bluuebunny/crossref_metadata_2025_split huggingface dataset:
Dynamics of Intermittent Sprays
Authors: Jawad Badih A. 
Published: December 2021

Abstract
It is considered that droplet size distribution changes with time and space, since diesel fuel sprays are found to be transient and intermittent due to variations in ambient pressures. Therefore the obscuration signal (extinction of light due to particle field) obtained from a particle sizer for a single injection of fuel over the whole region of spray is necessary to determine the spray characteristics. Previous studies dealing with sprays have observed fuel droplets by use of the sedimentation tower method or liquid immersion sampling technique. However, in these technique droplets are usually sampled after spray formation is complete. The completion time of spray formation appears to vary with ambient conditions, thus making spray measurements under transient conditions during injection difficult. It is the objective of this paper to shine some light on the dynamics of spray motion, leading to a better understanding of the droplet size distributions.
Three-Dimensional Numerical Modeling of Stoker-Fired Power Boilers
Authors: Dudek Scott A. , Wessel Richard A. , Strempek Joseph R. 
Published: December 2021

Abstract
A numerical model has been developed to simulate the various interacting physical processes that occur within any stoker-fired power boiler burning wood, refuse-derived fuel (RDF), coal, or other biomass fuel and operating at steady state. The processes modeled are three-dimensional turbulent gas flow, particle motion (including dispersion and re-entrainment), heterogeneous and homogeneous chemical reactions, and heat transfer. The purpose of this paper is to provide a detailed description of the model and to present an example of its use.
The model can be used as a cost-effective tool to assist in the design of original and retrofit power boiler equipment and in the diagnosis and resolution of boiler operating problems. The effects of modifying operational parameters or the physical arrangement of equipment can be quickly evaluated. Simulations can be used to optimize overfire air distribution and arrangement to produce a more uniform gas flow distribution within the furnace, resulting in more complete combustion and less particulate carryover.
As an example of the model’s capability, simulations were produced for a stoker-fired power boiler using wood, bark-pile reclaim, and waste-treatment sludge for fuel. The results show that changes in the air distribution and in the arrangement of operational overfire air ports can produce a significant reduction in carbon monoxide, unburned carbon loss, and particulate carryover, without increasing furnace exit gas temperature. Field modifications as a result of the modeling study have improved boiler operation and eliminated tube failures caused by flyash erosion.
Numerical Modeling of Combustion and Heat Transfer in a Laboratory Scale Glass Melting Furnace
Authors: Jorgensen K. L. , Ramadhyani S. , Viskanta R. 
Published: December 2021

Abstract
A fully three-dimensional model and computer code has been developed for predicting and analyzing combustion and heat transfer in the combustion space of glass melting furnaces. It is capable of predicting steady state temperature, velocity, and species concentration distributions throughout the combustion chamber and spatially resolving the heat transfer to the surrounding walls and the glass/batch surface. Model predictions are obtained from the solution of coupled conservation equations employing a control volume formulation. The discrete ordinates method along with the weighted-sum-of-gray gases model is used to determine radiative heat transfer to the surfaces enclosing the combustion space and within the flow field. Turbulence is modeled using a high Reynolds number k-ε model. A fast-kinetics, single-step combustion model using an assumed shape clipped Gaussian probability density function is used to determine gas species concentrations. The model predications are compared to test data from a laboratory scale glass furnace simulator at the Institute of Gas Technology. Comparisons of predicted quantities are made for wall temperatures, glass surface heat flux, and exit gas stream temperature. Wall and roof temperatures were predicted on average to within 7 percent and global heat fluxes were with in 10 percent of measured levels. Examples of predicted temperature, velocity, and species concentration are presented.
Radiation Heat Transport in Porous Media
Authors: Travkin V. S. , Catton I. 
Published: December 2021

