bluuebunny/crossref_metadata_2025 huggingface dataset:
Factors Influencing Precision Agriculture Tools or Technologies Adoption in Egypt
Authors: Elsafty Ashraf , Atallah Antionette
Published: July 2022

Precision Agriculture Technologies (PATs) are advocated as inevitable agricultural practices to achieve the highest economic value and mitigate the environmental impact of the agriculture.Water scarcity and rapid population growth in Egypt endanger the economic nourishment. Since agriculture consume more than 80% of total water consumption in Egypt; it is important to adopt efficient practices without sacrificing high productivity and minimize environmental degradation. This thesis studies the factors influencing PATs adoption in Egypt. Based on the literature review; there are 5 constructs with 15 independent variables are tested in this study. The constructs are as follows; (1) Socio Demographic Factors; studying effect of farmer age, level of education, years of experience. (2) Agro Ecological Factors; including farm size, land tenure, farm crops. (3) Financial Factors; encompasses farm income, investment cost, perceived economic benefits and perceived environmental benefits. (4) Technological Factors; testing impact computer and smart phone usage, PATs and PI Usage and perceived ease of use. (5) Institutional Factors: investigating effect of farm region and development pressure. Non-probability sampling was used in this study with convenience and snowball techniques to collect data. The data was collected from 32 farms distributed in Lower and Upper Egypt via an online survey published through Social Media Channels. Respondents were the farm owners and farm operators as each one represents one farm only. The analysis was performed using SPSS to discover factors impacting PATs adoption. Results show that perceived environmental benefits and development pressure are statistically significant factors affecting PATs adoption in Egypt.To conclude, this study provides insightful results regarding what influences the Egyptian farmers in PATs adoption and this may provide better understanding for policy makers to better formulate incentive programs and regulation to motivate farmers to adopt more PATs. Moreover, these results can be used by service providers to enhance marketing.
Fast Thermocouples as Control-System Elements Sensing Exhaust-Gas Temperatures in Aircraft Gas Turbines
Authors: Alford J. S. , Heising C. R.
Published: July 2022

Factors which favor the use of thermocouples as control-system elements sensing exhaust-gas temperatures in aviation gas turbines are presented, as well as the development of a construction having adequate strength to withstand vibration. The authors give analytical and experimental determinations of the time constant of thermocouples and present a mathematical analysis of the effect on time constant of conduction along the thermocouple wire to the support. The paper also includes a discussion of the recovery factors of thermocouples and an evaluation of the error introduced when a number of thermocouples that read different temperatures are connected in parallel.
Flame Velocities in Carbon Monoxide-Oxygen Mixtures
Authors: Price T. W. , Potter J. H.
Published: July 2022

One of the ideal theoretical devices for determining flame velocities is the constant-pressure adiabatic bomb. In practice this has been realized in the form of a soap bubble filled with a premixed gas-oxidant combination, centrally ignited by a spark, and observed by high-speed photography. However, the aqueous soap film imposed certain restrictions, in that moisture content was not controllable, and that the film itself might have taken some part in the combustion reaction. The present paper reports (a) on a search for a substitute material for the bomb, and (b) the development of a technique in which a very thin transparent rubber balloon was used. The new method was then used to determine flame velocities in carbon monoxide-oxygen mixtures saturated with water vapor. These velocities were found to increase with increase of initial mixture temperature.
Local Heat-Transfer Coefficients on the Surface of an Elliptical Cylinder in a High-Speed Air Stream
Authors: Seban R. A. , Drake R. M.
Published: July 2022

Local heat-transfer coefficients and recovery factors have been determined for an elliptic cylinder of 1:4 axis ratio at zero and at a 5-deg angle of attack in an air stream. These results are presented for Reynolds numbers from 607,000 to 1,330,000, for which the onstream Mach numbers were from 0.20 to 0.53.
Seals to Minimize Leakage at Higher Pressure
Authors: Niemeier B. A.
Published: July 2022

Fixed and moving seals to be used in the super-pressure range, 10,000 to 100,000 psi, as classified by the author, are studied and evaluated. A general discussion of the theoretical problems in confining pressures of great magnitude precedes methods for designing seals for such pressures. A method and device for evaluating seals has been developed to provide confirmation of theories. Practical seal problems and applications are shown.
Influence of Unheated Starting Sections on the Heat Transfer From a Cylinder to Gas Streams Parallel to the Axis
Authors: Tessin William , Jakob Max
Published: July 2022

The present investigation, sponsored by the U. S. Naval Postgraduate School and performed in Illinois Institute of Technology, is an extension of the work of Jakob and Dow dealing with the heat transfer between a cylinder and air flowing parallel to the longitudinal axis. Spherically tipped nosepieces of various lengths were attached to an electrically heated cylinder. The results show that the heat transfer is a function of the ratio of heated length to total length. Comparison of the results with those of Jakob and Dow indicates a decrease of the heat transfer with increasing cylinder radius. Extrapolation to infinite radius (flat plate), however, is uncertain. Therefore, it is recommended that an average value of the heat-transfer coefficient be used independent of the curvature pending further studies of the influence of configuration and turbulence level.
Radioactive Cutting Tools for Rapid Tool-Life Testing
Authors: Merchant M. E. , Ernst Hans , Krabacher E. J.
Published: July 2022

