bluuebunny/crossref_metadata_2025_split huggingface dataset:
Simultaneous Determination of Temperature-Dependent Thermal Conductivity and Volumetric Heat Capacity by an Inverse Technique
Authors: Woodbury Keith A. , Boohaker Charles G. 
Published: July 2023

Abstract
Determination of thermal properties by inverse methods often involves limited thermal excitation of a relatively small sample. If these thermal properties are to be found as functions of temperature, then this procedure must be replicated at several artificially elevated temperatures. For some types of materials (for example, those bearing moisture) this approach is impractical.
In this paper, a procedure is developed for determining thermal properties (conductivity k and volumetric heat capacity C ≡ ρcp) as functions of temperature from a single experiment. This procedure is targeted for determination of k(T) and C(T) for sand molds used in castings. An inverse method based on a Gauss linearization is used to estimate these functions.
The experiment used to determine these properties consists of heating a one-dimensional specimen of the material from one end. The variation of thermal properties with temperature is assumed to be a piecewise linear function, with values of properties to be determined at prescribed temperatures.
A numerical experiment is used to demonstrate the technique.
Local Heat Transfer Distributions in a Square Channel With Solid and Perforated Ribs on Two Opposite Walls
Authors: Kukreja Rajesh T. , Lau Sai C. 
Published: July 2023

Abstract
In this experimental investigation, the variations of the local heat transfer coefficient in rib-roughened turbine blade internal cooling passages are examined. Using liquid crystal thermometry, the detailed local heat transfer distributions are determined for turbulent flow through a long, straight, square test channel model with ribs of various configurations, including perforated ribs, on two opposite walls.
Angled and V-shaped solid ribs enhance more heat transfer than transverse solid ribs. Angled solid ribs cause very large spanwise variations of the local heat transfer distribution. With the highest overall heat transfer and relatively small spanwise heat transfer variation, V-shaped ribs are recommended for internal cooling of gas turbine blades. Perforated ribs enhance less heat transfer than solid ribs, because the jet streams leaving the holes interrupt and weaken flow reattachment on the wall downstream of a rib. Increasing the size or the number of holes, or the total hole area, lowers the overall heat transfer.
Turbulent Natural Convection Along a Vertical Backward-Facing Step
Authors: Yuan X. , Chen T. S. , Armaly B. F. 
Published: July 2023

Abstract
Flow separation with reattachment occurs in many flows of practical interest. In this paper a two-equation turbulence model by Ince and Launder (1989) with Yap correction and a four-equation turbulence model by Abe et al. (1995) are utilized to predict turbulent natural convection along a vertical backward-facing step. Numerical computations were performed for a Prandtl number of 0.7 for three step heights (1.1, 2.2 and 4.4 cm) and with a temperature difference of 30°C between the heated plates and the free stream. Results are presented for mean flow velocity and temperature distributions, turbulence kinetic energy and its dissipation rate, turbulent heat flux, intensity of turbulent temperature variance and its dissipation rate, local Nusselt number, and reattachment length. A comparison between the predicted results from the two turbulence models shows that the differences in the maximum Nusselt number and in the reattachment length range, respectively, from 4% to 24% and 10% to 2% as the step height increases from 1.1 to 4.4 cm.
Effects of Bubble Motion on Chord Length Measured by Double-Needle Conductance Probe
Authors: Monji Hideaki , Matsui Goichi 
Published: July 2023

Abstract
This study deals with effects of bubble motion on average chord length of bubbles measured by a double-needle type conductance probe system. So far, known estimation methods for bubble size are restricted to only a spherical bubble. For the estimation of deformed bubble size, the rocking motion of a bubble should be considered. Furthermore, in order to obtain the value of bubble size near the wall, the relation between the size and average chord length of bubbles should be derived taking both the restricted bubble motion and the probe position into account. The results show that taking the rocking motion of a bubble into account, the bubble size is estimated accurately for an oblate spheroidal bubble, and that the restriction of the bubble motion by the wall induces the peak in the chord length distribution, even if the bubble size is uniform.
Flow Boiling Inside Enhanced Heat Transfer Tubes
Authors: Xiang G. M. , Hu H. Y. , Peng X. F. , Wang B. X. 
Published: July 2023

