bluuebunny/crossref_metadata_2025 huggingface dataset:
A Study of Chemical Reactivity in Ceramic Heat Exchangers
Authors: Day J. P.
Published: November 2010

Past techniques to evaluate the resistance to chemical attack of rotary ceramic regenerator structures and materials have been used as screening tests with some success. The major drawback, though, has been the lack of simulation of the thermal and chemical characteristics of the exhaust stream. A new technique has been developed which allows one to reproduce more closely the environment of the regenerator and therefore determine the response of structures and materials to various chemical species and thermal gradients. Sulfur attack results from this test are compared with those from previous laboratory tests and also gas turbine engine tests. Materials considered include both β-spodumene and cordierite compositions. The essential conclusions from this study are: 1 – The SO2-gradient furnace can simulate the chemical and thermal environments of a rotary regenerator in operation; 2 – Sulfuric acid vapor ion-exchange is the predominant sulfur related reaction in β-spodumene rotary regenerators; 3 – Leaching of cordierite regenerators by sulfuric acid will not be observed unless the temperature on the cold face of the regenerator lies below the sulfuric acid dew point of the combustion gases.
Sustained Fast Valving Applied to Tennessee Valley Authority’s Watts Bar Nuclear Units
Authors: Martin H. F. , Tapper D. N. , Alston T. M. , Edwards L. E. , Thomas R. J. , McCuiston B. E. , Finney J. I. , Park R. H.
Published: November 2010

The first application of sustained fast valving for nuclear units is planned for units 1 and 2 at the Tenneseee Valley Authority’s (TVA) Watts Bar Nuclear Plant. The proposed turbine cycle and the advantages of sustained fast valving to the power system are presented. The turbine cycle simulation is discussed and the effects of feedwater heater energy storage on short term power transients are demonstrated. The mechanical reliability of the turbine and related equipment is determined from the turbine cycle simulation.
Effects of Nonuniform Passages on Deepfold Heat Exchanger Performance
Authors: Mondt J. R.
Published: November 2010

To realize the maximum convective transfer of heat or mass, the fins in a plate-fin type heat exchanger must be exactly spaced for an unsupported length at least eight times the fin spacing. Manufacturing tolerances cause imperfect fin spacing and fin shape. These imperfections have been statistically modeled as either nonuniform fin spacing or “bulginess.” By statistically combining nonuniform fin spacing and bulginess into a unique “total channel deviation” parameter, convective transfer penalties and flow pressure drop gains can be predicted. Predictions are supported by experimental measurements.
Characteristics of Rheinisch Brown Coals With Respect to Their Combustion and Fouling Behavior in Thermal Power Stations
Authors: Hein K.
Published: November 2010

In the paper first results of a several years’ research programme into the combustion and fouling characteristics of Rheinish brown coals are given. As described, fouling of the heat transfer surfaces causes severe difficulties for power station operation. The deposit formation is strongly dependent on both the composition of the inherent ash of the fuel and the extraneous impurities. The phenomenon of fouling can be influenced by operating parameters like excess air level and mixing between fuel and combustion air. The temperature of the heat receiving surface as well as its geometry play an important role.
Development of a Compact Gas Turbine Combuster to Give Extended Life and Acceptable Exhaust Emissions
Authors: McKnight D.
Published: November 2010

The paper describes the development history of the Olympus gas turbine combustor from the time that it was first applied to an industrial application in the early 1960s. The design improvements made — • to permit a change in fuel (from kerosene to diesel and/or natural gas), • a 60 percent increase in engine performance, and • to reduce emission levels — are detailed, and the in-service problems associated with these changes are also discussed. The emphasis is placed upon improvements in combustor life and capability to produce smoke levels well below the visible threshold, and significant success is shown to have been achieved in these two factors. The final sections of the paper are concerned with the latest on-going development effort, which is primarily to produce a low emission combustor that can be retrofitted into today’s engines.
Thermophoresis—Enhanced Deposition Rates in Combustion Turbine Blade Passages
Authors: Vermes G.
Published: November 2010

Analysis of the deposition rate in cooled and uncooled turbine cascades indicates that the temperature difference between the cooled wall and the hot working gas significantly increases the deposited fraction of the solid material, i.e., the “catch efficiency.” Data from residual oil-burning turbines show that a 300°C (572°F) temperature difference between gas and wall can cause a fifteenfold increase in deposition rate as compared with the case of the adiabatic cascade. It is proposed that the increase is due to the phenomenon called thermophoresis: Small particles moving toward colder regions under the influence of a thermal gradient in the continuum surrounding them. An approximate method of calculation is presented which is based on the Einstein/Epstein formula for thermophoresis and simplified cascade considerations; results are compared with laboratory and field data.
Generalized Fluid Meter Discharge Coefficient Based Solely on Boundary Layer Parameters
Authors: Benedict R. P.
Published: November 2010

A fluid meter discharge coefficient is developed which is based solely on boundary layer parameters. It is applicable to both pipe and plenum inlet installations. Comparisons are made between predictions based on this new formulation and the results of various published experimental work.
Maintenance Assessment for Advanced Nuclear Power Plants
Authors: Basham S. J. , Waddell J. D. , Robinson R. A. , Kok K. D.
Published: November 2010

