Numerical Simulation of Thermal Behavior of a Molten Droplet Covered With Vapor Film

2014 ◽  
Author(s):  
Mingjun Zhong ◽  
Meng Lin ◽  
Jinbiao Xiong ◽  
Yankai Li ◽  
Yanhua Yang
Keyword(s):  
Experimental Studies ◽  
Vapor Film ◽  
Volume Of Fluid Method ◽  
Molten Droplet ◽  
Material Density ◽  
Phase Code ◽  
Liquid Systems ◽  
Droplet Behavior ◽  
Simulation Results ◽  
Multi Phase

When the molten fuel with high temperature falls into the cavity water, it will be dispersed to droplets which are covered with vapor films due to the rapid heat transfer with phase transition. This situation cannot be simply described by liquid-liquid nor gas-liquid systems. And there are not sufficient experimental studies on the behavior of droplet covered with vapor film because of the rapid reaction and the difficulty in capture of the film configuration. In this paper, A multi-phase code with the Volume of Fluid Method (VOF) is developed to simulate the behavior of droplet covered with vapor film. Thermal effect is considered. The simulation results indicate that the film thickness and material density have significant effect on the behavior of droplet. The situation assumed in Ciccarelli and Frost’s model is observed in current simulation of thermal droplet behavior.

scholarly journals A Numerical Analysis Research on Earlier Behavior of Molten Droplet Covered with Vapor Film at the Stage of Triggering and Propagation in Steam Explosion

2014 ◽  
Vol 2014 ◽  
pp. 1-10 ◽  
Author(s):  
Mingjun Zhong ◽  
Yankai Li ◽  
Meng Lin ◽  
Minghao Yuan ◽  
Yanhua Yang
Keyword(s):  
Pressure Pulse ◽  
Experimental Studies ◽  
Hydrodynamic Effect ◽  
Vapor Film ◽  
Droplet Deformation ◽  
Molten Droplet ◽  
Material Density ◽  
Liquid Systems ◽  
Droplet Behavior ◽  
Very High

When the molten fuel with high temperature falls into the cavity water, it will be dispersed into droplets which are covered with vapor films due to the rapid heat transfer with phase transition. This situation cannot be simply described by liquid-liquid or gas-liquid systems. And there are no sufficient experimental studies on the behavior of droplet covered with vapor film because of the rapid reaction and the difficulty in capture of the film configuration. In this paper, a multiphase code with the volume of fluid (VOF) method is used to simulate the earlier behavior of droplet when vapor film exits. The earlier behavior is defined as behavior of the droplet before its disintegration. Thermal effect and pure hydrodynamic effect are, respectively, considered. The simulation results indicate that the film thickness and material density have significant effect on the earlier behavior of droplet. The situation assumed in Ciccarelli and Frost’s model (1994) is observed in current simulation of earlier thermal droplet behavior. The effect of triggering pressure pulse on earlier hydrodynamic behavior is also discussed and it indicates that vapor film has little effect on the hydrodynamic droplet deformation when the intensity of the pressure pulse is very high.

scholarly journals Optimizing Transmit Sequence and Instrumental Variables Receiver for Dual-Function Complexity System

Complexity ◽  
2020 ◽  
Vol 2020 ◽  
pp. 1-13
Author(s):  
Yu Yao ◽  
Junhui Zhao ◽  
Lenan Wu
Keyword(s):  
Approximate Solution ◽  
Instrumental Variables ◽  
Performance Index ◽  
Dual Function ◽  
Np Hard ◽  
Match Filter ◽  
Filter Output ◽  
Phase Code ◽  
Discrete Phase ◽  
Simulation Results

This correspondence deals with the joint cognitive design of transmit coded sequences and instrumental variables (IV) receive filter to enhance the performance of a dual-function radar-communication (DFRC) system in the presence of clutter disturbance. The IV receiver can reject clutter more efficiently than the match filter. The signal-to-clutter-and-noise ratio (SCNR) of the IV filter output is viewed as the performance index of the complexity system. We focus on phase only sequences, sharing both a continuous and a discrete phase code and develop optimization algorithms to achieve reasonable pairs of transmit coded sequences and IV receiver that fine approximate the behavior of the optimum SCNR. All iterations involve the solution of NP-hard quadratic fractional problems. The relaxation plus randomization technique is used to find an approximate solution. The complexity, corresponding to the operation of the proposed algorithms, depends on the number of acceptable iterations along with on and the complexity involved in all iterations. Simulation results are offered to evaluate the performance generated by the proposed scheme.

