scholarly journals Study on Vapor Film Collapse Behavior on High Temperature Particle Surface. 1st Report. Measurement of Vapor Film Collapse Pressure.

2000 ◽  
Vol 66 (642) ◽  
pp. 627-632 ◽  
Author(s):  
Yutaka ABE ◽  
Tomoyoshi KOBAYASHI
Keyword(s):  
High Temperature ◽  
Particle Surface ◽  
Vapor Film ◽  
Collapse Pressure ◽  
Collapse Behavior ◽  
Film Collapse

Visual Observation of Vapor Film Collapse Behavior During Vapor Explosion

2002 ◽  
Author(s):  
Yutaka Abe ◽  
Hideki Nariai
Keyword(s):  
High Temperature ◽  
Pressure Pulse ◽  
Film Surface ◽  
Vapor Film ◽  
Visual Data ◽  
Vapor Explosion ◽  
Auto Correlation ◽  
Piv Technique ◽  
Collapse Behavior ◽  
Film Collapse

During severe accident of a light water reactor, various thermal hydraulic phenomena including vapor explosion could threaten the integrity of the containment vessel. Thermal detonation model is proposed to describe the vapor explosion. According to the model, several processes should be sequentially satisfied for the trigger phenomena of the vapor explosion. One of the most important processes for the trigger phenomena is the vapor film collapse around high temperature molten material droplets. In the present study, the vapor film collapse behavior around high temperature solid particle submerged into water was experimentally investigated by attacking a pressure pulse to the vapor film on a high temperature sold particle. The interfacial phenomena between vapor and water were measure by using a high-speed video camera of the maximum speed of 40,500 fps. The visual data obtained were processed with visual data processing techniques. That is, the average vapor film thickness was estimated, dynamic behaviors of the interfaces were analyzed with PIV technique and the interface movement was estimated with the digital auto correlation techniques from the visual data obtained. Furthermore, the transients of the temperature and pressure were simultaneously measured. The interfacial temperatures between vapor and water, and between molted liquid and water are analytically estimated by solving the heat conduction equation with the data obtained as the boundary conditions. It is clarified that vapor collapse by pressure pulse occurs homogeneously around the vapor film surface on a high temperature particle. Microscopic information are obtained from the visual data by using visual data processing technique, PIV technique and digital auto-correlation technique. At the time the vapor film surface changes to white, the saturation temperature exceeds the interfacial temperature. The microscopic vapor film collapse behavior indicates the possibility of the phase change at the vapor film collapse.

scholarly journals 610 Study of Micro-Mechanism of Vapor Film Collapse on the High Temperature Sphere Surface

2000 ◽  
Vol 2000 (0) ◽  
pp. 183-184
Author(s):  
Yutaka ABE ◽  
Hiroshi YANAGIDA ◽  
Hideki NARIAI ◽  
Miki YAGITA
Keyword(s):  
High Temperature ◽  
Vapor Film ◽  
Sphere Surface ◽  
Film Collapse

NUMERICAL SIMULATION OF THE VAPOR FILM COLLAPSE BEHAVIOR AT VAPOR EXPLOSION WITH THREE-DIMENSIONAL LATTICE GAS THERMAL-HYDRAULIC AUTOMATA METHOD

2003 ◽  
Vol 17 (01n02) ◽  
pp. 189-192
Author(s):  
DAISUKE TOCHIO ◽  
YUTAKA ABE ◽  
YOSUKE MATSUKUMA ◽  
HIDEKI NARIAI
Keyword(s):  
Numerical Simulation ◽  
Phase Change ◽  
Lattice Gas ◽  
Three Dimensional ◽  
Experimental Result ◽  
Vapor Film ◽  
Lattice Gas Automata ◽  
Numerical Result ◽  
Collapse Behavior ◽  
Film Collapse

In order to clarify the dominant driving force of complex vapor film collapse behavior, numerical simulation is performed with three-dimensional fifteen-velocity lattice gas automata method. As the result, numerical result is qualitatively different from the experimental result. On the other hand, numerical simulation of vapor film collapse behavior is performed with three-dimensional fifteen-velocity lattice gas automata method including phase-change effect. As the result, numerical result is qualitatively similar to the experimental results. Comparison between the experimental result and the numerical result confirms that experimentally observed vapor film collapse behavior is dominated not by fluid motion but by phase change.

