bluuebunny/crossref_metadata_2025_split huggingface dataset:
Transverse Vibration of Thin Rotating Disks: Nonlinear Modal Analysis
Authors: Hamidzadeh H. R. , Nepal N. , Dehghani M. 
Published: January 2022

Abstract
An analytical method is adopted to determine natural frequencies for a nonlinear spinning disk. The disk is assumed to be isotropic and rotating under steady state conditions. The effects of amplitude and rotating speed on natural frequencies are determined. The developed procedure is also capable of analyzing natural frequencies of linear free vibration, which is independent of amplitude. Attention is confined to determine natural frequencies for different number of nodal diameters. The developed procedure does not consider modes of vibration corresponding to nodal circles. Validity of this procedure is verified by comparing some of the computed results with those established for certain cases.
A Practical Approach for Impact Noise Prediction of Chain Drive Systems
Authors: Zheng H. , Xu Z. , Liu G. R. , Lam K. Y. , Wang Z. Z. , Ito T. , Takamori N. 
Published: January 2022

Abstract
This paper presents an analytical procedure for the noise level prediction of chain drive systems. The roller chain drive system for a motorcycle product is first modeled using finite element techniques and its operation under a typical operating condition is numerically simulated using a commercial software to obtain the acceleration response of each chain roller. An acoustical model relating the acceleration and its induced sound pressure is developed on the basis of the acoustic dipole field created by an oscillating rigid sphere. The acceleration time-histories of all rollers are thus used to predict the sound pressure level radiated by the roller chain drive under different driving conditions. The predicted time-history of sound pressure is further compared with available experimental results. It is shown that the prediction is in reasonable agreement with experimental measurements and the procedure works in an efficient manner for noise prediction of chain drive systems in a virtual acoustical design environment.
Numerical Modeling of Microwave Heating in Containerized Liquids
Authors: Zhang Qiong , Jackson T. H. , Ungan A. 
Published: January 2022

Abstract
This study reports on a three dimensional numerical model to simulate the convection of liquids in a rectangular single-mode microwave cavity. Three-dimensional Finite Difference Time Domain (FDTD) explicit method was employed to predict the electromagnetic field strengths and the absorbed power distributions both in the cavity and the liquid by solving transient Maxwell’s equations. Finite Control Volume method with the SIMPLER algorithm was used to obtain the temperature profiles and flow patterns by solving the unsteady Navier-Stokes equations and energy equations. The nonlinear coupling of the volumetric microwave heating source to the energy equation was handled through an iteration process. The results indicate the coupled phenomena of the microwave resonance, absorption of microwave energy, and convection driven flows. In order to illustrate the phenomena an example of microwave heating of containerized corn oil is provided.
Effect on Natural Convection of the Distance Between an Inclined Discretely Heated Plate and a Parallel Shroud Below
Authors: Manca Oronzio , Nardini Sergio , Naso Vincenzo 
Published: January 2022

Abstract
An experimental investigation into air natural convection on an inclined discretely heated plate with a parallel shroud below has been carried out. Three discrete strips were located in different positions on the heated wall. The distance between the walls, b, has been changed in the range 12.3–40.0 mm and two values of the heat flux dissipated by the heaters have been taken into account. Several inclination angles between the vertical and the horizontal have been tested. The wall temperature distribution as a function of the channel spacing and the inclination angle, the source heat flux, the number and the arrangement of the heat sources is presented. Dimensionless maximum wall temperatures are correlated to the process parameters. Flow visualized patterns of the air are also reported. Local Nusselt numbers are evaluated and correlated to the local Rayleigh numbers and the tilting angles. The analysis shows that for angles not greater than 85°, the greater b does not involve the smaller wall temperatures, whereas at greater tilting angles (&gt; 85°) there is an opposite tendence. These behaviors are confirmed by flow visualization at angles equal to 85° and 90° and b = 20.0 and 32.3 mm. The exponent of monomial correlations among local Nusselt and Rayleigh numbers are in the 0.23–0.26 range.
A Numerical Investigation of the Convective Heat Transfer in Unsteady Laminar Flow Past a Single and Tandem Pair of Square Cylinders in a Channel
Authors: Rosales Jorge L. , Ortega Alfonso , Humphrey Joseph A. C. 
Published: January 2022

