bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Study of Intermittent Flow in Downward Inclined Pipes
Authors: Yang Jiede , Sarica Cem , Chen Xuanzheng , Brill James P. 
Published: July 2023

Abstract
The downward simultaneous flow of gas and liquid is often encountered in hilly terrain pipelines and steam injection wells. Most of the available methods for predicting the behavior of gas-liquid flow in pipes have been developed for horizontal and upward inclined pipes. In this study, co-current steady state slug flow in downward inclined pipes is investigated, experimentally and theoretically. A series of slug flow experiments are conducted with an air-kerosene system in a 2-in. diameter, 75-ft long pipe installed on an inclinable structure. Liquid holdup and pressure drop measurements are obtained for downward inclination angles from 0° to −90° at different flow conditions. Correlations for slug flow characteristics are obtained based on the experimental data. A mechanistic model based on a unit cell approach has been proposed for the prediction of the detailed slug structure, and subsequently the pressure gradient.
Fully developed slug flow could not be observed from −50° to −90°. A correlation was obtained for slug liquid holdup, and an analytical model and a correlation were developed for slug translational velocity. The lognormal distribution was found to best fit all the experimental slug length data. Equations for mean and design slug length were derived from the lognormal distribution function for inclination angles ranging from 0° to −30°. A slug frequency correlation was also developed.
The model can be used to predict intermittent flow behavior in downward inclined pipes. The correlations for slug liquid holdup, slug translational velocity, and slug length and frequency are closure relationships applicable to any model. Slug frequency information is also imperative for erosion and corrosion rate predictions.
Experimental Study on PORV Stuck-Open Accident in INER Integral System Test Facility
Authors: Liu T. J. , Lee C. H. , Hong W. T. , Chan Y. K. , Chang C. Y. 
Published: July 2023

Abstract
Four scaled small break loss-of-coolant accident (LOCA) tests simulating the pressurizer power-operated relief valve (PORV) stuck-open accidents and the recovery actions in a pressurized water reactor (PWR) were performed at the INER Integral System Test (IIST) facility. The objectives of this study are to verify the effectiveness of emergency operating procedure and emergency core cooling system on reactor safety. The break sizes were volumetrically scaled down based on one and all three fully-opened PORVs which is equivalent to 0.46% and 1.37% cold leg flow area. The experimental results indicate that in case of high pressure injection (HPI) system failure, the rapid depressurization of the steam generators is proved to be an effective way in the depressurization of the reactor coolant system and the core cooling. If the high pressure safety injection operates normally, the core cooling can be adequately provided without operating the secondary bleeding during PORV stuck-open transient.
Experimental Study of Flow Instability and CHF in a Natural Circulation System With Subcooled Boiling
Authors: Yang Rui C. , Shi De Q. , Lu Zhong Q. , Zheng Rong C. , Wang Yong 
Published: July 2023

Abstract
Experimental study has been performed to investigate flow instability and critical heat flux (CHF) in a natural circulation system with subcooled boiling. In the experiments three kinds of heated sections were used. Freon-12 was used as the working medium. The experiments show that which one of the two phenomena, flow instability and CHF condition, may first occur in the system depends on not only the heat input power to the heated section and the parameters of the working medium, but also the construction of the heated section. The occurrence of the flow instability mainly depends on the total heat input power to the heated section and the CHF condition is mainly caused by the local heat flux of the heated section. In the experiments two kinds of flow instability, flow instability with high frequency and flow instability with low frequency, were found. But they all belong to density wave instability. The influence of the parameters of the working medium on the onset of the flow instability and CHF condition in the system were investigated. The stability boundaries were determined through the experiments. By means of dimensional analysis of integral equations, a common correlation describing the threshold condition of onset of the flow instability was obtained.
Experimental Study of Phase Separation in Dividing Two Phase Flow
Authors: Yong Qian , Zhilin Yang , Jijun Xu 
Published: July 2023