Proper planning for maintenance and inspection tends to increase the overall availability of nuclear power plants. High potential availability is the basic measure of a successful power plant since replacement power costs are high. The study reported here compared the maintenance and inspection requirements of generic pool and loop type LMFBRs to determine if there were significant differences in these two systems owing to their fundamental difference in design. The size, number and types of failed components affected downtime for maintenance but accessibility and arrangement of components also strongly influenced the downtime.
Capital Cost System Optimization of OTEC Power Modules
Authors: Horazak D. A. , Rabas T. J.
Published: November 2010

Although the concepts of economic trade-off studies and optimization are well known, they are rarely used in large-scale design studies. The purpose of this paper is to demonstrate the feasibility of a computer system optimization program for an entire power plant, the Ocean Thermal Energy Conversion (OTEC) power module. The design and cost algorithms are discussed in general terms with emphasis on how these pieces can be developed and simultaneously integrated into the system program. A comprehensive optimization routine is presented for this complex system. A procedure is presented by which the optimum system parameters can be checked to guarantee that they are the true rather than local optimum values. Finally, the impact of enhanced heat transfer surfaces is discussed, in terms of both cost and performance.
Effects of Soil-Structure Interaction on Seismic Response of a Steel Gravity Platform
Authors: Veletsos A. S. , Boaz I. B.
Published: November 2010

After a brief review of the principal effects of soil-structure interaction on the response of structures subjected to earthquakes, a simple practical procedure is presented for evaluating these effects. The procedure is next applied to a study of the response of a proposed 400-ft steel gravity platform in 300-ft water depth, and the results of the study are discussed. The structure investigated consists of three large-diameter legs of tubular construction interconnected by a truss-type bracing system and supported on three circular pads.
An Explicit Numerical Method for the Solution of Jet Flows
Authors: Wang R. L. , du Plessis M. P.
Published: November 2010

The parabolic momentum and energy equations for axisymmetric compressible jet flows in zero pressure gradient can be expressed as first-order difference equations which relate the velocity and enthalpy at any downstream point to the velocities and enthalpies at upstream points. Using this relation, a numerical scheme is developed in such a way that the velocity, enthalpy, density, and effective viscosity at each location are expressed as Fourier cosine series thus satisfying the condition of vanishing gradients at the axis and allowing solution of the difference equations at downstream points by direct substitution of values at upstream points. The stability and accuracy are investigated by solving the momentum equations for laminar compressible flow of a hot primary jet into a colder secondary stream and for a laminar incompressible free jet at constant temperature. There is good agreement in the first case with published finite difference solutions and with experimental data in the second case. The method displays good stability and permits the prediction of velocity profiles and the axis velocity decay from known profiles at the nozzle without the use of excessive computing time.
Optimal Gate Closure Schedule for Hydroelectric Turbine System
Authors: Wozniak L. , Fett G. H.
Published: November 2010

A procedure is presented for the generation of the optimal gate closure schedule for the case of full load rejection on an isolated hydroelectric system. Constraints are placed on turbine overspeed and penstock overpressure. The optimization is carried out on the basis of minimum integral square off speed and implemented digitally by the method of steepest descent. The computation indicates that a substantial performance improvement is achieved with optimal control as opposed to the conventional.
Analysis of Steady Laminar Flow of an Incompressible Newtonian Fluid Through Curved Pipes of Small Curvature
Authors: Sankaraiah M. , Rao Y. V. N.
Published: November 2010

Steady laminar flow of an incompressible Newtonian fluid through a curved pipe of small curvature is considered. The governing equations of flow are obtained in terms of secondary flow stream function and axial velocity component as suggested by Dean. A method of successive approximations is developed to solve these equations. The first five approximations are computed. The solution obtained is used to determine the axial velocity distribution, secondary flow pattern, axial pressure drop, and pressure distribution along the pipe wall. A semiempirical equation is obtained for axial pressure drop. The theoretical results obtained are compared with the available experimental data on axial pressure drop.
Air and Water Studies on a Diffuser-Modified Flow Nozzle
Authors: Benedict R. P. , Gleed A. R. , Schulte R. D.
Published: November 2010

The effect of adding a separable diffuser to a conventional flow nozzle is studied, analytically and experimentally, concerning the flow discharge coefficient and the loss characteristic of the overall fluid meter. Comparisons between air and water tests are made on several nondimensional coordinate systems to note the effect of compressibility on the results. Agreement between existing theories, for flow coefficients and flow losses, and experimental results is shown.
Eddy-Viscosity Distribution in Thick Axisymmetric Turbulent Boundary Layers
Authors: Cebeci T.
Published: November 2010

An eddy-viscosity formulation for thick axisymmetric turbulent boundary layers is presented. Calculations made with this formulation show good agreement with experiment for both incompressible and compressible flows.
Pressure Distributions in Porous Ducts of Arbitrary Cross Section
Authors: Huang J. C. P. , Yu H. S.
Published: November 2010