Abstract
The unsteady laminar flow and heat transfer characteristics due to a square cylinder located in a channel with a fully-developed inlet velocity profile were studied numerically. The effects of an upstream eddy-promoting cylinder and the effects of the proximity of the cylinder to the channel wall were examined at a fixed cylinder Reynolds number of 500 and Prandtl number of 0.7. The local time-averaged Nusselt number for each face and the time-averaged cylinder Nusselt number were determined, as well as aerodynamic characteristics such as cylinder lift, drag, and eddy-shedding Strouhal number. The results show that the cylinder Nusselt number decreases for both the single and the tandem pair of cylinders as they approach the channel wall. This is primarily due to the reduced mean velocity near the wall. The front face of the cylinder consistently displays the highest Nusselt number. The time-mean drag coefficient decreases for both the single and the tandem cylinders as the wall is approached. The presence of the upstream eddy-promoting cylinder significantly reduces the drag of the downstream cylinder compared to that of the single cylinder but has little effect on the cylinder lift. However, the cylinder overall Nusselt number also decreases, in contrast to previous studies in uniform flow. The eddy shedding Strouhal number increases slightly as the wall is approached and is much larger for the tandem pair than for the single cylinder case for all positions. The amplitude of eddy shedding induced oscillations is significantly dampened as the cylinder approaches the channel wall.
On the Relationship Between Heat Transfer and Drag Reductions for Polymer and Surfactant Solutions
Authors: Aguilar G. , Gasljevic K. , Matthys E. F. 
Published: January 2022

Abstract
Drag-reducing solutions exhibit simultaneous friction and heat transfer reductions, yet it has been widely believed that there is a decoupling between the two effects, an unexplained and puzzling concept. In this work, we have conducted a dedicated study to reexamine this issue, using a wide range of flow conditions from onset to asymptotic, pipe diameters, and various fluids ranging from polymer to surfactant solutions. All our data and those of some other investigators were found to be remarkably well correlated by a constant ratio between the heat transfer and drag reductions over the entire range of conditions examined. In addition, this ratio was found to hold even at and near the onset of drag reduction phenomenon, and also upon departure from the asymptotic regime. We have also shown that the onsets for drag and heat transfer reductions are the same, and that degradation or dilution result in simultaneous departure from asymptotic conditions. All these results support the concept that heat transfer and drag are indeed strongly coupled under all conditions investigated. This information should provide new insight into the fundamental mechanisms underlying the relationship between the drag and heat transfer reduction phenomena. In addition, the practical engineering impact of this finding is very significant in that it allows us now to predict directly the heat transfer from friction measurements or vice-versa, for these fluids.
Effect of Jet Location on Impingement Cooling of a Rotating Disk
Authors: Saniei Nader , Yan Xiaojun 
Published: January 2022

Abstract
Heat transfer results are presented for a rotating disk cooled with an impinging air jet directed on its free surface. In this study, local heat transfer distribution was investigated for a disk under the combination of rotation and jet impingement. The main focus considered here was cooling by pure rotation and the effect of location of the jet center relative to the disk center. Several important factors, such as rotational Reynolds numbers, jet Reynolds numbers, and jet-to-disk spacing were considered when the jet was positioned in different distances from the center of the disk. Disk rotational speed was varied from 250 to 4,000 rpm while three jet Reynolds numbers of 6,800, 24,000, and 48,000 were used. The jet was placed perpendicular to the disk surface at four different distances from the center of the disk. These distances were, zero cm (center-to-center), 3.5 cm, 6.9 cm and 8.9 cm. The jet-to-disk diameter ratio was about 0.09. This ratio was kept constant for this study.
The heat transfer measuring technique for this study was a transient technique which employed liquid crystals. A near uniform wall temperature thermal boundary condition was achieved for the disk by constructing an enclosed insulated oven with well-controlled heating elements and a sliding door on the top for easy access. The results of this investigation reveal that, in most cases for rotating disk with jet impingement cooling, local heat transfer distribution follows a parabolic function which has a minimum at a radial distance (from the disk center) of about one half of the disk radius.
Heat Transfer in Vertically Vibrated Granular Materials
Authors: Wassgren Carl R. , Beasley Donald E. , DeWachter Ryan N. 
Published: January 2022