Abstract
Experimental study of phase separation of air-water two phase bubbly, slug flow in the horizontal T-junction is carried out, the influences of the inlet mass quality XI, mass extraction rate G3/G1, and fraction of extracted liquid QL3/QL1 on phase separation characteristics are analyzed. For the first time, we have found and defined “Pulsating run effect” by the visual experiments, which show that under certain conditions, the down stream flow of the T-junction has strangely affected the phase redistribution of junction, and firstly point out that the downstream geometric condition is very important to the study of phase separation phenomenon of two-phase flow in T-junction.
Multi-Mode Methanol Flow Boiling Under Atmospheric and Subatmospheric Pressures
Authors: Lin W. W. , Liao Y. C. , Lee D. J. 
Published: July 2023

Abstract
This is a continuation work of Lin and Lee (1996 National Heat Transfer Conference, Houston) while reporting the experimental results of multi-mode methanol How boiling under atmospheric and subatmospheric pressures. An axial (discrete) heat flux distribution with neutral stability at which nucleate and film boiling can coexist steadily is identified under various system pressures and crossflow rates. Below this heat flux distribution, nucleate boiling mode is more stable. Above this distribution, film boiling becomes the more stable mode. An equal-area criterion based on the difference between bottom heat flux and surface boiling heat flux, and the wall superheat temperature relationship is employed for interpreting the experimental data. Effects of system pressure, mass flowrate, liquid subcooling and bottom heat flux on the relative stability of nucleate and film boiling modes are discussed.
Flow Patterns and Their Transitions of Vertically Downward Two-Phase Flow With High Viscosity Liquid
Authors: Wang Shu-Zhong , Lin Zong-Hu , Liang Zhi-Peng 
Published: July 2023

Abstract
The flow patterns and their transitions of air-oil two-phase flows in a vertically downward pipe were investigated experimentally and theoretically. The pipe diameter was 29mm, and the oil and air superficial velocity were up to 4m/s and 20m/s respectively. The flow pattern identifications were carried out by means of the combination of visual observations and analysis for corresponding pressure drop pulsation signals. The investigations express that the flow patterns and their transitions of oil and gas two-phase flow somewhat differed from those of low viscous liquid and gas two-phase flows. On the basis of this study and other previous investigations, one available approach is presented to predict the flow patterns and their transitions in vertically downward two-phase flow with high-viscosity liquid.
Drying of a Moist Porous Medium by Bulk Flow of Gas
Authors: Chen Y.-T. , Boehm R. F. 
Published: July 2023

Abstract
A model has been developed to describe the heat and mass transfer that occurs in the drying of a porous medium due to the bulk flow of a gas. This model is formulated in one dimension and describes the convective and evaporative phenomena that occur in an initially residually-saturated medium. Comparisons are made between the model and an experiment that resembles the modeled geometry. Temperature-versus-time and exiting-humidity-versus-time plots are given in the paper for two different thermal boundary conditions. Generally good agreement is shown between the model and experimental results. However, it is concluded that the rate of mass transfer manifest in the experiment may be greater than that represented in the model. Another artifact of the results is that there are some changes in slope in the experimental curve showing the exiting relative humidity that are not seen in the calculations. It is concluded that these may be due to non-uniform packing of the bed.
A General Governing Equation for Flow of Fluids in Porous Media
Authors: Moaveni Saeed 
Published: July 2023

