scholarly journals Explanation of Turbulence Mixing Mechanism at Downstream Region of T-junction Piping Systems (I) : Generation Possibility of Lower Frequency Components and the Confirmation by Fundamental Experiments

2002 ◽  
Vol 2002.15 (0) ◽  
pp. 557-558
Author(s):  
Toshiharu MURAMATSU ◽  
Satoshi MURAKAMI
Keyword(s):  
Downstream Region ◽  
Piping Systems ◽  
Turbulence Mixing ◽  
Frequency Components

Numerical Investigations of Arched Vortex Characteristics Generated at T-Junction Piping Systems

2004 ◽  
Author(s):  
Toshiharu Muramatsu
Keyword(s):  
Stokes Equations ◽  
Velocity Ratio ◽  
Navier Stokes ◽  
Fluid Temperature ◽  
Simulation Code ◽  
Navier Stokes Equations ◽  
Downstream Region ◽  
Piping Systems ◽  
Frequency Components ◽  
Thermal Striping

Thermohydraulic analyses for a fundamental water experiment simulating thermal striping phenomena at T-junction piping systems were carried out using a quasi-direct numerical simulation code DINUS-3, which is represented by instantaneous Navier-Stokes equations and deals with a modified third-order upwind scheme for convection terms. Calculated results were compared with experimental results on the flow patterns in the downstream region of the systems, the arched vortex structures under a deflecting jet condition, the generation frequency of the arched vortex, etc. in the various conditions; i.e., diameter ratio α, flow velocity ratio β and Reynolds number Re. From the comparisons, it was confirmed that (1) the DINUS-3 code is applicable to the flow pattern classifications in the downstream region of the T-junction piping systems, (2) the arched vortex characteristics with lower frequency components and their generation possibilities can be estimated numerically by the DINUS-3 code, and (3) special attentions should be paid to the arched vortex generations with lower frequency components of fluid temperature fluctuations in the design of T-junction systems from the viewpoints of the avoidances for the thermal striping.

Numerical Investigations of a Turbulence Mixing Process Related to Thermal Striping Phenomena at a T-Junction of Liquid Metal Fast Reactor Piping Systems

2002 ◽  
Author(s):  
Toshiharu Muramatsu
Keyword(s):  
Liquid Metal ◽  
Fast Reactor ◽  
Evaluation System ◽  
Velocity Ratio ◽  
Piping System ◽  
Mixing Process ◽  
Downstream Region ◽  
Piping Systems ◽  
Turbulence Mixing ◽  
Thermal Striping

Fluid-structure thermal interaction phenomena characterized by stationary random temperature fluctuations, namely thermal striping are observed in the downstream region of a T-junction piping system of liquid metal fast reactor (LMFR). Therefore the piping walls located in the downstream region must be protected against the stationary random thermal process which might induced high-cycle fatigue. This paper describes the evaluation system based on numerical simulation methods for the thermal striping, and numerical results of the thermal striping at a T-junction piping system under the various parameters, i.e., velocity ratio and diameter ratio between both the pipes and Reynolds number. Then detailed turbulence mixing process at the T-junction piping region due to arched vortexes generating lower frequency fluctuations are evaluated through a separate numerical analysis of a fundamental water experiment.

Numerical Simualtion of Turbulence Mixing Characteristic in Various Secondary Flow Conditions at T-Junction Piping Systems

2004 ◽  
Author(s):  
Masa-aki Tanaka ◽  
Toshiharu Muramatsu
Keyword(s):  
Numerical Simulation ◽  
Secondary Flow ◽  
Temperature Fluctuation ◽  
Safety Issue ◽  
Flow Direction ◽  
Branch Pipe ◽  
Flow Conditions ◽  
Simulation Code ◽  
Piping Systems ◽  
Turbulence Mixing

Temperature fluctuation caused by mixing the fluids with different temperature in a T-junction pipe gives eventually thermal fatigue to structure, and this phenomenon is significant as safety issue in liquid metal cooled fast reactor (LMFBR). In Japan Nuclear Cycle Development Institute (JNC), experimental and numerical investigations have been performed to clarify the mixing phenomena in the T-junction pipe and to establish an evaluation rule for design. If the T-junction pipe is set near an elbow pipe, turbulence mixing is surly affected by the secondary flow generated in the elbow pipe and it is necessary to study the influence of the secondary flow on the temperature fluctuation in the T-junction pipe. We carried out investigation into the secondary flow effect by numerical simulation using a quasi-direct numerical simulation code. Numerical simulation is conducted on the existing experiment, in which the test section simulated the T-junction pipe with the elbow pipe in LMFBR. Major parameter in the numerical simulation is the flow direction of the branch pipe to the flow direction of the elbow pipe. We discuss the influences of the secondary flow on turbulent mixing behavior, and also clarify the mixing mechanism in T-junction pipe.