Abstract
A tube with longitudinal microchannels on inside wall was developed to enhance flow boiling heat transfer. The experimental investigation was conducted to identify the flow boiling heat transfer performance of liquid through the enhanced tubes. The flow boiling heat transfer in the enhanced tubes is greatly intensified, especially for the fully-developed nucleate boiling regime. The heat transfer coefficient in microchanneled tubes with smaller diameter is increased with a magnitude of 170% compared with the identical smooth tubes. The geometric configuration of microchannels and tubes would have significant effect of the flow boiling inside microchanneled tubes. The heat transfer performance of the microchanneled tubes is as good as or even better than that of other existing enhanced tubes.
Mixed Convective Heat Transfer for Fluid Flowing Through Annular Porous Medium
Authors: Wang B. X. , Du J. H. , Peng X. F. 
Published: July 2023

Abstract
The study of the transport phenomena in porous media provides the fundamentals for various branches of science and engineering. We have reported currently on our researches on the fluid flow and convective heat transfer in porous media. The entrance and non-Darcy’s effects on the forced and mixed convective heat transfer were studied experimentally for air, water and transformer-oil flowing through a vertical annulus packed with porous media beads of different sizes. The results are reported and discussed here briefly.
Experimental Study on Flow Rate Measurement by Using Cross-Correlation of Temperature Fluctuations
Authors: Sun Xiaodong , Dai Zhenxi , Weng Yihao , Xu Jijun 
Published: July 2023

Abstract
The applicability of cross-correlation method based on fluid temperature fluctuations to flow rate measurement under steady flow condition is investigated with experiments by using an on-line, digital instrument developed by the authors. The thermocouple transducer design, the signal data pre-processing system and the correlator design with chip microprocessor 8031 are described. The experimental results show that the intrinsic temperature fluctuations existing naturally in flowing fluid are adequate to be detected. The method is proved to be a reliable and accurate one of flow rate measurement in turbulent flow. In laminar flow, the measurement is not so satisfactory.
Numerical Study of Flow in Gas-Stirred Ladle Systems With and Without Throughflow
Authors: Park Hee-Jin , Yang Wen-Jei 
Published: July 2023

Abstract
Two turbulent models, the conventional k-ε and Reynolds Stress models, are employed to simulate turbulent recirculating two-phase flow generated by air injection to a ladle with or without throughflow. A Lagrangian-Eulerian scheme for two phases is computed numerically. It is shown that the k-ε model, while overpredicting turbulent kinetic energy, underpredicts the mean velocity of the Reynolds Stress model. It is also disclosed that the dispersion rate of a plume is more dependent on the bubble flow-rate than on the bubble size. The location of the air injection nozzle is varied for the throughflow case. It is shown that the k-ε model is not suitable for predicting highly swirling flow, even though it yields results which are in agreement with measurements in less swirling flow. It is also revealed that air injection from the left bottom nozzle is more effective in reducing the zone of zero turbulent kinetic energy which results in poor mixing.
A Numerical Simulation of the Solidification Process of a Binary Mixture in a V-Shaped Enclosure
Authors: Jones W. K. , DeZego S. E. , Dong Z. F. , Ebadian M. A. 
Published: July 2023

Abstract
A numerical study of the solidification process in a V-shaped sump has been conducted for a binary mixture. This geometry is of particular interest as it simulates the limiting cases of the physical domain of the molten metal in the direct chill (DC) continuous casting process. Solutions were obtained by solving a two-phase set of conservation equations of mass, momentum, energy, and species in a polar coordinate system. The necessary interfacial terms for the two-phase model are discussed. A non-uniform grid, biased at the point discontinuity, was chosen for the calculations to improve the stability of the numerical procedure. The binary mixture studied was a eutectic forming aluminum-copper (Al-Cu) alloy. Two limiting cases of sump angle (8° and 16°) were simulated to gain insight into the influence of geometric effects on the final cast properties. The effects of melt convection and solid movement are also discussed as contributing factors to the segregation patterns. The results of the study showed the angle of the enclosure greatly affected the developing negative segregation bands in the mushy region. Furthermore, the original negative-segregated mushy zone gradually developed into a positively-segregated region throughout the solid area.
Experimental Investigation of a Bubbly Flow by Means of an Image Analysis Technique
Authors: Schmidl William D. , Hassan Yassin A. , Ortiz-Villafuerte Javier 
Published: July 2023