Vapor Film Collapse Behavior during Quenching of Small Platinum Sphere into Polymer Aqueous Solution

2020 ◽  
Vol 2020.69 (0) ◽  
pp. 605
Author(s):  
SHIMAOKA Mitsuyoshi ◽  
YOSHIDA Hiroshi ◽  
IKUTA Fumiaki ◽  
IKEDA Nobuhiro ◽  
NAKAMURA Shigeto
Keyword(s):  
Aqueous Solution ◽  
Vapor Film ◽  
Collapse Behavior ◽  
Film Collapse ◽  
Polymer Aqueous Solution

scholarly journals CFD-DEM Simulation of Spouted Bed Dynamics under High Temperature with an Adhesive Model

Energies ◽  
2021 ◽  
Vol 14 (8) ◽  
pp. 2276
Author(s):  
Zhao Chen ◽  
Lin Jiang ◽  
Mofan Qiu ◽  
Meng Chen ◽  
Rongzheng Liu ◽  
...  
Keyword(s):  
High Temperature ◽  
Particle Surface ◽  
Particle Collision ◽  
Gas Velocity ◽  
Spouted Bed ◽  
Dem Simulation ◽  
Linear Spring ◽  
Adhesion Model ◽  
Adhesive Model ◽  
Damping Model

Particle adhesion is of great importance to coating processes due to its effect on fluidization. Currently, Computational Fluid Dynamics-Discrete Element Method (CFD-DEM) has become a powerful tool for the study of multiphase flows. Various contact force models have also been proposed. However, particle dynamics in high temperature will be changed with particle surface properties changing. In view of this, an adhesion model is developed based on approaching-loading-unloading-detaching idea and particle surface change under high temperature in this paper. Analyses of the adhesion model are given through two particle collision process and validated by experiment. Effects of inlet gas velocity and adhesion intensity on spouted bed dynamics are investigated. It is concluded that fluidization cycle will be accelerated by adhesion, and intensity of fluidization will be marginally enhanced by slight adhesion. Within a certain range, increasing inlet gas velocity will lead to strong intensity of particle motion. A parameter sensitivity comparison of linear spring-damping model and Hertz-Mindlin Model is given, which shows in case of small overlaps, forces calculated by both models have little distinction, diametrically opposed to that of large overlaps.

A Strain Energy-Based Equivalent Layer Method for the Prediction of Critical Collapse Pressure of Flexible Risers

2018 ◽  
Author(s):  
Xiao Li ◽  
Xiaoli Jiang ◽  
Hans Hopman
Keyword(s):  
Strain Energy ◽  
Critical Pressure ◽  
Numerical Models ◽  
Fe Model ◽  
Collapse Pressure ◽  
Layer Method ◽  
Flexible Risers ◽  
Collapse Behavior ◽  
Equivalent Properties ◽  
Equivalent Layer

Flexible risers are one kind of flexible pipes that transport fluid between subsea facilities and topside structures. This pipe-like structure consists of multiple layers and its innermost carcass layer is designed for external hydrostatic pressure resistance. For the flexible risers used in ultra-deep water fields, the critical collapse pressure of the carcass layers is one of the dominant factors in their safety design. However, the complexity of the interlocked carcass design introduces significant difficulties and constraints into the engineering analysis. To facilitate the anti-collapse analysis, equivalent layer methods are demanded to help construct an equivalent pipe that performs a similar collapse behavior of the carcass. This paper proposes a strain energy based equivalent layer method which trying to bridge the equivalence between those two structures by considering equivalent geometric and material properties for the equivalent layer. Those properties are determined through strain energy equivalence and membrane stiffness equivalence. The strain energy of the carcass is obtained through numerical models and is then used in a derived equation set to calculate the equivalent properties for the equivalent layer. After all the equivalent properties have been determined, an equivalent layer FE model is built and used to predict the critical pressure of the carcass. The prediction result is compared to that of the full 3D carcass model as well as the equivalent models that built based on other existing equivalent methods, which shows that the proposed equivalent layer method gives a better performance on predicting the critical pressure of the carcass.

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