Abstract
In order to enhance heat transfer from a heated surface to a granular material, the surface is sometimes subject to vibration with the expectation that the oscillations will promote material renewal at the surface and result in increased heat transfer to the bed. Indeed, previous studies have shown that depending on the vibration parameters and bed depth, the bed of material will exhibit a variety of dynamic phenomena including side wall convection cells, surface waves, and kink waves; all of which influence the motion of particles within the bed. This paper investigates the time-averaged heat transfer coefficient from a vertically-vibrated, heated plate to a deep bed of granular material over a range of oscillation parameters. An experimental apparatus was designed consisting of a narrow plexiglass container with a heated copper base embedded in a Delrin jacket. The container was partially filled with soda lime glass spheres and mounted on an electromagnetic shaker which provided the vertical, sinusoidal oscillations with controllable amplitude and frequency. The resulting heat transfer coefficient measurements are presented as a function of the oscillation parameters for oscillation frequencies between 15–60 Hz and oscillation acceleration amplitudes between 0 and approximately 7.0g where g is the acceleration due to gravity. The steady state heat transfer coefficient is found to increase over 300% for an acceleration amplitude between one and two g.
Computational Aspects of the Sectional Modeling Method for Predicting Spray Combustion
Authors: Greenberg J. Barry , Kalma Avinoam 
Published: January 2022

Abstract
In this paper we discuss computational aspects of using the sectional modeling method for calculating combusting sprays. We consider a model problem concerning the propagation of a spherical laminar flame into a mixture of air, fuel vapor and a polydisperse spray of fuel droplets. A detailed description is given of (i) a new numerical treatment of the spray equations for sectional mass and momentum conservation using an implicit scheme and a certain ordering that takes advantage of their special structure, and (ii) a scheme in which the chemical reaction source terms are computed implicitly, thus enabling larger time steps to be used without loss of stability. As an example of the application of the proposed method sample results are presented for the case in which the chemistry is modeled using a global scheme, and for which the droplets are permitted to be in dynamic disequilibrium with their surroundings. These new results (i) demonstrate the efficacy of the numerical procedure, (ii) provide evidence that for a qualitative understanding of spray combustion in the current context it is sufficient to neglect the velocity differences between the gas and liquid phases, and (iii) show that for a quantitative understanding these velocity differences must be accounted for.
Modeling of Thermal Performance of a Porous Radiant Burner
Authors: Fu X. , Viskanta R. , Gore J. P. 
Published: January 2022

Abstract
A one-dimensional model accounting for the interaction of convection, conduction, radiation and chemical reaction in a porous radiant burner/healer has been developed to predict the thermal performance of the natural gas burner. The porous radiant burner consists of two layers of cellular (reticulated) ceramics of different porosity and mechanical structure. The chemical heat release was simulated using a uniform heat source model to avoid the uncertainties associated with chemical kinetics parameters in a reduced chemical mechanism under strongly non-adiabatic conditions. Radiative transfer in the porous medium is modeled using the two-flux approximation. The model predictions reveal quantitatively conjugate heat transfer between convection, conduction, radiation and chemical heat release. A study of the effects of various parameters on the thermal performance of the porous radiant burner and comparison of predictions with experimental data are reported. The results obtained show that the flame thickness in this type of burners is much broader than that of conventional adiabatic combustion due to the strong conduction and radiation feedback from the high temperature (flame) region to the preheat region. The peak gas temperature is lower than that for conventional adiabatic premixed combustion conditions since part of the chemical heat release is convected to the solid.
A Computational Model for Enclosure Fires Incorporating Pyrolysis of Cellulosic Fuel
Authors: Yuen R. , de Vahl Davis G. , Leonardi E. , Yeoh G. H. , Chandrasekaran V. 
Published: January 2022