Abstract
At present most work treats radiative transport in heterogeneous media as if it were a homogeneous medium, then relies on different methods to simulate the medium heterogeneity or uses similar governing equations with assigned distributions for coefficients. This approach is widely used although almost never found in other fields of heat and mass transport. The lack of generality in present theoretical treatments of radiative transport in heterogeneous media is addressed by rigorous development of a set of governing equations. The new rigorous equations for radiation transport in heterogeneous media are presented for the first time. As part of the development of the new set of equations for electromagnetic and spectral intensity fields, the diffusion approximation is explored.
Particle Transport via Three-Dimensional Chaotic Advection to Produce Electrically Conducting Plastics With Powder Additives
Authors: Danescu R. I. , Zumbrunnen D. A. 
Published: December 2021

Abstract
Extended micron-scale structures were produced in thermoplastic melts from initially large clusters of conducting carbon black particles transported by three-dimensional chaotic mixing. The structures formed networks that were captured by solidification and rendered the composite materials electrically conducting. A systematic study was carried out to assess the influence of key parameters and relate the electrical properties to the microstructures. Micrographs showed complex structures exhibiting patterns characteristic of chaos. Electrical measurements indicated that conductivity was achieved at carbon black concentrations significantly lower than achievable by common mixing methods, and lower than reported recently for two-dimensional chaotic mixing.
Photon Counting Temperature Measurements During Pulsed Laser Heating of Al2O3-TiC Ceramics
Authors: Harms Todd M. , Xu Xianfan 
Published: December 2021

Abstract
This work investigates photon-counting measurements during pulsed laser heating of an Al2O3-TiC substrate. The excitation source is a Nd:YAG laser operating at a fundamental wavelength of 1064 nm. The laser fluence is varied in the range from 0.272 J/cm2 to 0.839 J/cm2. The emission spectra, captured by single photon counting, are related to temperature by Planck’s distribution. The suitability of this method is discussed.
Pulse exposure, the number of pulses that a given surface location receives, is found to be a vitally important parameter. Numerical simulations of transient heat conduction support the results of high pulse exposure measurements. Low pulse exposure experiments exhibit higher temperatures due to chemical reactions at the surface and grain boundary effects.
3-D Sintering of Two-Component Metal Powders With Stationary and Moving Laser Beams
Authors: Zhang Yuwen , Faghri A. , Buckley C. W. , Bergman T. L. 
Published: December 2021

Abstract
Melting and resolidification of a mixture of two metal powders with significantly different melting points under irradiation of a stationary or a moving Gaussian laser beam were investigated numerically and experimentally. The liquid motion driven by capillary and gravity forces as well as the shrinkage of the powder bed caused by the overall density change were taken into account in the physical model. The liquid flow was formulated by using Darcy’s law, and the energy equation was given using a temperature transforming model. Predictions were compared with experimental results obtained with nickel braze and AISI 1018 steel powder. The effects of laser properties and the scanning velocity on the laser sintering process were also investigated. An empirical correlation that can be used to predict the of cross sectional area of the heat affected zone is proposed.
Transport Processes for a Row of Confined Jets Impinging on a Moving Surface
Authors: Dinu Constantin A. , Beasley Donald E. 
Published: December 2021