Abstract
A general differential equation governing the motion of a fluid through porous media is formulated by applying the momentum balance to a formal control volume. The porous medium in the control volume is modeled as an assemblage bundle of hypothetical conduits through which fluid is transported across the medium. The momentum equation employed, will account for the rate of momentum influx and efflux by virtue of the bulk fluid motion in and out of control volume. This formulation will also take into consideration a net shear force acting on the surface of the control volume. The pressure forces acting on the fluid surfaces of the volume element and the resultant viscous force of the fluid acting on the interior wetted surfaces of hypothetical conduits are also included in the model. Furthermore, it is shown that equation of motion reduces to the familiar Darcy’s Law for slow flow rates; for higher velocities, it transforms into Forchheimer relationship. For non-uniform velocity fields, the governing equation yields additional cross-stream-inertia term and a drag term which do not appear in other formulations. In the absence of inertia effects, the derived equation of motion reduces to Brinkman’s findings. In addition, the individual coefficients of the expressions in the momentum equation are explicitly derived in terms of fluid properties, size characteristics of a given medium and some unknown coefficients. A procedure for extracting the unknown coefficients will also be discussed.
Numerical Simulation of Laminar Film Boiling Heat Transfer From Vertically Suspended Smooth Surfaces in Cryogenic Fluids Subjected to Constant Wall Heat Flux
Authors: Akyuzlu K. M. , Malipeddi S. 
Published: July 2023

Abstract
This study is aimed at solving the one-field conservation of mass, momentum, and energy equations for laminar film boiling from vertically suspended smooth surfaces in cryogenic fluids subjected to constant wall heat flux boundary condition. Solutions to the problem of laminar film boiling under constant wall temperature boundary condition have been obtained in the past using analytical and iterative techniques. Here, the governing equations are solved under constant heat flux boundary condition using an analytical method supplemented with curve fitting techniques. The procedure is iterative because it assumes the vapor film thickness to start the calculations and then uses the energy equation at the interface to check the accuracy of this assumption. A computer program was developed to integrate this iterative procedure with a scheme that repeats the calculations at different discrete locations along the heated surface to estimate the laminar film thickness and to generate the velocity and the temperature profiles within the film boundary. The numerical results are compared to the experimental results for a stainless steel plate vertically suspended in liquid nitrogen where the plate is heated by constant current. The numerical predictions are matched with the experimental results by using a calibration parameter that relates various properties of the liquid and the vapor.
Measurement of Temperature, Concentration, and Velocity in Laminar Flow Using a Single Wire Probe
Authors: Nakabeppu Osamu , Kinoshita Atsuo , Hijikata Kunio 
Published: July 2023

Abstract
The measurement of three physical quantities: temperature, concentration and velocity in laminar flow using a single metal wire probe with an applied AC voltage was studied. The measurement setup is simple; it contains a thin metal wire, a bridge circuit and a lock-in amplifier. Furthermore its operation is very straight forward, thus it is a useful technique for heat and mass transfer research and monitoring of industrial processes. For the temperaure and velocity measurement the same principle used in the RTD and hot wire anemometer method is applied in AC mode. Whereas the 3w method was used for concentration measurement in forced convection. Measurement condition and performance is discussed for each measurement. Using a measurement example for flow composed of two liquids in a rectangle channel, it is shown that profiles of three physical quantities are measured like what is expected by this method, however the velocity and concentration measurement are delicate and improvement of accuracy is necessary.
Applications of Two-State M-Integral to a Triple Junction Vertex Under Thermal Loading
Authors: Im Seyoung , Jeon Insu 
Published: July 2023

Abstract
The two-state M-integral, which is derived from the M-integral and is applicable for two elastic states, is applied for computing an intensity of a singular near-tip field around the vertex of a triple junction of three different materials under thermal loading, often encountered in electronic packaging. Numerically we verify that a simple auxiliary field associated with every eigenfunction for the composite wedge under consideration exists in the form of the conjugate solution in the sense of the M-integral. The auxiliary field is then employed for superposition with the elastic field under consideration, and the associated two-state M-integral is computed via the domain integral technique. This enables us to extract the intensity for a leading singular eigenfunction. The proposed computational scheme enjoys the efficiency and simplicity in that the near-field information for a singular elastic boundary layer is extracted from the domain integral representation without resort to singular finite elements for the wedge vertex.
On Analysis of Discrete Systems With Variable Structure
Authors: Gavrilov Dmitri , Vinogradov Oleg 
Published: July 2023