A general analytical method has been developed to approximate the pressure distribution along a porous duct of an arbitrary cross section with uniform fluid extraction or addition through the wall. Application of this method is made to a variety of cross sections including circular tubes, parallel plate channels, elliptical ducts, rectangular ducts, annular ducts, and isosceles triangular ducts. Comparisons have been made with results from existing literature on cases of the circular porous tube and the parallel porous plate channel in which exact solutions are available. A numerical solution for the case of a parallel channel consisting of an impermeable wall on one side and a porous wall on the other side is also presented. One important filter duct design criterion has been found for each of the above cases. At a critical wall Reynolds number, defined by flow velocity normal to the wall and the equivalent diameter of the duct, the pressure gradient along the filter duct approaches zero. The zero pressure gradient in a filter duct ensures uniform filtration of solid particles.
A Dynamic Modeling Method of Unsteady Flows in Long Fluid Lines With Turbulent Bulk Velocities
Authors: Mercier O. L. , Wright D.
Published: November 2010

An analytical method is presented to solve the equations of unsteady gas flow in a long tube with turbulent bulk-flow velocity. The nonlinearity of the equations is overcome by judicious choice of integrating variables and by subsequent linearization, allowing integration as an ordinary matrix differential equation. The method yields, in operational form and in terms of pure time-delays, attenuations and other linear operators, a transfer matrix of the fluid line. This result can be directly implemented for line simulation or control applications; the integration process is not affected by changing end-conditions. Maximum accuracy of the resulting dynamic model is obtained for long lines (fl/D ≥ 2.2) and for small percent changes of the bulk-flow velocity along the tube. Adiabatic flow assumption and averaging of fluid properties over a cross section of tube restricts the analysis to turbulent flows and precludes the application of the model to small bulk flows.
Turbulent Viscosities for Swirling Flow in a Stationary Annulus
Authors: Scott C. J. , Rask D. R.
Published: November 2010

Developing axial and decaying tangential velocity fields are surveyed in a stationary annulus with a nearly free vortex initial swirl distribution. Isothermal air was used as the working fluid in an annulus with a single diameter ratio (di/d0 = 0.4) and at a single axial bulk Reynolds number of 1.3 × 105. The annular geometry was selected because the inner and outer wall curvatures yield opposite effects on the swirl turbulence. The discussion is centered on a critical exposure of the data reduction techniques (momentum integrals) for obtaining the radial variations of the axial and tangential momentum diffusivities.
The Determination of Wall Friction for Vertical and Horizontal Two-Phase Bubbly Flows
Authors: Davis M. R.
Published: November 2010

The one-dimensional momentum equation without slip is applied to the bubbly flow of air-water mixtures in pipes for Reynolds numbers in excess of 105. The equation is integrated along the pipe so that pressure measurements made over a finite length of pipe may be used to determine the surface friction factor. The critical void fraction for the flow is found to characterize the flow. The results show a variation of friction factor with Reynolds number similar to that found in single-phase flows but with values approximately 10 percent greater, provided the critical void fraction is less than 0.85. For larger values, it is found that the results indicated lower values of the friction factor which depart from the general trend of the rest of the data. Similar effects were observed for both vertical and horizontal flows.
On a Test of the Resonance Hypothesis
Authors: Mujumdar A. S. , Douglas W. J. M.
Published: November 2010

This note presents results of an experimental test of van der Hegge Zijnen’s resonance hypothesis. Near wake turbulence spectra obtained over a range of stream turbulence intensities and integral scales revealed no preferential amplification of turbulent fluctuations at or near the Strouhal frequency thus invalidating predictions of the resonance hypothesis.
The Effect of Inlet Velocity Profile Shape on Flow Separation in a Confined Two-Dimensional Channel
Authors: Peters A. R. , Phelps G. A.
Published: November 2010

Results of a previously developed numerical relaxation method were employed to determine the effect of different inlet profiles on separation in a two-dimensional channel with a right angle bend. The extent of separation and velocity distribution downstream from the corner was found to be relatively independent of the inlet profile selected.
Calculation of the Development of Turbulent Boundary Layers With a Turbulent Freestream
Authors: Evans R. L. , Horlock J. H.
Published: November 2010

An existing integral boundary layer calculation procedure is modified to predict turbulent boundary layers developing in a turbulent freestream. Extra terms in both the turbulence model equation and the momentum integral equation are introduced to account for the effects of freestream turbulence. Good agreement with flat plate boundary layer measurements in a turbulent freestream has been obtained, while comparison with measurements in a severe adverse pressure gradient shows qualitative agreement with experiments.
Load Level Tuning of Governor Gains for Suboptimal Speed Control of Hydroelectric Installations
Authors: Wozniak L.
Published: November 2010

Present speed control governors for hydroelectric installations employ constant gain settings. This paper develops appropriate gain functions of load level for optimal (deadbeat sense) transient response throughout the operating range. The results coincide with the Paynter numbers for the special case of best efficiency operation and consider the null conduit and reverse blading effects as additional special cases.
Influence of Entrained Water Mass on the Vibration Modes of a Shell
Authors: Horvay G. , Bowers G.
Published: November 2010