Abstract
The common architecture of the fluid delivery devices employed in the horizontal processing of printed wiring boards, makes use of high velocity jets directed normally or at some angle towards the board which moves above rollers. Usually, a single slot jet or a linear arrays of jets are employed in order to increase the transport properties of the flow in the vicinity of the printed wiring board. In the present study, a geometry resembling a fluid delivery device used in printed wiring board manufacturing was investigated both experimentally and numerically. The printed wiring board is represented by an endless belt, which is transported horizontally by a system of rollers. The working fluid is delivered by an array of 13 square jets with a hydraulic diameter of 5.02 mm and a separation distance between jets of 4 hydraulic diameters. Two confinement plates located on each side of the jet array are used to confine the flow region and adjust the flow resistance at the two openings — between the rollers and the confinement plates — symmetrically located with respect to the centerline of the row of jets. The experimental setup and the numerical model both allowed the investigation of the effect of complex confinement (due to the board, confinement plates and rollers) and of the moving boundaries (impingement surface and rollers) on the characteristics of impinging flow. The flow field and the heat transfer characteristics were investigated for the jet Reynolds number ranging from 500 to 2000, non-dimensional impingement surface velocity ranging from 0 to 1 and non-dimensional impingement distance of 3 and 5. The CFD simulations were performed using the commercial CFD code PHOENICS. Flow visualization and particle image velocimetry were employed in order to experimentally investigate the flow field and validate the CFD simulations. The predicted results compare well with the observed jet behavior. A detailed description of the flow physics is presented. The numerical simulations show that for the same mass flow rate, the row of jets has a higher transport effectiveness when compared to a slot jet.
Thermal Conductivity Measurement of CVD Diamond Films Using a Modified Thermal Comparator Method
Authors: Cheruparambil Kumar R. , Farouk Bakhtier , Yehoda Joseph E. , Macken Nelson A. 
Published: December 2021

Abstract
Results from an experimental study on the rapid measurement of thermal conductivity of chemical-vapor-deposited (CVD) diamond films are presented. The classical thermal comparator method has been used successfully for the measurement of thermal conductivity of bulk materials having high values of thermal resistance. Using samples of known thermal conductivity, a calibration curve is prepared. With this calibration curve, the comparator can be used to determine thermal conductivity of unknown samples. We have significantly modified and extended this technique for the measurement of materials with very low thermal resistance, i.e., CVD films with high thermal conductivity. In addition to the heated probe, the modified comparator employs a thermo-electric cooling element to increase conductive heat transfer through the film. The thermal conductivity measurements are sensitive to many other factors such as the thermal contact resistances, anisotropic material properties, surrounding air currents and temperature, and ambient humidity. A comprehensive numerical model was also developed to simulate the heat transfer process for the modified comparator. The simulations were used to develop a ‘numerical’ calibration curve that agreed well with the calibration curve obtained from our measurements. The modified method has been found to successfully measure the thermal conductivity of CVD diamond films.
Velocity Statistics of Plane Self-Preserving Buoyant Turbulent Adiabatic Wall Plumes
Authors: Sangras R. , Dai Z. , Faeth G. M. 
Published: December 2021

Abstract
Measurements of the velocity properties of plane buoyant turbulent adiabatic wall plumes (adiabatic wall plumes) are described, emphasizing conditions far from the source where self-preserving behavior is approximated. The experiments involved helium/air mixtures rising along a smooth, plane and vertical wall. Mean and fluctuating streamwise and cross stream velocities were measured using laser velocimetry. Self-preserving behavior was observed 92–156 source widths from the source, yielding smaller normalized plume widths and larger near-wall mean velocities than observations within the flow development region nearer to the source. Unlike earlier observations of concentration fluctuation intensities, which are unusually large due to effects of streamwise buoyant instabilities, velocity fluctuation intensities were comparable to values observed in nonbuoyant turbulent wall jets. The entrainment properties of the present flows approximated self-preserving behavior in spite of continued development of the wall boundary layer. Measurements of temporal power spectra and temporal and spatial integral scales of velocity fluctuations are also reported.
Higher-Order Discretization Method for Computations of Separated Flows
Authors: Song B. , Amano R. S. 
Published: December 2021

Abstract
This paper presents a new higher-order bounded scheme, WACEB, for approximating the convective fluxes in the transport equations. The weighted-average formulation is used for interpolating the variables at cell faces and the weighted-average coefficient is determined from normalized variable formulation and total variation diminishing (TVD) constrains to ensure the boundedness of solution. The new scheme is tested by solving three problems: 1) a pure convection of a box-shaped step profile in an oblique velocity field; 2) a sudden expansion of an oblique velocity field in a cavity, and; 3) a laminar flow over a fence. The results obtained by the present WACEB were compared with the UPWIND and the QUICK schemes and showed that this scheme has at least the second-order accuracy while ensuring boundedness of solutions. Moreover, it was demonstrated that this scheme produces results that better agree with the experimental data in comparison with other schemes.
Investigative Active Learning and the Teaching of Heat Transfer
Authors: Anderson Edward E. 
Published: December 2021