Abstract
Flame spread and fire over cellulosic materials occur when the burning region supplies sufficient heat to the virgin solid to cause gasification. Under proper conditions, the reaction between the generated volatiles and the oxidant (air) may be sustained. The characteristics of the flame spread are therefore the result of heat and mass transfer processes as well as finite-rate gas phase chemical kinetics.
We describe here a new three-dimensional mathematical model to study flame spread over cellulosic fuels. Both the pyrolysis and burning of a vertical timber wall of a room and the turbulent flow, combustion and radiation in the room, are included. The predictions of this model have been compared with the results of an experiment. Excellent agreement has been achieved.
A Numerical Investigation of the Scaled-up Effects on Flow, Heat Transfer, and Kinetics Processes of FCC Units
Authors: Chang S. L. , Zhou C. Q. , Lottes S. A. , Golchert B. , Petrick M. 
Published: January 2022

Abstract
Fluid Catalytic Cracking (FCC) technology is the most important process used by the refinery industry to convert crude oil to valuable lighter products such as gasoline. Process development is generally very time consuming especially when a small pilot unit is being scaled-up to a large commercial unit because of the lack of information to aide in the design of scaled-up units. Such information can now be obtained by analysis based on the pilot scale measurements and computer simulation that includes controlling physics of the FCC system. A Computational fluid dynamic (CFD) code, ICRKFLO, has been developed at Argonne National Laboratory (ANL) and has been successfully applied to the simulation of catalytic petroleum cracking risers. It employs hybrid hydrodynamic-chemical kinetic coupling techniques, enabling the analysis of an FCC unit with complex chemical reaction sets containing tens or hundreds of subspecies. The code has been continuously validated based on pilot-scale experimental data. It is now being used to investigate the effects of scaled-up FCC units. Among FCC operating conditions, the feed injection conditions are found to have a strong impact on the product yields of scaled-up FCC units. The feed injection conditions appear to affect flow and heat transfer patterns and the interaction of hydrodynamics and cracking kinetics causes the product yields to change accordingly.
Far-Infrared Transmittance and Reflectance of YBa2Cu3O7-δ Films on Si Substrates
Authors: Kumar A. Ravi , Zhang Zhuomin M. , Boychev Vladimir A. , Tanner David B. , Vale Leila R. , Rudman David A. 
Published: January 2022

Abstract
The transmittance and reflectance of superconductive YBa2Cu3O7-δ (YBCO) thin films deposited on Si substrates have been measured in the far-infrared frequency region from 10 to 100 cm−1 (wavelength from 1000 to 100 μm) at temperatures between 10 and 300 K. The effects of interference, optical resonance, and antireflection on the radiative properties of high-temperature superconducting (HTSC) films are observed and quantitatively analyzed. Furthermore, we have measured the reflectance of the HTSC film-substrate composites for radiation incident on the substrate side (backside reflectance) for the first time. The backside reflectance increases significantly from the normal state to the superconducting state at certain frequencies; this experimentally demonstrates that HTSC films can be used to build far-infrared intensity modulators. The complex refractive index of the YBCO films is determined from the measured transmittance using the Drude model in the normal state and a two-fluid model in the superconducting state. The complex refractive index obtained from this study is useful for various applications of YBCO films, including radiation modulators, detectors, and Fabry-Perot resonators.
Radiative Heat Transfer in Periodic Geometries Using a Finite Volume Scheme
Authors: Mathur S. R. , Murthy J. Y. 
Published: January 2022