The virtual mass effect of a liquid annulus surrounding a shell is established in closed form. Simple support conditions for the shell and open end conditions for the liquid annulus are considered. In this fashion one arrives at a generalization of Stokes’ formula which treats the case when a rigid rod moves back and forth in the liquid. The present theory encompasses vibrations of the beam mode and breathing mode types. Availability of the entrained liquid mass expression is of importance in the computation of reactor and missile vibrations. The results for the beam modes of shell vibrations, for the example considered, are in satisfactory agreement with previous results obtained on the basis of beam analysis.
Momentum Integral for Curved Shear Layers
Authors: So Ronald M. C.
Published: November 2010

If the exact metric influence of curvature is retained and the displacement effect neglected, it can be shown that the momentum integral for two-dimensional, curved boundary-layer flows is identical to the von Karman momentum integral. As a result, attempts by previous researchers to account for longitudinal curvature effects by adding more terms to the momentum integral are shown to be correct.
Multistable Effect Associated With Axially Opposed Sonic Air Jets
Authors: Chubb Thomas L.
Published: November 2010

During the study of two axially opposed choked air jets, an unusual effect has been noticed with respect to the impingement plane of the jets. In spite of the fact that both jets were operating at the same pressure ratio, the impingement plane was not necessarily centered between the two nozzle exits. Under certain conditions, the impingement plane had several stable locations along the axis between the two nozzles.
Experimental Results and Analysis of Flow in a Pneumatic Tube System During a Vehicle Transit
Authors: Cudlin J. J. , Harman C. M.
Published: November 2010

A pneumatic tube system suitable for transportation purposes is simulated in an experimental facility. The vehicle position, velocity and corresponding system pressures were obtained and are presented for representative test runs. An analysis for prediction of these quantities during the transit of a vehicle through a tube under conditions of fixed inlet pressure and discharge volume flow rate is also presented. This analysis is applied to the experimental operating conditions and is shown to predict the experimental results closely and to be applicable to the prediction of the performance of prototype pneumatic tube systems over a significant range of interest.
A Reynolds Stress Model for Turbulent Corner Flows—Part I: Development of the Model
Authors: Gessner F. B. , Emery A. F.
Published: November 2010

A Reynolds stress model is proposed for modeling the local turbulence structure in flow along a streamwise corner. Initial discussion centers on present methods of predicting internal and extenal corner flow behavior. An algebraic Reynolds stress model is then developed by operating on a modified form of the Reynolds stress transport equations. Application of the model involves specification of two empirical constants and a global representation for the mixing length. The paper concludes with a discussion of the features and limitations of the model.
An Approximate Method for the Solution of a Class of Nonsimilar Laminar Boundary Layer Equations
Authors: Nath G.
Published: November 2010

An approximate method is developed for locally nonsimilar laminar boundary layer flows. This method is applicable to several boundary layer velocity problems where the nonsimilarity stems from the freestream velocity distribution and the transverse curvature. The results are compared with those obtained by other methods and, except in the neighborhood of the point of separation, they are in good agreement.
The Response of a Developed Turbulent Boundary Layer to Local Transverse Surface Motion
Authors: Lohmann R. P.
Published: November 2010

Measurements were obtained of the mean velocity, Reynolds stress tensor components and spectral distribution of turbulent energy in a boundary layer that was adjusting spatially from a collateral to a three-dimensional state because of transverse motion of the bounding wall. The results indicate that changes to the turbulent structure lead to a strong coupling between the axial and transverse components of mean velocity. The influence of the imposed motion was found to be confined to a discrete region near the wall over the first ten initial boundary layer thicknesses, after which it became more global in nature.
Turbulent Boundary Layers on Centrifugal Compressor Blades: Prediction of the Effects of Surface Curvature and Rotation
Authors: Johnston J. P. , Eide S. A.
Published: November 2010

A method for calculation of turbulent boundary layers on curved, rotating surfaces is presented, and the applicability of the method to the prediction of attached flow over compressor rotor blades is indicated. Calculated results are compared to existing data sets. Additional sample calculations to study the effects of rotation are also presented. Correlations of these calculated results provide a simple method for estimation of the effects of rotation on skin friction, cf, and boundary-layer shape factor, H.
Vibration of Deriaz Pumps at Dos Amigos Pumping Plant
Authors: Ruud F. O.
Published: November 2010

Severe vibration problems were encountered during initial operation of large Deriaz pumps. This paper describes those problems, the alternative solutions available, and the corrective action taken. Transient shaft vibrations prevented normal pump shutdown operation, when severe counter-rotational whirl occurred as the shaft speed decreased. Vibration at low blade angles preclude operation below half the rated flow. High intake water levels led to rotational shaft whirl in the normal operating range. Subsequent field testing evaluated various possible sources of vibration excitation, and verified the remedy of air injection into the headcover.
A Simple Linearized Hot-Wire Anemometer
Authors: Miller James A.
Published: November 2010