An analytical model for predicting the shear strength of unsaturated soils

2022 ◽  
pp. 1-57
Author(s):  
Tuan A. Pham ◽  
Melis Sutman
Keyword(s):  
Shear Strength ◽  
Analytical Model ◽  
Unsaturated Soils ◽  
High Performance ◽  
Micromechanical Model ◽  
Experimental Studies ◽  
Stress Equilibrium ◽  
Proposed Model ◽  
New Equation ◽  
Multi Phase

The prediction of shear strength for unsaturated soils remains to be a significant challenge due to their complex multi-phase nature. In this paper, a review of prior experimental studies is firstly carried out to present important pieces of evidence, limitations, and some design considerations. Next, an overview of the existing shear strength equations is summarized with a brief discussion. Then, a micromechanical model with stress equilibrium conditions and multi-phase interaction considerations is presented to provide a new equation for predicting the shear strength of unsaturated soils. The validity of the proposed model is examined for several published shear strength data of different soil types. It is observed that the shear strength predicted by the analytical model is in good agreement with the experimental data, and get high performance compared to the existing models. The evaluation of the outcomes with two criteria, using average relative error and the normalized sum of squared error, proved the effectiveness and validity of the proposed equation. Using the proposed equation, the nonlinear relationship between shear strength, saturation degree, volumetric water content, and matric suction are observed.

Application of Hybrid Biosystems for Stimulation of Oil Production

2021 ◽  
Author(s):  
Baghir Alakbar Suleimanov ◽  
Sabina Jahangir Rzayeva ◽  
Ulviyya Tahir Akhmedova
Keyword(s):  
Oil Recovery ◽  
Single Phase ◽  
Experimental Studies ◽  
Oil Production ◽  
Pore Channel ◽  
Subcritical Region ◽  
Slippage Effect ◽  
Liquid Systems ◽  
Reservoir Conditions

Abstract Microbial enhanced oil recovery is considered to be one of the most promising methods of stimulating formation, contributing to a higher level of oil production from long-term fields. The injection of bioreagents into a reservoir results in the creation of oil-dicing agents along with significant amount of gases, mainly carbon dioxide. In early, the authors failed to study the preparation of self-gasified biosystems and the implementation of the subcritical region (SR) under reservoir conditions. Gasified systems in the subcritical phase have better oil-displacing properties than non-gasified systems. The slippage effect determines the behavior of gas–liquid systems in the SR under reservoir conditions. Slippage occurs more easily when the pore channel has a smaller average radius. Therefore, in a heterogeneous porous medium, the filtration profile of gasified liquids in the SR should be more uniform than for a degassed liquid. The theoretical and practical foundations for the preparation of single-phase self-gasified biosystems and the implementation of the SR under reservoir conditions have been developedSR under reservoir conditions. Based on experimental studies, the superior efficiency of oil displacement by gasified biosystems compared with degassed ones has been demonstrated. The possibility of efficient use of gasified hybrid biopolymer systems has been shown.

Numerical Simulation of Oil Mist Process in Cold Heading Machine

2010 ◽  
Vol 37-38 ◽  
pp. 739-742
Author(s):  
Gao Chun Xu ◽  
Qing Xi Hu ◽  
Li Min Li ◽  
Chun Xiang Dai
Keyword(s):  
Fluid Dynamics ◽  
Green Manufacturing ◽  
Stream Line ◽  
Mist Flow ◽  
Multi Phase Flow ◽  
Oil Mist ◽  
Simulation Results ◽  
Line Path ◽  
Multi Phase ◽  
Inlet Position

Based on control equations in fluid dynamics, the main thought of oil mist process for cold heading machine is proposed according to the idea of green manufacturing. The computation fluid dynamics (CFD) software is applied to simulate the multi-phase oil mist flow in control box. The simulation results give some figures including distribution and stream line path of multi-phase flow of oil mist in the control box. The results show that the inlet position of oil mist effects on its process and three types of control box are compared, from which the best type is obtained.

scholarly journals Computational Approaches for Studying Slag–Matte Interactions in the Flash Smelting Furnace (FSF) Settler

