bluuebunny/crossref_metadata_2025_split huggingface dataset:
Periodic Temperature Field and its Application to Thermophysical Property Measurement
Authors: Haji-Sheikh A. , Hong Y. S. , You S. M. , Beck J. V. 
Published: July 2023

Abstract
The frequency domain provides an interesting alternative platform for measuring thermophysical properties. The resulting measurement technique produces reasonably accurate thermophysical data from imprecise surface information. Having a periodic heat flux input at one surface, the thermal diffusivity is obtainable if temperature produces a measurable periodic effect at another surface. The analysis shows that only the phase shift is necessary to produce needed information while the boundary conditions can affect the experimental results. The feasibility of implementing this method is tested near room temperature using two different materials: Delrin and 304 stainless steel. The experiments yield accurate thermal conductivity and thermal diffusivity data for both materials but the data for Delrin exhibit smaller errors. Before performing experiments, a sensitivity analysis is carried out to determine the best range of frequencies for an experimental investigation.
Numerical Algorithms for Parameter Estimation
Authors: Zhuang Xinglai , Zhu Jianping 
Published: July 2023

Abstract
In this paper, we will discuss a numerical algorithm for estimating the unknown thermal conductivity coefficient in the heat equation using the temperature measurement at some points inside the domain. The algorithm has the following features:
• Efficient calculation of sensitivity coefficients. With the perturbation method discussed in this paper, the sensitivity coefficients can be calculated efficiently without repeated simulations or solving the adjoint equation.
• Accurate treatment of the measurements at different time steps. We have developed a method to consider the effect of measurements at all time steps more accurately.
• Adaptive regularization process. Instead of using a fixed constant as the regularization coefficient, we have developed a strategy to modify the regularization parameter dynamically during the solution process.
Numerical results will also be discussed in the paper to demonstrate the implementation of the algorithm and improvement in accuracy.
Local and Instantaneous Heat Transfer Characteristics of Arrays of Pulsating Jets
Authors: Sheriff H. S. , Zumbrunnen D. A. 
Published: July 2023

Abstract
Recent investigations of impinging jets have revealed that pulsations in the incident flow can be an effective technique for modifying convective heat transfer characteristics. While these studies focused on single impinging jets, industrial applications of impinging jets usually involve arrays of jets. When so configured, inter-jet interaction becomes a major consideration in achieving uniform and high heat transfer. To explore the effects of flow pulsations on the heat transfer performance of jet arrays, an experimental investigation has been performed of instantaneous and time-averaged convective heat transfer to a square, in-line array of circular air jets. The flow pulsation frequency was varied from 10 Hz to 65 Hz which corresponded to Strouhal numbers based on the nozzle diameter and velocity from 0.004 to 0.028. The pulse magnitude, which was defined as the ratio of the root mean square of the pulsating component of flow velocity to the mean flow velocity, was varied from 10% to 60%. Dual sensor hot film anemometry was used to document the jet flow-field. Instantaneous and time-averaged convective heat transfer was documented using a heat flux microsensor. An ensemble averaging technique was used to separate the pulsating component of flow velocity from the turbulent component and thereby assess the effect of flow pulsation on turbulence intensity. Instantaneous and time-averaged convective heat transfer conditions are documented as a function of pulse magnitude and pulse frequency within an unit cell of the array.
Heat Transfer From an Obliquely Impinging Circular Air Jet to a Flat Plate
Authors: Yan Xiaojun , Saniei Nader 
Published: July 2023