Abstract
The benefits and advantages of investigative active learning are well documented throughout cognition and educational psychology research literature. But, these techniques are not extensively used in higher education and particularly engineering education. In this paper, a model is presented for applying computer based instruction (CBI) techniques to investigative active learning as practiced in a typical undergraduate heat transfer course. This model is demonstrated with the heat transfer through a composite structural wall problem. An investigative approach is used to coach students as they learn the general solution process. Several different active learning techniques are then applied as a student progresses through each step of the general solution process. These techniques are applicable to any heat transfer problem and when properly implemented, they should improve the learning of the general solution process. The demonstration example is best experienced with a computer. Individuals wishing to explore this model may do so at http://129.118.17.180/mvweb.
Response of Loop Heat Pipes to Transient Heat Loads
Authors: Long J. B. , Ochterbeck J. M. 
Published: December 2021

Abstract
Loop heat pipes currently are being used in the thermal control systems for satellites. To expand possible loop heat pipe applications, information regarding response to transient heat inputs is required. In this investigation, two loop heat pipes with dual compensation chambers were subjected to heat inputs of varying magnitude, frequency, and waveform (square and sinusoidal). The performance of each loop heat pipe under these conditions was evaluated in different gravitational orientations. The upper and lower limits of heat transport also were assessed. A principle finding was that cyclic heat loads tended to aid startup of the loop heat pipes at the low power inputs.
Overview of U.S. Process Safety Regulations and ANSI/ISA S84.01 for an Integrated Risk Program
Authors: Doerr William W. , Bhimavarapu Kumar 
Published: December 2021

Abstract
In response to major chemical and nuclear accidents that have occurred during the past two decades, the U.S. government has promulgated two regulations aimed at protecting workers, the community, and the environment from accidental releases of hazardous chemicals. These regulations are the US Occupational Safety & Health Administration’s [OSHA] Process Safety Management [PSM] Standard and the US Environmental Protection Agency’s [EPA] Risk Management Program [RMP]. The applicability for each regulation is discussed with a review of what is affected, who is responsible, when is compliance required, and how is compliance manifested. In addition, the recent ANSI/ISA S84.01 standard for the process industries introduces additional or new responsibilities that are not featured explicitly in either the OSHA or EPA regulations. The pooling of the requirements from these US regulations and voluntary ANSI/ISA standard establishes the requirements for an integrated risk program [IRP]. The objective of an integrated risk program is compliance, reduction in resource requirements, and improvement of productivity at a plant. The general requirements for an IRP are summarized showing the area of regulatory overlap.
A New Interlock System: Movable Interlocked Barrier Guards With Motorized Openers for Testing
Authors: Barnett Ralph L. , Liber Theodore 
Published: December 2021