Abstract
A procedure for computing radiative heat transfer in translationally and rotationally periodic geometries is presented. The finite volume scheme is applied to meshes composed of arbitrary polyhedral control volumes. The angular domain is discretized into a finite number of control angles over which radiant energy is conserved. At periodic boundaries, control angle overhang occurs because of the misalignment of the arbitrary periodic face with the global angular discretization and due to the arbitrary rotation of adjacent modules with respect to each other. A discretization scheme using control angle pixelation is developed to conservatively transfer radiant energy between adjacent modules. The method is tested against analytical solutions and shown to perform satisfactorily.
Class-Room Experiences and Impact Evaluation of the Educational Software Heat Transfer 1.0 in a Heat Conduction Course
Authors: Maliska Clovis R. , Filgueiras dos Reis Marcus V. , Dihlmann Axel 
Published: January 2022

Abstract
This paper reports the first classroom experience using the package Heat Transfer 1.0 (Maliska et al, 1997) in an introductory heat conduction course. The key objective in conceiving Heat Transfer 1.0 was to stimulate the physical reasoning in heat transfer, bringing to the students the possibility of having intimacy with the flow of heat in physical situations where this flow is more complex than the usual 1D patterns presented in normal textbooks. Therefore, the basic idea behind its conceptual form was to have more than merely a tool to help the student to solve the heat conduction equation. The key objective was to create a tool that allows students to formulate new problems and to speculate about its physical behavior. More, the software should appear attractive and easy-to-use, becoming part of the students toolbox, and not seen as “one more package” whose use is compulsory in the course. Student’s opinions taken through a questionnaire submitted to them just after the end of the course revealed that they found the software easy-to-use and that it broadened their knowledge of conduction heat transfer.
An Analytical Study of Turbine Disks Incorporating Radially Rotating Heat Pipes
Authors: Cao Yiding , Chang Won S. , MacArthur Charles D. 
Published: January 2022

Abstract
In modern aero-engines, a turbine disk is normally cooled by compressed air bled from the engine compressor. A literature survey regarding the turbine disk cooling reveals that although the average air-cooling heat transfer coefficient is generally high, the local heat-transfer coefficient at the disk rim is low. Impinging jet cooling could be used to enhance the heat transfer at the rim, but its implementation is costly. One of the major causes of the high temperature at the rim is the low thermal conductivity associated with the turbine disk material. Based on this understanding, a turbine disk that incorporates radially rotating heat pipes has been introduced. The incorporation of the heat pipe would significantly increase the effective thermal conductance of the disk and spread the heat from the disk rim to a much large surface area, A unique disk design that employs interconnected heat pipe branches is also described for the purpose of cost reduction. To evaluate the effectiveness of the new turbine disk, a simplified analysis based on the one-dimensional and steady-state assumptions is made. The analytical results indicate that a disk that incorporates the heat pipe could reduce the disk rim temperature by more than 300°C, with only a moderate increase in the disk bore temperature. A turbine disk that employs rotating heat pipes is very effective for the disk rim temperature reduction. It also represents a new approach for cooling turbine rotor blades, and could find important applications in advanced gas turbines working at very high inlet temperatures.
A Frozen Startup Limit for Room Temperature Heat Pipes
Authors: Allred R. S. , Ochterbeck J. M. 
Published: January 2022

Abstract
The frozen startup performance of two room temperature heat pipes (one copper/water and one stainless-steel/biphenyl) was investigated. Biphenyl was selected as the second fluid due to its above ambient melting temperature of 69°C. The effects of steady-state input power, restart power, and non-condensable gas (NCG) charging on startup were examined. Also, the effects of the evaporator/ condenser length ratio were examined using the stainless-steel/biphenyl heat pipe. The presence of a non-condensable gas charge was found to have a more pronounced effect on startup characteristics than restart power or geometry. For cases typically of greater evaporator length to condenser length, the presence of NCG was not required to restart a room temperature heat pipe from the frozen state. All other cases were found to require NCG charging to successfully restart. Additionally, a previous analytical frozen startup limit developed for liquid metal heat pipes was modified for room temperature heat pipes to predict startup success/failure. It was shown that the newly developed frozen startup limit can successfully predict the startup performance of room temperature heat pipes.