Abstract
A series of experiments was conducted for the measurement of local convective heat transfer coefficients for an obliquely impinging circular air jet to a flat plate. In the experiments, the oblique angles selected were 90°, 75°, 60° and 45° with 90° being a vertical jet. Two different Reynolds numbers of 10,000 and 23,000 were considered for the purpose of comparison with previous data available in the literature. Another parameter varied in the measurements was the dimensionless jet-to-plate distance, L/D. Four values of L/D(2, 4, 7 and 10) were considered in the experiments.
The experiments were conducted using the pre-heated-wall transient liquid crystal technique. Liquid crystal color changes were recorded with a video system. Local convective heat transfer coefficients were obtained through the surface transient temperatures which were related to the recorded color information.
Detailed local heat transfer coefficients were presented and discussed in relation to the asymmetric wall jet upon impingement of the jet flow. Results of experiments show that, for a given flow situation the point of maximum heat transfer shifts away from the geometrical impingement point toward the compression side of the wall jet on the axis of symmetry. The shift is more pronounced with a smaller oblique angle (larger jet inclination) and a smaller jet-to-plate distance. Comparisons of experimental results with existing heat transfer data for both obliquely impinging jets and vertical impinging jets are made. The effect of oblique angles on heat transfer was assessed.
Capacitance Probes for Measurement of Liquid Film Thickness
Authors: Chen X. , Butler T. , Brill J. P. 
Published: July 2023

Abstract
Liquid film thickness measurement is very important in multiphase science and technology. A capacitance probe is presented in this paper, including its basic principle, geometrical design, electronic circuit, and experimental tests in measuring film thickness during gas-liquid two-phase flow. This method is based on the difference between the dielectric constants of the gas and liquid phases. A ratio-arm bridge circuit is used to convert the capacitance of the fluids between twin parallel plates into voltage. The voltage output from the capacitance probe exhibits an excellent linear relationship with the liquid film thickness. Experiments have shown that the parallel-probe capacitance method is very suitable to gas-hydrocarbon liquid system.
An Experimental Study of Gas-Liquid Slug Flow in Vertical and Inclined Tubes Using High Speed Motion Analyzer
Authors: Xia Guodong , Zhou Fangde , Hu Mingsheng 
Published: July 2023

Abstract
Experimental investigation was carried out for gas-liquid slug flow in vertical and inclined tubes. The non-invasive measurements of the gas-liquid slug flow were taken by using the EKTAPRO 1000 High Speed Motion Analyzer. The present paper has obtained the information on the velocity of the Taylor bubble, the size distribution of the dispersed bubbles in the liquid slugs and some characteritics of the liquid film around the Taylor bubble. The experimental results are in good agreement with the available data.
Boiling and Condensation Heat Transfer Correlations for Refrigerant-Oil Mixture Flows Inside Augmented Tubes
Authors: Usmani G. I. , Ravigururajan T. S. 
Published: July 2023

Abstract
General correlations to predict boiling and condensation heat-transfer-coefficient are proposed. Data analyzed include 134a condensation and evaporation of refrigerants such as R-22, R-12, R-113, and R-134a. Wide ranges of mass flux, heat flux, pressure, and vapor velocities are covered. Both low-fin tubes and the micro-fin tubes are considered. For boiling correlation more than 975 data points from four experimental studies are correlated and for condensation more than 525 data points from three experimental studies are correlated. The efforts resulted in the development of simple correlations for predicting the heat-transfer-coefficients during condensation and evaporation inside augmented tubes.
The results show that the boiling heat-transfer-coefficients decreased with increasing oil concentration and vapor quality, and increased with tube enhancement severity factor. Increasing mass flux, however, diminished the adverse effect of oil on the heat-transfer-coefficient. During condensation, the presence of oil diminished the heat-transfer performance of a micro-fin tube. The heat-transfer-coefficient decreased with increasing oil concentration used, and also with increasing severity factor.
A Fluid Dynamics Study of a Circulating Fluidized Bed With Secondary Air Injection
Authors: Pécora Araí A. B. , Goldstein Leonardo 
Published: July 2023

Abstract
This paper presents an experimental study on the fluid dynamics of a circulating fluidized bed with secondary air injection. The experiments were run in a 4 m high, 100 mm internal diameter riser system. The solid material was 200–920 μm diameter sand. The gas temperature at the beginning of the riser was around 200°C and the superficial gas velocity varied in the 2.5–9.5 m/s range. The data obtained made possible to suggest correlations for the pressure drop in a cyclone and in a recirculating L-valve, which are necessary to study the system pressure balance. The pressure profiles in the loop of the circulating fluidized system show the secondary air injection influence.
Overall and Average Local Heat Transfer From a Horizontal Cylinder in a Gas-Fluidized Bed With an Opposing Oscillatory Flow
Authors: Pence Deborah V. , Beasley Donald E. 
Published: July 2023