Abstract
Particle Image Velocimetry (PIV) is a non-intrusive measurement technique, which can be used to study the structure of various fluid flows. PIV is used to measure the time varying full field velocity data of a particle-seeded flow field within either a two-dimensional plane or three-dimensional volume. PIV is a very efficient measurement technique since it can obtain both qualitative and quantitative spatial information about the flow field being studied. This information can be further processed into information such as vorticity and pathlines. Other flow measurement techniques (Laser Doppler Velocimetry, Hot Wire Anemometry, etc..) only provide quantitative information at a single point.
PIV can be used to study turbulence structures if a sufficient amount of data can be acquired and analyzed, and it can also be extended to study two-phase flows if both phases can be distinguished. In this study, the flow structure around a bubble rising in a pipe filled with water was studied in three-dimensions. The velocity of the rising bubble and the velocity field of the surrounding water was measured. Then the turbulence intensities and Reynolds stresses were calculated from the experimental data.
Heat Transfer Characteristics for Some Coolant Additives Used for Water Cooled Engines
Authors: Abou-Ziyan Hosny Z. , Helali Abdel-Hamid B. 
Published: July 2023

Abstract
Engine coolants contain certain additives to prevent engine overheating or coolant freezing in cold environments. Coolants, also, contain corrosion and rust inhibitors, among other additives. As most engines are using engine cooling solutions; it is of interest to evaluate the effect of engine coolants on the boiling heat transfer coefficient. This has its direct impact on radiator size and environment.
This paper describes the apparatus and the measurement techniques. Also, it presents the obtained boiling heat transfer results at different parameters. Three types of engine coolants and their mixtures in distilled water are evaluated, under sub-cooled and saturated boiling conditions. A profound effect of the presence of additives in the coolant, on heat transfer, was clear since changes of heat transfer for different coolants were likely to occur. The results showed that up to 180% improvement of boiling heat transfer coefficient is experienced with some types of coolants. However, at certain concentrations other coolants provide deterioration or no enhancement in the boiling heat transfer characteristics. This investigation proved that there are limitations, which are to be taken into consideration, for the composition of engine coolants in different environments. In warm climates, ethylene glycol should be kept at the minimum concentration required for desolving other components, whereas borax is beneficial to the enhancement of the heat transfer characteristics.
Studies of Artificial Cracks at Simulated Rocket Motor Liners by the Frozen Stress Method
Authors: Smith C. W. , Finlayson E. F. , Liu C. T. 
Published: July 2023

Abstract
Two types of bimaterial specimens, one consisting of two photoelastic materials with different critical temperatures (Type A) and one consisting of a photoelastic material with and without aluminum powder (the powder added to alter the modulus of elasticity without changing the critical temperature (Type B)) are constructed by bonding two halves of the dissimilar materials together. Each type of specimen contains an artificial edge crack along the bond line and loaded normal to the bond line. After evaluating the two specimen types by measuring the variation of the Mode I stress intensity distribution through the specimen thickness, Type B was selected as a superior model and its features studied in detail.
Modeling and Simulation of Crack Initiation and Growth in Particulate Composites
Authors: Kwon Y. W. , Lee J. H. , Liu C. T. 
Published: July 2023

Abstract
A micro/macromechanical approach was used to model and simulate crack initiation and crack propagation in particulate composite structures. The approach used both the micromechanical and macromechanical analyses in tandem. The micromechanical analysis was based on a simplified micromechanical model and damage mechanics at the micro-level, and the macromechanical analysis utilized the finite element method. In using these methods, crack initiation and growth in a general shape of composite structure were investigated with an efficient computational effort. It was assumed that a crack initiates and/or propagates when localized damage is saturated. As a result, the crack length was assumed to be the size of the saturated damage zone. Matrix crack initiation and propagation at circular notch tips were simulated using this approach. Modeling and simulation were also conducted for cases of non-uniform particle distribution in particulate composite structures. Predicted results showed a good agreement with the experimental data.
The Computation of the Time Dependent Natural Convection Flow in a Horizontal Cylinder Heated From Below
Authors: Nagai Hiroaki , Emery A. F. 
Published: July 2023