Abstract
In many applications a discrete system undergoes structural (or connectivity) changes when subjected to loads or deformations. Each time the connectivity between the discrete elements changes a new system of equations must be generated and solved. In the paper a new method based on the numerically generated inverse matrix for the entire system allows the updating of the latter after each change in connectivity instead of generation and recalculation of the new system of equations. The method is symmetrical with respect to addition and elimination of links. The presented algorithm is based on recursive relationships between the inverse matrices for two systems differing by one element. The method is demonstrated for plane granular clusters, i.e. systems of particles bound together and having zero internal degrees of freedom, which is equivalent to any overconstrained system comprising the two-node finite elements. The problems of numerical efficiency and accuracy of the method are discussed and demonstrated on numerical examples.
Failure Mechanisms of a Ceramic-Metal Interface Under the Application of High Temperature Loading
Authors: Zarzour Joseph F. , Onesto Eugene J. 
Published: July 2023

Abstract
Controlled experiments with a thermal spray coating of aluminum oxide (alumina) on high purity nickel metal base were carried out to examine the mechanisms of cracking and delamination. Control of these phenomena will enhance the life of thermally sprayed components subjected to thermal shock. These experiments along with computer models will advance the fundamental understanding of this ceramic-metal interface. A plasma spray torch was used to prepare the test specimens, and a high power radiative furnace was used to apply a thermal shock load to the specimens during testing. Geometric effects studied include thickness ratio, thickness to diameter ratio, absolute coating thickness, and the effect of a peak temperature.
Experimental results show that using the same critical thermal cycle, specimens with 1mm thick coating failed by cracking, specimens with coating thickness below 1mm did not show any type of failures, and specimens with coating thickness higher than 1mm failed by spallation inside the coating layer.
A finite element model incorporating the rate-dependent inelastic behavior of nickel at high temperature was developed to provide a realistic estimate of the residual stresses that develop during the thermal cycle. From transient heating to room temperature cooling, residual stress gradient from compressive to tensile was observed in the coating layer. With decreased coating thickness, this phenomenon was less pronounced.
An Optimization Technique Using the Finite Element Method and Orthogonal Arrays
Authors: Young Stuart H. , Kwon Young W. 
Published: July 2023

Abstract
The objective of this research was to develop an optimization technique that can be used interactively by design engineers to approach an optimal design with minimal computational effort. The technique can be applied to both continuous and discrete values of design variables. A large number of design variables can be also considered.
In order to meet the objective, an optimization procedure was developed by coupling the finite element analysis (FEA) to the orthogonal array experimentation technique, because FEA is a common analysis tool for design engineers. From the results of the FEA and an orthogonal array, an average Jacobian matrix was constructed that showed the average overall sensitivity of the design variables. These sensitivities were then used to optimize the design parameters. The process could then be repeated at the discretion of the engineer until he was satisfied with the design. In general, the designer can predict and control the number of FEA calculations before an optimization process so that he can plan a budget and time for an optimal design.
Some examples of structural optimization with truss structures with continuous and discrete values of design variables were studied using the technique developed in this paper. Their optimal solutions were found with small numbers of iterations.
Bifurcation and Postbuckling Response of Asymmetric Laminated Columns
Authors: Vinogradov Aleksandra M. , Derrick William R. , Keck Andrew G. 
Published: July 2023

Abstract
The paper concerns the buckling and postbuckling response of laminated composite columns with arbitrary material lay-ups. The objective of the study is to examine the joint effects of bending-stretching couplings and initial imperfections on the nonlinear buckling behavior of irregular asymmetric laminates. In the paper, the analysis is focused on the nonlinear buckling problem of eccentrically loaded composite columns composed of n isotropic elastic layers. The response of such columns is examined over a range of structural parameters leading to several conclusions regarding the typical buckling characteristics and optimization of asymmetric laminates.
Stiffness Enhancement of Metallic Beam-Like Components
Authors: Rivin Eugene I. , Pankach Panchal 
Published: July 2023