Abstract
The Pulsed Atmospheric Fluidized Bed Combustor (PAFBC), a hybrid combustor concept that couples a pulsed combustor with an atmospheric bubbling fluidized bed, has technical advantages in energy efficiency and emissions. The present study examines fundamental aspects of heat transfer in this hybrid combustor by measuring the effect of an opposing oscillatory flow on the overall and time-averaged local heat transfer in a laboratory scale bubbling gas-fluidized bed. This opposing secondary flow consisted of a steady mean component and an oscillating component thereby modeling the flow in the tailpipe of a pulsed combustor.
Data were acquired for a monodisperse distribution of particles with a mean diameter of 345 μm and total fluidization ratios ranging from 1.1 through 2.7. Overall and time-averaged local heat flux measurements from the surface of a submerged horizontal cylinder show that heat transfer characteristics are significantly altered by an opposing oscillatory flow. Increases in overall heat transfer on the order of 12% were identified for operating conditions with low primary’ and secondary flow rates and low pulse frequencies. These enhancements were identified to be a consequence of significant localized enhancements. The fundamental trends and magnitude of the particle Nusselt number are effectively characterized by a modified form of the Strouhal number.
Interfacial Shear Modelling in Two-Phase Annular Flow
Authors: Kumar Ranganathan , Edwards David P. 
Published: July 2023

Abstract
A new interfacial shear stress model called the law of the interface model, based on the law of the wall approach in turbulent flows, has been developed and locally applied in a fully developed, adiabatic, two-phase annular flow in a duct. Numerical results have been obtained using this model in conjunction with other models available in the literature that are required for the closure of the continuity and momentum equations. These results have been compared with droplet velocity data (using laser Doppler velocimetry and hot film anemometry), void fraction data (using gamma densitometry) and pressure drop data obtained in a R-134A refrigerant test facility. Droplet velocity results match the experimental data well, however, the prediction of the void fraction is less accurate. The poor prediction of void fraction, especially for the low void fraction cases, appears to be due to the lack of a good mechanistic model for entrainment.
Temperature Measurements via Narrow Line Laser Absorption of Carbon Dioxide
Authors: Wooldridge Margaret S. 
Published: July 2023

Abstract
Theoretical development for temperature measurements via narrow line, infrared absorption of carbon dioxide (CO2) is presented. The proposed technique is based on rapid-scanning of two adjacent absorption line shapes. Spectroscopic considerations for sensitivity to temperature measurements are discussed. Several line pairs are evaluated, and the R(58) and R(60) transitions of the (00°1) ← (00°0) band are suggested for use in high temperature measurements for combustion systems.
The Effect of Specimen Geometry on Fatigue Crack Growth Behavior in Metal Matrix Composite
Authors: Sallam H. E. M. , Nayeb-Hashemi H. 
Published: July 2023

Abstract
An elastic-plastic two-dimensional finite element model was utilized to simulate the effect of the specimen geometry, i.e. type of specimen and the presence of the notch, on the crack tip deformation, CTD, and stresses and strains distributions around the crack tip in both the plane stress and the plane strain conditions. It was found that, the values of T-stresses and strains near the crack tip were significantly affected by the specimen type and the presence of the notch in both plane stress and plane strain conditions, i.e. thin and thick specimens. However, the analyses show that the presence of notch has a little effect on plastic zone size and shape and crack tip opening displacement, CTOD. The present results were employed to explain the main parameters controlling the fatigue crack growth, FCG, behavior in metal matrix composites, MMCs.
Recent Advances in Finite Element Method for Stochastic Structures
Authors: Elishakoff Isaac , Ren Yongjian 
Published: July 2023