Abstract
The time dependent natural convection in a horizontal cylinder heated from below is computed using the stream function/vorticity approach. The flow is characterized by a rapid development to a quasi-static state and then the occurrence of a periodic oscillation. The time of onset of the oscillations, their period, and their magnitudes are functions of the grid and time increments. It is found that a grid independent solution cannot be obtained by using finite differences and we speculate that this is true for other computational methods. If the grid is sufficiently fine and the time step is sufficiently small, fine and small being related to the Rayleigh number, it is possible to extrapolate to zero grid and time increments. The extrapolation is linear in time, but not in space.
Destruction of Hazardous Military Wastes Using Plasma Arc Technology
Authors: Kanaras Louis , Qazi Mahmood 
Published: July 2023

Abstract
A Plasma Arc Technology (PAT) system treats hazardous wastes in a furnace, at temperatures of 2000° C, or higher, using a plasma torch. The organic components vaporize, decompose or oxidize. The off-gases consist of hydrogen, carbon monoxide, carbon dioxide and nitric oxides. A wet air scrubber is used to remove most of these gases. The scrubber water is treated and recycled. Metal-bearing solids are melted or vaporized. The solids are usually recovered as molten metal, or as non-leachable vitrified slag, suitable for disposal in a landfill.
A Plasma Arc Centrifugal Treatment system was used to evaluate this technology for destruction of the four military hazardous wastes listed below:
1. Sludge from Longhorn Army Ammunition Plant, TX;
2. Blast media from Letterkenny Army Depot, PA;
3. Medical incineration ash from Aberdeen Proving Ground, MD; and
4. Contaminated soil from open burning/open detonation ground at Picatinny Arsenal, NJ.
The evaluation, Phase 1 of a two-phase program, includes determining the process capability of PAT for the ultimate destruction of hazardous components; verifying the suitability of the resulting slag for regular landfill disposal; identifying potential hazards associated with the process emissions; and developing qualified cost estimates for the future utilization of the process on large scale operations.
Process variables such as feed rate, composition of off-gases, run duration, percentage of oxygen used in the secondary chamber, and chamber temperature are controlled. Material balance, destruction and removal efficiency (DRE), air emission quality, wastewater quality, and suitability of slag for landfill are determined. The results from these test runs and analyses are presented in this paper.
In Phase 2, four new candidate waste streams were selected, and are listed below:
1. Waste paint from a U.S. Navy facility;
2. Garnet blast media from a U.S. Air Force Base;
3. Simulated oil-contaminated sorbent, used by Tri-Services and private industry; and
4. Mendocino soil spiked with surrogate chemical warfare materials.
Phase 2 testing begins in May 1996, and the results will be available in July 1996.
The ultimate success of PAT for destroying hazardous wastes depends on achieving a slag that is non-leachable and meets Resource Conservation and Recovery Act (RCRA) requirements, and off-gases and scrubber water that meet Clean Air and Clean Water Act standards.
Preliminary results of Phase 1 show that all slags passed Toxicity Characteristics Leaching Procedure (TCLP) tests, for land disposal requirements; air quality meets California standards, and scrubber water can be treated and recycled.
Application of the Three Phase AC Plasma Generator for Drug Destruction
Authors: Polovtsev Igor S. 
Published: July 2023

Abstract
Experiments for gas destruction with the help of the new three phase AC plasma generator were performed. Advantages of the new type plasma generator were studied. It was shown that this generator can be successfully used for destruction of hazardous wastes. Tests methane, freon and malathion were performed. Results of the tests show complete destruction of the injected gases.
Groundwater Removal Near Heat Dissipating Waste Packages
Authors: Manteufel Randall D. 
Published: July 2023