The circuit and application of an inexpensive simple linearized hot wire anemometer especially suited to turbulence research in incompressible media is described. Special features of the design are very high stability, simple bridge adjustment, and a linearizer having an adjustable exponent and very high transfer function accuracy. Measured frequency response is in excess of 100 kilohertz for the bridge and 7.5 kilohertz for the linearizer.
A Nearly Three-Dimensional Intrablade Computing System for Turbomachinery
Authors: Novak R. A. , Hearsey R. M.
Published: November 2010

The structure of a computing system for bladed or unbladed turbomachinery passages is described and discussed. The system, in an overall sense, is modeled after the work of Wu, and is comprised of two coordinated computer programs, one providing solutions on rotationally symmetric blade-to-blade surfaces and the second on streamsheets roughly parallel to the blades. Both approaches utilize streamline curvature techniques.
On the Calculation of Three-Dimensional Divergent and Rotational Flow in Turbomachines
Authors: Ribaut M.
Published: November 2010

This study deals with the calculation of the three-dimensional steady flow of a compressible and viscous fluid through a turbomachine. Using the potential theory, a quasi three-dimensional method is developed, which reduces the simplifying assumptions and yields high numerical accuracy. The method includes all main effects induced by the primary vortex system, in particular the influence of the casing and blade boundary layers on the cascade circulation. The use of two vortex sheets, representing the boundary surface, makes the calculation of flows having strong developed or separated boundary layers possible and allows a direct calculation of the secondary vorticity. Computed divergent and rotational flows are presented and compared with exact solutions or experimental data.
Modified Tietjens Function for Asymptotic Analysis of Shear Flow Stability
Authors: Hussain A. K. M. F. , Reynolds W. C.
Published: November 2010

In asymptotic analysis of the hydrodynamic stability of shear flows, the viscous effects enter through the modified Tietjens Function, which is used in the graphical determination of the eigenvalues. For neutral normal modes the argument of this function is real, and values of the function have been calculated previously. For non-neutral normal modes the argument is complex; the present note gives the modified Tietjens Function for complex arguments. This function is particularly useful in investigating the behavior of lightly damped eigenmodes for shear flows of arbitrary velocity profile.
Some Characteristics of High Waves in Closed Channels Approaching Kelvin-Helmholtz Instability
Authors: Kordyban E.
Published: November 2010

The characteristics of water waves produced by flowing air in closed channels were studied to uncover the effects of surface pressure variation. From theoretical considerations, it is proposed that the point of onset of the Kelvin-Helmholtz instability for such waves may be found from 1.35ρaρwVc2ghc=1 Photographs of internal flow patterns and wave shapes confirm the occurrence of this instability, but the theoretically predicted reduction in wave celerity does not occur. The wave celerity for high waves was found to be predictable by the formula C=0.191gLtanh2πhwL1/2 The measured height to length ratios for the highest observed waves are of the order of 0.1.
Deposition of Suspensions in the Entrance of a Channel
Authors: Eldighidy S. M. , Chen R. Y. , Comparin R. A.
Published: November 2010

An analytical investigation of the mechanics of deposition in a channel from the channel inlet to a distance of 7 channel depths has been made and a mathematical model developed for the deposition process from which the most significant parameters affecting the deposition can be identified. The analysis is restricted to laminar flow of dilute suspensions with electro-static charge and surface adhesion and without gravitational force. The results show that the electrostatic charge has the most effect on deposition. The other parameters included in the study are Knudsen number, momentum-transfer number, Reynolds number, diffusive Peclet number.
Dynamics of Heat Exchanger Tube Banks
Authors: Chen S. S.
Published: November 2010

Flow-induced vibration in heat exchanger tube banks is of great concern, particularly in high performance heat exchangers used in nuclear raactor systems. In this paper, the dynamic characteristics of tube banks in stationary liquid are studied. A method of analysis is presented for free and forced vibrations of tube banks including tube/fluid interaction. Numerical results are given for tube banks subjected to various types of excitations.
Effect of Density Change on the Solidification of Alloys
Authors: Tien R. H. , Koump V.
Published: November 2010

During freezing of alloys the difference in densities between the solid and the liquid results in a mass flow throughout the solid-liquid region. This mass flow contributes to transport of mass and heat and hence affects the rate of solidification of the alloy. In this paper an analytical solution is presented on solidification of a semi-infinite slab of a binary alloy at a constant surface temperature and unequal solid and liquid densities. On the basis of an assumed form of the solid fraction distribution within the solid-liquid region, this solution yields the temperature and liquid velocity distribution within the solid-liquid region, the temperature distribution within the solid skin and the rates of propagation of the solidus and the liquidas fronts. A comparison is made with the case of equal solid and liquid densities.
Measurement of Monochromatic Emittance of Nonconductors at Moderate Temperatures
Authors: McCulloch John W. , Sunderland J. Edward
Published: November 2010