Abstract
Extensive motivation to do an additional work in the finite element method in stochastic problems (FEMSP) is discussed. The qualitative comparison of FEMSP with the state of the art of the deterministic FEM is given. These observations and thoughts are then realized in several manners. We first present the exact inverse FEMSP, which however can not serve as a general tool for stochastic analysis of complex structures. The new variational principles for stochastic beams, for the mean response function, as well as response’s auto-correlation function are formulated and the FEM based on the variational principles is presented. Finally, a general non-perturbative FEM for stochastic probelms is developed, based on the element-level flexibility. It is concluded that much work needs to be done in order FEMSP to be at the level compared to that of the deterministic FEM. The advantage of the main methods presented here over the conventional ones lies in their non-perturbaxional nature. Numerical examples are presented.
Natural Convection Within a Horizontal Circular Cylinder
Authors: Chopin Therese R. 
Published: July 2023

Abstract
Natural convection is modeled in an infinitely long horizontal circular cylinder which is heated from below and cooled from above. This combination of thermal boundary conditions produces an unstable flow which must be modeled with a transient algorithm. The buoyancy-driven flow is studied for three different values of the Rayleigh number, Ra = 5(103), 5(104), and 5(105). The problem is modeled and solved using the finite element based code ANSYS/FLOTRAN™ computational fluid dynamics (CFD) program. Results include temperature and streamline contours.
A Generalized Model for Determining the Thermal Response to a Nuclear Waste Repository
Authors: Jendoubi S. , Kulacki F. A. 
Published: July 2023

Abstract
A generalized integral method for determining unsteady, one-dimensional heat conduction in multi-layer systems with arbitrary thermophysical properties has been developed. Temperature distributions within each sublayer are represented with approximating polynomials, and the source of heat can exist at any location in the system. The recurrence relations between coefficients of temperature profiles are generalized so that any number of sublayers can be handled. Although the model is a general one, it has been applied to temperature independent thermal properties in this study to illustrate the efficiency of the computations. The model is exercised for the stratigraphy of the proposed National High Level Nuclear Waste Repository at Yucca Mountain, Nevada. Results indicate that the model provides a powerful tool for both bounding the coupled thermal and hydrologic performance of the repository and assessing thermal uncertainties over both short and long time scales of repository operations.
The Complex Structure of Propagating Spray Flames
Authors: Kalma A. , Greenberg J. B. 
Published: July 2023

Abstract
The time evolution of a propagating laminar planar pre-mixed multisize spray flame has been investigated numerically. Special attention was focused on the influence of the spray multisizedness (polydispersity) on the structure of the resulting flame. For sprays having identical initial Sauter mean diameters, but different size distributions, both the flame structure and its propagation rate can be significantly altered. The ramifications of flame sensitivity to the spray’s characteristics on modeling and possible control of toxic emissions is discussed.
Thermal Oxidation of Chloro-Hydrocarbon Materials: Prediction and Measurement
Authors: Smith J. D. , Cope R. F. , Van Dell R. D. 
Published: July 2023

Abstract
Efficient thermal oxidation (&gt; 99.99% conversion) utilizes high temperatures associated with “simple” diffusion flames to convert chloro-hydrocarbons (RCls) into H2O, CO2, and HCl. To optimize this process, it is necessary to understand the physical phenomena occurring inside the diffusion flame. This understanding is culminated in advanced combustion models. Although these models may help identify important factors, a more balanced research approach has been used to support industrial thermal oxidation units. Besides modeling, fundamental laboratory experiments coupled with full-scale plant experiments are also essential. Laboratory measurements focus on specific phenomena while plant experiments include the coupled effects of all of the governing subprocesses. This balanced approach leads to a better understanding of thermal oxidation which leads to more efficient operation.
Air Staging and Swirl-Assisted Mixing and Combustion of Methane and Air
Authors: Krass Brady J. , Puri Ishwar K. 
Published: July 2023