Abstract
The thermohydrologic environment of heat-dissipating nuclear waste packages in a subsurface repository is affected by ventilation of the facility prior to permanent closure. Heat dissipated by the waste will raise the temperature of host rock and vaporize groundwater. Ventilation will remove some heat and water vapor from the subsurface, creating a desiccated region surrounding the waste packages. The resulting hot, dry environment will tend to favorably extend the containment time of the waste. This work evaluates the transient temperature field near emplacement drifts and predicts the extent of rock dryout and removal of groundwater. For two hypothetical ventilation schemes with 30-yr-old fuel and repository loading of 40 metric tons of uranium (MTU) per acre, about 4 to 5 m of rock surrounding the drifts are predicted to be dried during the pre-closure period.
Destruction of Ammonia and Acetic Acid by Hydrothermal Oxidation
Authors: Lee Albert , Saulters Oral S. , Connon Corinne S. , Castillo Harlen G. 
Published: July 2023

Abstract
This investigation demonstrates that both ammonia and acetic acid, which are refractory intermediates in metabolic waste destruction by hydrothermal oxidation, are more effectively oxidized with hydrogen peroxide than oxygen at lower temperatures. Our results highlight the differences between the two oxidants and offer an explanation of the disparities presented in the literature regarding the similarities and dissimilarities of peroxide and oxygen in hydrothermal systems. Furthermore, evidence is presented that shows acetic acid and ammonia may be destroyed better in combination than separately.
Numerical Prediction of Low Frequency Combustion Instability in a Model Ramjet Combustor
Authors: Shang H. M. , Chen Y. S. , Shih M. S. , Farmer R. C. 
Published: July 2023

Abstract
A numerical analysis has been conducted for low-frequency combustion instability in a model ramjet combustor. The facility is two-dimensional, and is comprised of a long inlet duct, a dump combustor chamber, and an exhaust nozzle. The experiments observed that the combustor pressure oscillation under the particular operating condition did not have much cycle-to-cycle variation. The main resonant frequency occurs at about 65 Hz for this case. In the numerical analysis, a time accurate Computational Fluid Dynamics (CFD) code with a pressure-correction algorithm is used, and the combustion process was modeled with a single step chemistry model and a modified eddy breakup model. A high-order upwind scheme with flux limiter is used for convection terms. The convergence of the linear algebraic equations is accelerated through a preconditioned conjugate gradient matrix solver. The numerical predictions show that the flame oscillates in the combustion chamber at the calculation condition and are justified by the experimental schlieren photographs. The numerical analyses correctly predict the chamber pressure oscillation and the unstable combustion mode. However, the pressure oscillation frequency is over predicted compared with the experimental data. The discrepancy can be explained by the simplified turbulence and combustion model used in this study, and the uncertainty of the inlet boundary conditions.
Numerical Simulation of Spark Ignition and Flame Propagation
Authors: Bokka V. K. , Matthews R. D. , Ezekoye O. A. , Davis G. C. 
Published: July 2023

Abstract
A theoretical model to simulate spark ignition and subsequent flame propagation is presented. The model incorporates physical models of the breakdown process, which include effects of the blast wave generated during breakdown and chemical kinetics of fuel combustion. The energy and species equations are solved using a control volume method. A three step mechanism is used to simulate chemical kinetics for fuel combustion and nitrogen chemistry. Plasma ionization is included and its composition is calculated by assuming local thermal equilibrium using statistical thermodynamics and molecular theory. The effects of power input, spark energy, and mixture equivalence ratio on the kernel growth and flame propagation are obtained and compared with experimental and computational results available in the literature.
Improved Damping and Stiffness in Composite Structures Using Geometric Fiber Wave Patterns
Authors: Pratt William F. , Rotz Christopher A. , Jensen C. Greg 
Published: July 2023

Abstract
The use of continuous wave geometric patterns in carbon fiber reinforced plastics for improved structural damping is investigated. This method uses viscoelastic materials that are co-cured with and embedded between fiber layers having continuous wave-like patterns to improve both damping and stiffness in the structure. The result is a practical and more production worthy method of structural damping.