K-1340 Study on Turbulence Mixing Characteristics at T-Junction Piping Systems : Numerical Evaluations of Arched Vortexes

2001 ◽  
Vol II.01.1 (0) ◽  
pp. 193-194
Author(s):  
Satoshi MURAKAMI ◽  
Toshiharu MURAMATSU ◽  
Kozo SUDO ◽  
Hideki HIBARA
Keyword(s):  
Mixing Characteristics ◽  
Piping Systems ◽  
Turbulence Mixing

Application of Optimal Design Methodology on the Seismic Design of Piping Systems Supported by Elasto-Plastic Dampers

2006 ◽  
Author(s):  
Tomohiro Ito ◽  
Masashi Michiue ◽  
Katsuhisa Fujita
Keyword(s):  
Genetic Algorithm ◽  
Seismic Design ◽  
Design Methodology ◽  
Structural Integrity ◽  
Optimal Conditions ◽  
Evaluation Functions ◽  
Piping Systems ◽  
Frequency Components ◽  
Lead Melt ◽  
Energy Absorbing

In this study, the optimal seismic design methodology which can consider the structural integrity of both the piping systems and the elasto-plastic supporting devices are developed. This methodology employs genetic algorithm and can search the optimal conditions such as the supporting location, the capacity and stiffness of the supporting devices. The lead extrusion damper is treated here as a typical elasto-plastic damper. Four kinds of evaluation functions; stress of piping systems, energy absorption, lead melt of dampers and energy absorbing balance are considered and each optimal condition is clarified and discussed. As the results, it is found that the optimal seismic design methodology proposed here is very effective and can be applied to the actual seismic designs for the piping systems supported by the elasto-plastic dampers, and can be also applied to the piping systems exposed to the actual earthquake waves which have various frequency components and the piping systems with a heavy local mass.

Simulations of high-resolution images of amorphous silicon films

1986 ◽  
Vol 44 ◽  
pp. 544-545
Author(s):  
G. Y. Fan ◽  
J. M. Cowley
Keyword(s):  
Electron Microscope ◽  
High Frequency ◽  
Fourier Transformation ◽  
Amorphous Materials ◽  
Low Frequency ◽  
Chromatic Aberration ◽  
Structure Information ◽  
Frequency Components ◽  
High Resolution Images ◽  
Spatial Frequency Spectrum

It is well known that the structure information on the specimen is not always faithfully transferred through the electron microscope. Firstly, the spatial frequency spectrum is modulated by the transfer function (TF) at the focal plane. Secondly, the spectrum suffers high frequency cut-off by the aperture (or effectively damping terms such as chromatic aberration). While these do not have essential effect on imaging crystal periodicity as long as the low order Bragg spots are inside the aperture, although the contrast may be reversed, they may change the appearance of images of amorphous materials completely. Because the spectrum of amorphous materials is continuous, modulation of it emphasizes some components while weakening others. Especially the cut-off of high frequency components, which contribute to amorphous image just as strongly as low frequency components can have a fundamental effect. This can be illustrated through computer simulation. Imaging of a whitenoise object with an electron microscope without TF limitation gives Fig. 1a, which is obtained by Fourier transformation of a constant amplitude combined with random phases generated by computer.

Facial Image Super-Resolution Reconstruction Based on Separated Frequency Components

2013 ◽  
Vol E96.A (6) ◽  
pp. 1315-1322 ◽  
Author(s):  
Hyunduk KIM ◽  
Sang-Heon LEE ◽  
Myoung-Kyu SOHN ◽  
Dong-Ju KIM ◽  
Byungmin KIM
Keyword(s):  
Super Resolution ◽  
Facial Image ◽  
Frequency Components ◽  
Image Super Resolution

ANALYSIS OF STAND RESEARCH RESULTS OF AXIAL DYNAMIC FORCE IN DRILLING BY THREE ROLLER CONE BIT

2019 ◽  
pp. 81-93
Author(s):  
В. М. Мойсишин ◽  
M. V. Lyskanych ◽  
R. A. Zhovniruk ◽  
Ye. P. Majkovych
Keyword(s):  
Low Frequency ◽  
Maximum Energy ◽  
Dynamic Force ◽  
Low Frequency Oscillation ◽  
Drilling Tool ◽  
Rock Destruction ◽  
Frequency Components ◽  
Harmonic Components ◽  
Experimental Values ◽  
Harmful Effects

The purpose of the proposed article is to establish the causes of oscillations of drilling tool and the basic laws of the distribution of the total energy of the process of changing the axial dynamic force over frequencies of spectrum. Variable factors during experiments on the classical plan were the rigidity of drilling tool and the hardness of the rock. According to the results of research, the main power of the process of change of axial dynamic force during drilling of three roller cone bits is in the frequency range 0-32 Hz in which three harmonic frequency components are allocated which correspond to the theoretical values of low-frequency and gear oscillations of the chisel and proper oscillations of the bit. The experimental values of frequencies of harmonic components of energy and normalized spectrum as well as the magnitude of the dispersion of the axial dynamic force and its normalized values at these frequencies are presented. It has been found that with decreasing rigidity of the drilling tool maximum energy of axial dynamic force moves from the low-frequency oscillation region to the tooth oscillation area, intensifying the process of rock destruction and, at the same time, protecting the tool from the harmful effects of the vibrations of the bit. Reducing the rigidity of the drilling tool protects the bit from the harmful effects of the vibrations generated by the stand. The energy reductions in these fluctuations range from 47 to 77%.

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