The measurement of the monochromatic emittance of thermal insulators at temperatures near room temperature is discussed. Results for the spectral emittance of freeze-dried beef are presented. For temperatures between 115 F and 125 deg F, the emittance is between 0.7 and 0.85. These values compare favorably with existing total emittance data. A discussion of the error involved in making such measurements is discussed in detail.
An Analytical Investigation of Free Convection Heat Transfer to Supercritical Water
Authors: Nowak E. S. , Konanur A. K.
Published: November 2010

Heat transfer to supercritical water (at 3400 psia in the pseudocritical region) by stable laminar free convection from an isothermal, vertical flat plate was analytically investigated. The actual variations with temperature of all or some of the thermophysical properties of supercritical water were taken into consideration. Fair agreement was found between the analytical values of this paper and existing experimental data.
Transition From the Turbulent to the Laminar Regime for Internal Convective Flow With Large Property Variations
Authors: Coon C. W. , Perkins H. C.
Published: November 2010

The results of a primarily experimental study of the transition from turbulent flow to laminar flow as a consequence of high heating rates are presented. Results are reported for hydrodynamically fully developed, low Mach number flows of air and helium through a vertical, circular tube. The electrically heated section was 100 diameters in length; entering Reynolds numbers ranged from 1700–40,000, and maximum wall-to-bulk temperature ratios reached 4.4. As a means of predicting the occurrence of a transition from turbulent flow to laminar flow, the experimental results are compared to the acceleration parameter suggested by Moretti and Kays and to a modified form of the parameter that is appropriate to a circular tube. It is suggested that the variable property turbulent flow correlations do not provide acceptable predictions of the Nusselt number and the friction factor if the value 4μq′′G2DTcp≃1.5×10−6 based on bulk properties, is exceeded for an initially turbulent flow situation. It is further suggested that Nusselt numbers and friction factors at locations down-stream from the point xDlaminar≃(2×10−8)(Tinlet)(Reb,inlet)2TwTbmax−1 for bulk temperatures in degrees Rankine may be obtained from the laminar correlation equations even though the flow is initially turbulent.
A Study of Heat Driven Pressure Oscillations in a Gas
Authors: Feldman K. T. , Carter R. L.
Published: November 2010

Large amplitude acoustical pressure oscillations can be generated in a gas by a steady heat addition. The thermoacoustical oscillation known as the Sondhauss oscillation occurs in a pipe having only one closed end. Experiments were performed to determine thermoacoustic oscillator characteristics for different system geometries and for different operating conditions. Based on these experimental studies, a physical explanation of the mechanism causing Sondhauss thermoacoustical oscillations is presented. The driving mechanism consists of two separate components, that of driving by simple thermal expansion, and that of expansion by the mixing of hot and cold gas in the pipe. The initiation of the oscillations is discussed. Thermoacoustic oscillation phenomena are shown to be analogous to the interaction occurring in a regenerative heat engine, where a steady heat input causes an oscillating mechanical energy output. A comparison of experiment and generalized theory is presented.
Analytical Solution to Steady-State Heat-Conduction Problems With Irregularly Shaped Boundaries
Authors: France D. M.
Published: November 2010

A method of obtaining an analytical solution to two-dimensional steady-state heat-conduction problems with irregularly shaped boundaries is presented. The technique of obtaining the coefficients to the series solution via a direct least-squares approach is compared to the “point-matching” scheme. The two methods were applied to problems with known solutions involving the three heat-transfer boundary conditions, temperature, heat flux, and convection coefficient specified. Increased accuracy with substantially fewer terms in the series solution was obtained via the least-squares technique.
Infrared Radiation of Thin Plastic Films
Authors: Tien C. L. , Chan C. K. , Cunnington G. R.
Published: November 2010

A combined analytical and experimental study is presented for infrared radiation characteristics of thin plastic films with and without a metal substrate. On the basis of the thin-film analysis, a simple analytical technique is developed for determining band-averaged optical constants of thin plastic films from spectral normal transmittance data for two different film thicknesses. Specifically, the band-averaged optical constants of polyethylene terephthalate (Mylar, DuPont Co.) and polyimide (Kapton, DuPont Co.) were obtained from transmittance measurements of films with thicknesses in the range of 0.25 to 3 mil. The spectral normal reflectance and total normal emittance of the film side of singly aluminized films are calculated by use of optical constants; the results compare favorably with measured values.
Periodic Heat Transfer in Straight Fins
Authors: Yang J. W.
Published: November 2010

The characteristics of heat transfer in straight fins with periodic variation of base temperature have been determined analytically. The heat-transfer process is governed by three dimensionless parameters: the conventional fin parameter N, the frequency parameter B, and the amplitude parameter A. The effects of these parameters on the instantaneous and average heat flow rates, axial and time-wise temperature distributions, and instantaneous and average fin efficiencies are demonstrated by several examples. In general, the time-average fin efficiency is reduced by the periodic variation of the base temperature.
A Parametric Study of the Transient Ablation of Teflon
Authors: Clark Barry L.
Published: November 2010