Processes ◽  
2020 ◽  
Vol 8 (4) ◽  
pp. 485
Author(s):  
Jani-Petteri Jylhä ◽  
Nadir Ali Khan ◽  
Ari Jokilaakso
Keyword(s):  
Flash Smelting ◽  
Copper Production ◽  
Limiting Factor ◽  
Molten Droplet ◽  
Geometry Modeling ◽  
Droplet Behavior ◽  
Flow Phenomena ◽  
Modeling Software ◽  
Flash Smelting Furnace ◽  
Physical Phenomena

Computational methods have become reliable tools in many disciplines for research and industrial design. There are, however, an ever-increasing number of details waiting to be included in the models and software, including, e.g., chemical reactions and many physical phenomena, such as particle and droplet behavior and their interactions. The dominant method for copper production, flash smelting, has been extensively investigated, but the settler part of the furnace containing molten high temperature melts termed slag and matte, still lacks a computational modeling tool. In this paper, two commercial modeling software programs have been used for simulating slag–matte interactions in the settler, the target being first to develop a robust computational fluid dynamics (CFD) model and, second, to apply a new approach for molten droplet behavior in a continuum. The latter is based on CFD coupled with the discrete element method (DEM), which was originally developed for modeling solid particle–particle interactions and movement, and is applied here for individual droplets for the first time. The results suggest distinct settling flow phenomena and the significance of droplet coalescence for settling velocity and efficiency. The computing capacity requirement for both approaches is the main limiting factor preventing full-scale geometry modeling with detailed droplet interactions.

Gas-Newtonian and Gas-Non-Newtonian Slug Flow in Vertical Pipe, Part I: Gas Holdup Characteristics

2010 ◽  
Vol 8 (1) ◽  
Author(s):  
Subrata Kumar Majumder ◽  
Sandip Ghosh ◽  
Arun Kumar Mitra ◽  
Gautam Kundu
Keyword(s):  
Slug Flow ◽  
Oil And Gas ◽  
Experimental Studies ◽  
Industrial Applications ◽  
Transportation Systems ◽  
Gas Holdup ◽  
Newtonian Liquid ◽  
Biochemical Engineering ◽  
Two Phase ◽  
Liquid Systems

Studies on two-phase gas-liquid co-current flow with non-Newtonian liquid system has attracted the attention of researchers over the years due to its wide-spread applications and importance in various different processes in chemical and biochemical industries, such as the process of two-phase in oil and gas wells, transportation systems of crude and refined products, and food processing in biochemical engineering and bio-reactors. This article examines the sole objective of experimental studies on gas holdup in Newtonian and non-Newtonian liquid slug flow within a range of gas and liquid flowrate of 0.5×10-4 to 1.92×10-4 m3/s and 1.6×10-4 to 6.7×10-4 m3/s, respectively. The present data was analyzed with different models. To predict gas holdup, correlations have been developed for individual system with Newtonian and non-Newtonian liquid. A general correlation was also developed to predict the gas holdup combing both the Newtonian and non-Newtonian liquid systems. The study of the gas holdup characteristics in gas-Newtonian and non-Newtonian liquid systems may give insight into a further understanding and modeling of this slug flow characteristics in industrial applications.

Friction-Induced Vibration in Lead Screw Systems: Mathematical Modeling and Experimental Studies

2009 ◽  
Vol 131 (2) ◽  
Author(s):  
O. Vahid ◽  
N. Eslaminasab ◽  
M. F. Golnaraghi
Keyword(s):  
Experimental Studies ◽  
Lead Screw ◽  
Axial Forces ◽  
Angular Velocities ◽  
Regions Of Stability ◽  
Identification Approach ◽  
Simulation Results ◽  
The Mathematical Model ◽  
Steady State Amplitude ◽  
Friction Induced Vibration

Lead screw mechanisms are used to convert rotary to linear motion. The velocity-dependent coefficient of friction at the contact between lead screw and nut threads can lead to self-excited vibrations, which may result in excessive noise generated by the system. In this paper, based on a practical example of a powered automotive seat adjuster, the nonlinear dynamics of lead screw systems is studied. A test setup is developed to perform experiments on the horizontal motion drive. The experimental results are used in a novel two-step identification approach to estimate friction, damping, and stiffness parameters of the system. The identified parameters together with other known system parameters are used in the numerical simulations. The accuracy of the mathematical model is validated by comparing numerical simulation results with actual measurements in cases where limit cycles are developed. Using simulation results for a range of lead screw angular velocities and axial forces, regions of stability were found. Also, the effects of damping and stiffness parameters on the steady-state amplitude of vibration were investigated.

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