutter dynamic pressures and frequencies are compared with experimental data in subsonic and transonic flow regions.

A study on the Integration of Intelligent Robot Workcell using Real Time Communication (실시간 통신을 사용한 Intelligent Robot Workcell의 구성에 관한 연구)

  • Kim, Dong-Jun;Kim, Kab-Il;Jang, Hyuk-Soo;Lee, Byung-Do
    • Proceedings of the KIEE Conference
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    • 1993.07a
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    • pp.406-409
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    • 1993
  • Integration of intelligent robot workcell is now a hot issue in CIM and robotics area. This paper dealt with relatively low level essential topics. i. e., multi-robot coordination and real-time communication for the integration of intelligent robot workcell. For the coordination of multi-robot system, the tightly-coupled coordination is proposed using the various sensors. In order to handle the numerous communication data, time-critical communication network (field-bus) is introduced and investigated. Finally, intelligent robot workcell is suggested using the mini-MAP and field-bus.

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