An analytical and experimental investigation was performed to simultaneously determine 18 ablation heat-transfer parameters for Teflon by the method of nonlinear estimation. A transient one-dimensional ablation model solved numerically was utilized to represent the thermal response of Teflon samples that were instrumented in-depth with thermocouples. The nonlinear estimation computer program was based on a modified version of Marquardt’s algorithm. A matching of the predicted and measured temperatures was effected and the results for the parameter values were in accord with available information in the literature. It was concluded that the ablation model accurately predicted the transient thermal response and surface recession of ablating Teflon.
Film Boiling on Vertical Surfaces
Authors: Suryanarayana N. V. , Merte H.
Published: November 2010

Film boiling of a saturated liquid on a vertical surface is analyzed to determine the local heat-transfer rates as a function of height and heater-surface superheat. Experiments show that the laminar-flow model is inadequate. A turbulent-vapor-flow model is used, and the influence of the interfacial oscillations is incorporated on a semiempirical basis. Measurements of local film boiling were obtained with a transient technique using saturated liquid nitrogen.
Performance Prediction of Falling-Film Evaporators
Authors: Chun K. R. , Seban R. A.
Published: November 2010

Three experimental results in the literature involving the evaporation of water and of brine in falling-film evaporators have been compared to predictions in which were used the local heat-transfer coefficients experimentally correlated as h = A(Λ/μ)n, where the constants A and n take on different values depending on the flow regime of the falling film, and (4Λ/μ) is the film Reynolds number. The relatively good accord between theory and experiment supports the use of those coefficients for design.
The Numerical Simulation and Design of a Homogeneous Nonisothermal Multi-pass Shell-and-Tube Reactor
Authors: Smith T. G. , Banchero J. T.
Published: November 2010

The simulation of a multi-pass shell-and-tube reactor requires the solution of a nonlinear two-point boundary-value problem. Six nonlinear ordinary differential equations describing the production of ethanolamines in 1–2 and 1–4 shell-and-tube reactors are solved numerically using both a quasi-linearization algorithm and a classical shooting method. Despite the presence of five unknown initial values, the shooting-method approach proved superior for this particular problem. The simulation revealed that for exothermic reactions the optimum tube-side temperature profile (and therefore the minimum-size reactor) was most closely approached by designing for the lowest overall heat transfer coefficient and cooling-water flow rate and highest inlet cooling-water temperature, subject to the constraint of a maximum-reaction mixture temperature.
The Sonic Limit in Sodium Heat Pipes
Authors: Levy E. K. , Chou S. F.
Published: November 2010

The results of an analytical study of the vapor dissociation–recombination and homogeneous vapor condensation phenomena in sodium heat pipes are described. It is shown that neither the dissociation–recombination reaction nor the vapor condensation process has a large influence on the sonic-limit heat transfer rate. The single most important factor is shown to be the wall shear stress in the heat-pipe vapor passage. The friction effects control the location of the sonic point, determine if the flow in the condenser section will be subsonic or supersonic, and decrease the sonic-limit heat transfer rate to values which can be substantially lower than those which are predicted from inviscid analyses.
Similar Solutions for Laminar Film Condensation with Adverse Pressure Gradients
Authors: Beckett P. M.
Published: November 2010

Steady two-dimensional laminar film condensation is investigated when the saturated vapor has the Falkner–Skan mainstream. Numerical solutions and approximate models are discussed with reference to other published work.
Transient Heat Conduction in an Infinite Plate With a Transverse Circular Cylindrical Hole
Authors: Michalopoulos C. D. , Seco J. J.
Published: November 2010

The flow of heat in an infinite plate with a transverse circular cylindrical hole is considered. The boundary conditions are zero temperature on the cylindrical surface and arbitrary but axisymmetric temperature distributions on the plane surfaces. The solution is obtained by means of Laplace and an unconventional Hankel transforms. Numerical results are given in graphical form for a plate with a step temperature distribution on one face and zero temperature on the other.
Determination of Turbulent Exchange Coefficients in a Rod Bundle
Authors: Roidt M. , Pechersky M. J. , Markley R. A. , Vegter B. J.
Published: November 2010

A tracer gas is injected into a single subchannel of a large air flow model of a reactor rod bundle. Axial variations in the tracer flux are determined by sampling at two downstream positions in both the injection subchannel and those adjacent to it. This information, with measured subchannel area changes, is used to calculate crossflows and the turbulent eddy diffusion coefficient. The latter number agrees with the results of other investigators in regular pipe flows. Also determined are distributional factors which would be required for modeling the transport equations, for this particular scalar distribution, with a typical lumped parameter computer code.
A Theoretical Study of Dropwise Condensation
Authors: Tanaka Hiroaki
Published: November 2010

The so-called steady dropwise condensation consists of the transient dropwise condensation occurring repeatedly from place to place on the tracks of departing drops. By taking statistical and geometrical conditions into account, the author derives fundamental equations describing the process of this transient dropwise condensation. By solving these equations, the existence of a universal drop-size distribution is predicted. Further, by introducing a model for the cycle of drop departure, a general expression for the heat-transfer coefficient under the so-called steady dropwise condensation is obtained.
An Investigation of the Collapse and Surface Rewet in Film Boiling in Forced Vertical Flow
Authors: Iloeje O. C. , Plummer D. N. , Rohsenow W. M. , Griffith P.
Published: November 2010