Abstract
A unique system is introduced for monitoring the viability of conventional position switch interlocks on movable barrier guards. At closely spaced intervals a test device motor causes the guard to open slightly to check if the interlock will change state in an attempt to interrupt control power to the protected machine. The machine will not in fact shut down during the testing phase because the interlock system will be isolated from the machine operating motor contactors during the test duration. Testing of a guard is annunciated just before and during the automatic testing phase. Any failures of an interlock or its testing system will also be annunciated until their causes are corrected. When a latching system is used in conjunction with the guard, a faulty interlock will cause the guard to be locked closed until it is convenient to effect a repair. Production is not interrupted because the interlock remains bypassed during this period. If an interlock is temporarily circumvented or if the interlock guard is sabotaged, the test device motor will not cause a change in state of the interlock during the test phase; again, system malfunction will be annunciated and/or the guard will remain latched and/or the machine will be shut down.
The proposed process provides the following advantages:
• A quantum leap in system reliability and safety is obtained using even the most ordinary “limit switch” type interlocks.
• The tamper-resistance of all known interlocks will be greatly enhanced; all popular forms of temporary interlock circumvention are eliminated.
• Long term sabotage which involves simultaneous guard removal and interlock bypassing is addressed for the first time; to defeat the proposed process involves the most outrageous restructuring of the control system.
• The system will safely endure adhesive environments that may cause interlock activators to stick in their “fail to danger” states.
• The monitored machine is almost never shut down nor production interrupted during or after the testing phase even if mischief is uncovered.
• The testing of large numbers of interlocks will not expose the machines’ electric power motors to the frequent restart demand associated with some conventional manual testing procedures.
• Without compromising safety, maintenance of even multiple interlock failures may be deferred until their repair is convenient.
• The assurance of working interlocks may enable OSHA to expand applications where maintenance is performed under “control stop” as opposed to the more elaborate “lock out.”
• The design of the new test and monitoring system may be executed and implemented using straightforward hardware and software that are firmly entrenched technology.
Influence of the Dynamic Wetting Angle on the Motion of the Triple Line
Authors: Woehl Pierre , Bourgin Patrick 
Published: December 2021

Abstract
The problem of a liquid sheet issuing from an ejector and being coated on a moving solid substrate is considered in taking into account the dynamic behavior of the ambient air. In a previous model, we investigated the possible influence of slight pressure fluctuations in the air on the displacements of the triple line. We propose here to incorporate into our model a non-linear dependence of the dynamic contact angle upon the triple line velocity, in order to be more consistent with the experimental observations reported in the literature.
The main result is that the motion of the triple line induced by pressure oscillations in the air is very sensitive to the dependence of the dynamic wetting angle on its velocity. The respective roles of the liquide wetting properties and of the process conditions are pointed out.
Two Dimensional Transient Thermal Stress Analysis of Adhesive Butt Joints
Authors: Nakano Yuichi , Kondo Hiroki 
Published: December 2021

Abstract
Transient thermal stress distribution in an adhesive butt joint is dealt with in this study. It is assumed that both the upper and lower end surfaces of the joint are subjected to different temperatures at a certain instant in time and the side surfaces of the joint are kept at a constant temperature. In the analysis, two adherends and an adhesive layer are replaced with finite strips and unsteady, two-dimensional temperature distribution in the joint is obtained theoretically. Then, the transient thermal stress distribution in the joint is analyzed using a two-dimensional theory of elasticity. The effects of the adherend to adhesive ratios of the Young’s moduli and thermal expansion coefficients on the transient thermal stress distribution are clarified using numerical calculations.
Elasto-Plastic Analysis of Bolted Joint During Tightening Process
Authors: Fukuoka Toshimichi , Takaki Tomohiro 
Published: December 2021

Abstract
A bolted joint is subjected to high stress concentration at the thread root because of its complicated geometry involved. Plastic regions are produced around the bottom of thread root, even under relatively low bolt axial force. It is predicted that the plastic deformation thus produced might affect such important mechanical behaviors of bolted joint as load distributions along threads, the relationships between bolt axial force and angle of nut rotation, etc. In many practical applications, bolts are tightened with considerably high clamping force, especially when tightening critical structures. Thus, it is considered that numerical studies taking the effects of plastic deformation into account are extremely important. However, many previous studies have only dealt with a bolted joint under pure tension. When tightening bolted joints with torque control shear stresses are generated in addition to the tensile stress due to bolt clamping force. In this study, mechanical behaviors of bolted joint during tightening with torque control are analyzed by FEM as an elasto-plastic contact problem, where three-dimensional analysis is conducted employing two dimensional model with each node having three degrees of freedom.