Abstract
Stiffness is an important design criterion. Since bending deformations of structural components are much larger than tension/compression deformations under comparable loads, enhancement of bending stiffness of beam-like components is an important problem. Conventional techniques for stiffness enhancement (beefing up, optimization, use of high Young’s modulus materials) frequently do not achieve the desired results. The paper describes a novel approach to bending stiffness enhancement based on the inverse buckling effect. The beam is composed of the structural external member having an axial hole which is plugged and filled with a fusible metal alloy expanding during solidification thus stretching the external member and enhancing its stiffness. Experimental study resulting in 40% increase in bending stiffness is described.
Simulated Metallic Structures for Use in Radar Measurements
Authors: Barclay Jeffrey J. 
Published: July 2023

Abstract
The Naval Undersea Warfare Center, Division Newport has been active in quantifying radar signatures of periscopes, communication masts, and sensors, as well as different materials. Development of computational prediction codes, along with radar measurements of various targets, have provided the primary analysis tools in signature management. Because of the nature of these radar measurements, techniques were developed to simulate metallic structures. With these techniques, manufacturing time and cost were greatly reduced along with large reductions in structure weight. These techniques primarily used electrically conducting tape and paint as coatings to simulate a metallic, electrically conducting surface. Simulation validation, with computational code, was achieved with the production and measurement of several simulated metallic structures. By achieving this validation, reasonable geometrical design changes could be developed and studied with computational predictions. The most recent experiment involved using a simulated metallic surface to provide an entire environment for the targets under test. Again by using these metallic coated structures to create a multipath environment, expense and manufacturing time were reduced. This simulated environment will, it is hoped, provide a very controllable and repeatable measurement tool for incoherent scattering and fully polarimetric studies of a multipath environment.
Computational and Laboratory Analysis of Thermal Free-Form Fabrication of Metal Prototypes
Authors: Doumanidis Charalabos , Fourligkas Nikolaos 
Published: July 2023

Abstract
The advent of rapid prototyping methods for functional layered metal products has created the need for thermal off-line analysis and optimization of the process conditions, as well as for real-time control of the material structure and properties through the temperature field. For this purpose, this work introduces a scanned thermal processing technique, in which the heat source rapidly sweeps the surface of each deposited layer to ensure a flexible heat input distribution. For this method, the article establishes two dynamic thermal modeling tools: a finite-difference numerical simulation of the temperature field in layered objects, and an experimental linearized formulation with time-varying parameters identifiable in-process by thermal measurements. The models are applied and validated in elementary LOM thermal operations on a plasma-arc processing station with infrared thermal sensing and computer control, and their use for design of a closed-loop thermal regulator is discussed, together with the metal structure and properties of scanned parts.
Fracture Mechanics Approaches to the Prediction of Fatigue Life of a Beta Titanium Alloy (Ti-15V-3Cr-3Al-3Sn)
Authors: Rabeeh Bakr M. , Soboyejo Alfred. B. , Rokhlin Stanislav I. , Soboyejo Wolé 
Published: July 2023

Abstract
This paper highlight the results of recent efforts to develop mechanistically based, fracture mechanics models, for the prediction of the total fatigue life in Ti-15V-3Cr-3Al-3Sn (Ti-15-3). Acoustic emission techniques and visual observation (light and scanning electron microscopy) methods are used to monitor fatigue initiation and propagation phenomena in Ti-15-3. Mechanistically-based fracture mechanics idealizations of initiation and propagation stages are then formulated for the prediction of fatigue life. Using the measured initial crack length as the key variable in fatigue life prediction equations, the bounds in the predicted initiation and propagation lives are estimated using fracture mechanics techniques. The paper highlights the advantages of simplified fracture mechanics methods in the prediction of fatigue life.