Abstract
Two-stage combustors offer an effective method for the suppression of combustion-generated pollutants. The imposition of swirl on the fuel and/or oxidizer flows causes recirculation which enhances mixing that in turn reduces NOx (i.e., total nitrogen oxide) formation. We investigate the characteristics of a burner that allows for both good mixing through swirl, and staging. Temperature measurements establish the presence of separate rich and lean zones during staging. Relative uniformity of the temperature profiles, and small magnitudes of temperature fluctuations are characteristic of the burner exit. In the burner product can be either dispersed (with no radial swirl-type structure) or concentrated into separate lean and rich regions. High speed video images confirm the swirling of the inner rich flame. The swirl allows interaction of the primary region with the secondary zone, and shears the secondary fuel jets causing further turbulence and vorticity that enhances mixing and prevents hot spots. Under conditions favoring unmixedness, product distribution occurs on relatively thin flamelet sheets that curve and wrinkle due to vorticity. In general, lower fractions of secondary air are beneficial from the perspective of mixing and homogeneity. The emission index of NOx, i.e., EINOx values correlate with the relative fractions of primary air. Fluid dynamical effects supersede those related to stoichiometry in the burner. The maximum EINOx value is lower than typical EINOx values for jet-type nonpremixed flames. Therefore, we conclude that we have successfully designed and characterized a low-NOx burner.
An Investigation of Methane-Air Nonpremixed Combustion in a Rapid-Mixing Burner
Authors: Bunnell Russell K. , Krass Brady J. , Puri Ishwar K. 
Published: July 2023

Abstract
An experimental analysis was performed on a rapid-mixing burner in which the mixing of methane and air occurs in discrete vortex structures prior to burning. Air is distributed by large vortex structures, and burning of fuel-air are mixtures occurs in smaller eddies. The burner design was evaluated by utilizing various visualization and diagnostic techniques. The advantages and disadvantages of each are discussed. High speed video is employed to evaluate fickering phenomena. Mixing induced by vortex structures is visualized by means of scattering across a laser light sheet. Velocity measurements made with a laser Doppler velocimeter confirm flow divergence and high kinetic energy at the flow edges through which the vortex structures transit. Temperature measurements made with a fast response thermocouple reveal a well-mixed combustion zone. The flame flickers in a manner similar to that occuring in isothermal helium plumes. Therefore, the results present sufficient evidence that a rapid-mixing burner has been successfully devised using radial fuel injection and a noncircular duct cross-section.
Four-Component Numerical Simulation Model of Radiative Convective Interactions in Large-Scale Oxygen-Hydrogen Turbulent Fire Balls
Authors: Surzhikov Sergey T. 
Published: July 2023

Abstract
Two-dimensional radiative gas dynamics model for numerical simulation of oxygen-hydrogen fire ball which may be generated by an explosion of a launch vehicle with cryogenic (LO2-LH2) fuel components is presented.
The following physical-chemical processes are taken into account in the numerical model:
- an effective chemical reaction between the gaseous components (O2-H2) of the propellant,
- turbulent mixing and diffusion of the components,
- radiative heat transfer.
The results of numerical investigations of the following problems are presented:
- the influence of radiative heat transfer on fire ball gas dynamics during the first 13 sec after explosion,
- the effect of the fuel gaseous components afterburning on fire ball gas dynamics,
- the effect of turbulence on fire ball gas dynamics (in a framework of algebraic model of turbulent mixing).
Benchmark Problem: Natural Convection Within a Horizontal Circular Cylinder
Authors: Huang H.-W. , Heinrich J. C. 
Published: July 2023

Abstract
Two-dimensional buoyancy-driven flow inside a horizontal circular cylinder is modeled using the finite element method. Incompressibility is imposed via the penalty function approximation and convective stability is maintained through the use of a Petrov-Galerkin method. Results are presented for Rayleigh numbers 5 × 103 ≤ Ra ≤ 5 × 107 and unit Prandtl number.
Effect of Controlled Material Variations on the Farfield Sound Radiation From Composite Beams
Authors: Slaughter Julie C. , Mann J. Adin , Adams Dan O. 
Published: July 2023

Abstract
The effects of the geometry and material make-up of a patch embedded in a carbon/epoxy beam were investigated. A tapered carbon/epoxy patch and a square-edged carbon/epoxy patch were each embedded in beams. Patches of Syncore (a syntactic foam core) and Syncore embedded with pultruded carbon rods were also embedded in beams. The radiated sound power per unit length was computed from the measured surface vibration of the beams. A model based on Hamilton’s Principle was used to generate data for comparison with the experimental data. Results from the model are promising but more development is needed.