A transient boiling experiment has been run in such a way that one can acquire data in forced convection film, transition, and nucleate boiling regions for a specified pressure, quality, and mass flux. Transient boiling experiments were conducted at the Nuclear Energy Division of the General Electric Company for water in a 0.492 in. ID inconel X-750 tube at mass fluxes of 50,000, 100,000, and 250,000 lbm/hr-ft2, quality range of 30–100 percent and a pressure of 1000 psia. The reduced boiling curves for these data indicated temperature differences at burnout on the order of 100–200° F and temperature differences at the minimum ranging from 700 to 1100° F. These results (higher than in other experiments) are felt to be caused by scale deposit, axial conduction, and roughnesses on the test surface. Physical evidence indicates that the test surface became coated with an appreciable scale deposit when subjected to the initial temperatures in excess of 1500 °F in a steam atmosphere. It has been found (reference [1]) that BWR fuel will normally have scale deposit on the heat transfer surface and thus the qualitative effects of scale deposits in this report are expected to apply in BWR Loss-of-Coolant accident evaluation. An empirical correlation was developed for the data for minimum film boiling temperature differences. The correlation was based on Berenson’s minimum pool film boiling temperature difference correlation in order to provide a technique for extrapolating to different pressures.
Augmentation of Heat Transfer in a Laminar External Gas Boundary Layer by the Vaporization of Suspended Droplets
Authors: Bhatti M. S. , Savery C. W.
Published: November 2010

A theory is developed for the restricted regime of two-phase flow wherein droplets suspended in a gas stream penetrate the boundary layer and vaporize without deposition. The equations of motion of the droplets are derived taking into account Stokes’ drag, buoyancy, and gravity forces. Superimposed free stream turbulence propels a fraction of the droplets into the boundary layer. Using these results a two-region model is developed for determining the heat transfer rate. The application of the theory is illustrated by calculating several quantities of practical interest for the finned surface of a dry cooling tower.
Axial Heat Conduction Effects in Forced Convection Along a Cylinder
Authors: Chen T. S. , Lohman M. E.
Published: November 2010

An analytical study is performed to determine the effects of axial heat conduction and transverse curvature on laminar forced convective heat transfer of liquid metals along a circular cylinder. The flow and thermal boundary layers for this problem are nonsimilar, the non-similarity arising both from the transverse curvature ξ = (4/R)(νx/u∞)1/2 of the cylindrical surface and from the axial heat conduction effect expressible as Ω = 1/Pex, where Pex is the local Peclet number. The governing equations are solved by the local nonsimilarity method in which all the terms in the conservation equations are retained and only terms in the derived subsidiary equations are selectively deleted according to the levels of truncation. Numerical results are presented for liquid metals having representative Prandtl numbers of 0.03, 0.008, and 0.003 over a wide range of ξ values from 0 (i.e., a flat plate) to 4.0 and Ω values from 0 (i.e., without axial heat conduction effect) to 0.20. The results indicate that the local surface heat transfer rate increases with an increase in the transverse curvature of the cylindrical surface, an increase in Prandtl number, and an increase in the axial heat conduction parameter or a decrease in Peclet number.
Analytical and Experimental Investigation of Self-Freezing
Authors: Hayashi Y. , Komori T. , Katayama K.
Published: November 2010

The problems of the self-freezing of a wet substance were treated as a heat conduction problem with phase change in the case of multiphase substance. The solutions for this problem were derived from the analytical procedure of Neumann’s solution and were compared with the experimental results obtained through the self-freezing of the bed with wet glass powder.
The Thermodynamics of Intracellular Ice Nucleation in the Freezing of Erythrocytes
Authors: Toscano W. M. , Cravalho E. G. , Silvares O. M. , Huggins C. E.
Published: November 2010

A theoretical model describing the thermodynamics of intracellular ice nucleation is developed for red blood cells as a model biomaterial. Analytical expressions based on current theories of ice nucleation by both homogeneous and heterogeneous nucleation processes are coupled with a thermodynamic model for the loss of intracellular water during freezing. Numerical solutions for both modes of nucleation identify two cooling regions—high cooling rates and low cooling rates—separated by a sharp demarcation zone. The nucleation temperature for high cooling rates is approximately 20° K higher than the nucleation temperature for low cooling rates and is essentially independent of cooling rate in each region. The nucleation temperatures for heterogeneous nucleation are approximately 30° K higher than the nucleation temperatures for homogeneous nucleation in the two regions. For the case of heterogeneous nucleation, it is possible to increase the nucleation temperature by packing of catalysts via the concentration polarization effect. If the cell suspension is allowed to supercool before nucleation occurs in the extracellular medium, the sharp transition from low cooling rates to high cooling rates for heterogeneous nucleation shifts to much lower cooling rates. The dependence of the transition cooling rate on the degree of supercooling has been established for a typical freezing situation.