Numerical Analysis of Nonstationary Thermal Response Characteristics for a Fluid-Structure Interaction System

1999 ◽  
Vol 121 (3) ◽  
pp. 276-282 ◽  
Author(s):  
T. Muramatsu
Keyword(s):  
Numerical Method ◽  
Thermal Response ◽  
Temperature Fluctuations ◽  
Scale Model ◽  
Response Analysis ◽  
Simulation Code ◽  
Response Characteristics ◽  
Experimental Approaches ◽  
Damping Effects ◽  
Thermal Striping

Nonstationary thermal response analysis for a fundamental sodium experiment simulating thermal striping phenomena was carried out using a quasi-direct numerical thermohydraulics simulation code with a third-order upwind scheme for convection terms and a boundary element method code for thermal response evaluation of structures due to random sodium temperature fluctuations developed at Power Reactor and Nuclear Fuel Development Corporation (PNC). Discussions centered on an applicability of the numerical method for the damping effects of the temperature fluctuations in the course of heat transfer to the inside of structures from the fully turbulent region of sodium flows through the comparisons with the experiment. From these comparisons, it was confirmed that the numerical method has a sufficiently high potential in accuracy to predict the damping effects of the temperature fluctuations related to the thermal striping phenomena. Consequently, it is concluded that the numerical prediction by the method developed in this study can replace conventional experimental approaches using 1:1 or other scale model aiming at the simulation of the thermal striping phenomena in actual liquid metal fast breeder reactor (LMFBR) plants. Furthermore, economical improvements in the FBR plants can be carried out based on the discussions of optimization and rationalization of the structural design using the numerical methods.

Response Characteristics of Semisubmersible-Type-Megafloat in Waves and Accuracy of Hydroelastic Response Analysis Program VODAC

2002 ◽  
Author(s):  
Hideyuki Suzuki ◽  
Koichiro Yoshida ◽  
Kazuhiro Iijima ◽  
Kentaro Kobayashi
Keyword(s):  
Dynamic Response ◽  
Elastic Response ◽  
Scale Model ◽  
Design Parameters ◽  
Accurate Estimation ◽  
Response Analysis ◽  
Functional Requirements ◽  
Analysis Program ◽  
Floating Structure ◽  
Response Characteristics

Technical feasibility and practical design method of SSMF, a Semi-Submersible-Type-Megafloat, was studied under research funding from Corporation for Advanced Transport and Technology. A SSMF which serves as a airport for local air transportation of isolated islands was assumed in the research. Typical deck size of the SSMF is 2200m long, 300m wide and 9m deep. In the design of the SSMF, column supported type structure was chosen to satisfy the strength and functional requirements in the environmental condition around Japanese islands in the pacific ocean. The deck structure is supported by 320 columns with draft of 16m. In the design of structural dynamics of the SSMF, a computer code VODAC was adopted to calculate hydro-elastic response. VODAC is an analysis program of hydro-elastic response of Very Large Floating Structure (VLFS) which has been developed in University of Tokyo. This paper presents a series of experiments and calculations carried out to investigate response characteristics of SSMF and to confirm capability and accuracy of VODAC. Basin experiments were carried out using a scale model, which is elastically and dynamically similar to the designed SSMF airport, and the response characteristics were clarified. A simple numerical model was also proposed as a simplified model of dynamic response of VLFS. This model is a simple beam on elastic foundation, but it is shown that basic response characteristics of the structure can be relatively accurately expressed by this model. Design parameters were discussed using this model. Relationships between major design parameters and dynamic response characteristics were clarified. Furthermore it was shown that this model is not just a qualitative model but gives relatively accurate estimation of the response. It is shown that this model gives upper limits of response of real structure and a good safe side estimation.

Large Eddy Simulation with Three Kinds of Sub-Grid Scale Model on Temperature Fluctuation of Hot and Cold Fluids Mixing in a Tee

2012 ◽  
Vol 152-154 ◽  
pp. 1307-1312 ◽  
Author(s):  
Tao Lu ◽  
Yong Wei Wang ◽  
Ping Wang
Keyword(s):  
Large Eddy Simulation ◽  
Temperature Fluctuation ◽  
Eddy Viscosity ◽  
Energy Transport ◽  
Flow Model ◽  
Temperature Fluctuations ◽  
Scale Model ◽  
Eddy Simulation ◽  
Large Eddy ◽  
Thermal Striping

In the present work the temperature fluctuations in a mixing tee were simulated on FLUENT platform using the large-eddy simulation (LES) turbulent flow model with three kinds of sub-grid scale (SGS) models such as Smagorinsky-Lilly (SL) model, Wall-adapted Local Eddy-viscosity (WALE) model, and Kinetic-energy transport (KET) model. The normalized mean and root mean square temperatures were predicted and analyzed with consideration of buoyancy. The numerical results showed that buoyancy greatly influences the mixing flow and the thermal striping phenomena were quite obvious. These three SGS models have somewhat similar accuracies for prediction of the temperature fluctuation and thermal stripping in a tee of mixing hot and cold fluids.

scholarly journals Response analysis of random base excitation ona magnetic bearing rotor system

2019 ◽  
Vol 293 ◽  
pp. 04004
Author(s):  
Jinping Chen ◽  
Li Zhang ◽  
Yanyan Luo ◽  
Haining Zhang ◽  
Jun Liu
Keyword(s):  
Collision Detection ◽  
Random Excitation ◽  
Magnetic Bearing ◽  
Rotor System ◽  
Response Analysis ◽  
Random Response ◽  
Practical Application ◽  
External Disturbances ◽  
Response Characteristics ◽  
Auxiliary Bearing

The magnetic bearing-rotor system is subject to various external disturbances in practical application. Under certain control conditions, the random response characteristics of the magnetic bearing-rotor system are a particular concern. This paper analyzes the response characteristics of base of the magnetic bearing subjected to acceleration random excitation in the horizontal direction. First, the magnetic bearing-rotor system model is deduced. Then, the random response of the rotor under acceleration random excitation is derived. The probability of the collision of the rotor between the auxiliary bearing is calculated and the example is given. The paper conclusion provides a theoretical basis for the collision detection and prediction of the magnetic bearing-rotor system.

scholarly journals Seismic Response Analysis and Control of Frame Structures with Soft First Storey under Near-Fault Ground Motions

2020 ◽  
Vol 2020 ◽  
pp. 1-13
Author(s):  
Chunyang Liu ◽  
Peng Sun ◽  
Ruofan Shi
Keyword(s):  
Seismic Response ◽  
Ground Motion ◽  
Seismic Performance ◽  
Frame Structures ◽  
Response Analysis ◽  
Main Structure ◽  
Response Characteristics ◽  
Near Fault ◽  
Buckling Restrained Brace ◽  
Near Fault Ground Motion

This paper proposes two kinds of arrangements of buckling-restrained brace dampers to strengthen soft-first-storey structures locally. Two types of near-fault ground motion, with and without pulse, were selected for a study of the seismic response characteristics of soft-first-storey structures with and without buckling-restrained brace dampers, and the effects of different bracing arrangements on improving the seismic performance of soft-first-storey structures were recognized. The results show that, compared with pulse-free ground motion, near-fault pulsed ground motion results in a more severe seismic response in soft-first-storey frame structures, leading to more serious and rapid destruction of the main structure. Buckling-restrained brace dampers have an obvious energy dissipation effect, play a better role in protecting the main structure, and have good practicality. Compared with structures in which the buckling-restrained brace dampers are arranged only on the bottommost layer, the bottom-four-layer-support structure is more advantageous in terms of seismic performance.

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