This paper presents an abbreviated method of measuring cutting-tool life using radioactive isotopes as tracers to measure the “instantaneous” rate of tool wear. This method consists of machining with a tool which has been rendered radioactive by neutron irradiation in a nuclear reactor, collecting the resulting chips, and measuring their radioactivity due to the particles abraded from the tool during a few seconds of cutting. The paper describes the preparation necessary, together with the equipment and techniques which were evolved in order to develop this test method. Data from tests conducted with various tool materials, work materials, rake angles, and cutting fluids are presented and analyzed. The results of special studies of the tool-wear mechanism also are presented.
Tubular Air-Heater Problems
Authors: Rothemich E. F. , Parmakian G.
Published: July 2022

This paper discusses the occurrence of air-heater deposits, their effect on performance, maintenance, and design. Actual operating experiences and a survey of a large number of installed tubular air heaters are given to show the extent of the air-heater problems being encountered by steam-generating units fired with pulverized coal, stoker, natural gas, and oil. Suggestions are offered as to methods for minimizing these difficulties by design and operation.
Experimental Evaluation of Expansion Factors for Steam
Authors: Murdock J. W. , Foltz C. J.
Published: July 2022

The empirical expansion factor for the orifice-metering of compressible fluids is based largely on tests of natural gas and air. This paper presents data on superheated steam for orifice ratios from 0.30 to 0.82, superheats from 29 to 255 F, and pressures of 44 to 102 psia. Expansion factors obtained were in close agreement with those of natural gas and air.
On the Solution of the Reynolds Equation for Slider-Bearing Lubrication—V: The Sector Thrust Bearing
Authors: Charnes A. , Saibel E. , Ying A. S. C.
Published: July 2022

In an earlier paper (1) the authors developed an exact solution of the Reynolds equation for the slider bearing when the film thickness varied in an exponential manner. It was shown that this solution could be used as an approximate solution for the plane inclined slider, with good accuracy. Furthermore, the expressions for the pressure, total load, friction force, oil flow, and side leakage, and center of pressure were easily calculated from series which converged rapidly for all values of the parameter involved. It is the object of the present paper to develop a similar solution for the sector thrust bearing with side leakage for which no reasonably practical solution exists at the present time. For that reason recourse has been had in the past to analog solutions (2), numerical solutions (3), or approximations by means of analogous problems (4). In the numerical case any change in a dimension or parameter may necessitate a completely new solution, while in the others it is difficult to get good accuracy.
Cavitation Tests on Hydrofoils in Cascade
Authors: Numachi Fukusaburō
Published: July 2022

First treated is theoretical basis of the cavitation tunnel for experimental hydrofoils in cascade, the following two points especially being taken into account: (a) The impossibility of arranging an infinite number of hydrofoils in an actual experiment. (b) The inevitable effects of wall interference in the working section.
Investigation of Gravity Reinjection of Fly Ash on a Spreader-Stoker-Fired Boiler Unit
Authors: Morrow C. H. , Holton W. C. , Wagner H. L.
Published: July 2022

The subject of fly-ash collection and disposal on spreader-stoker-fired boiler units has received considerable study ever since this method of fuel burning came into extensive use. The J. I. Case Company has carried on considerable study and experimentation on this subject in connection with a rehabilitation and modernization program of its power plants started in 1941. This work along with the over-all performance records obtained from the Tractor Works Plant of the company has received considerable attention from engineers both in this country and abroad. In November, 1949, a new 100,000-lb-per-hr boiler unit was put into operation which incorporated, in so far as known, the first system of gravity return of fly ash from the dust collector to the boiler furnace. This installation was called to the attention of Bituminous Coal Research, Inc. (BCR), by W. S. Major, then a development engineer with that organization. As a result of his initiative and efforts, a test program was initiated to investigate the over-all results obtained with this system under the joint sponsorship of the Detroit Stoker Company, BCR, and the J. I. Case Company. Battelle Memorial Institute was engaged to supervise and conduct the tests. The purpose of this paper is to report some of the test results obtained.
Large-Forging-Press Operations and Production Problems
Authors: Motherwell G. W. , Douslin J. R. , Rustay A. L.
Published: July 2022

Examples of forging-design problems and progress are shown and discussed, illustrating recent advancements in the production of forgings with thin webs, smaller fillet and corner radii, and closer tolerances. Advancements in manufacturing techniques are described, including new processing methods and equipment. Factors affecting procurement time and cost are discussed.
Damage Prevention From Diesel Engine Crankcase Explosions
Authors: Cavileer A. C.
Published: July 2022

As the largest user of Diesel engines in the world the Navy Department is greatly concerned in solving the problems involved in crankcase explosions, and providing adequate means to minimize the hazard to personnel and equipment. The general problem is stated in the paper, and the test work being undertaken by the author’s branch is described. Results are given and recommendations for adequate pressure-relief arrangements.
Diesel Engine Crankcase-Explosion Investigation
Authors: Ferguson G. W.
Published: July 2022

The purpose of this paper is to present information gained from a study of the lubricating-oil aspects of crankcase explosions. Experimental tests indicate the crankcase atmosphere of a Diesel engine is a potentially inflammable mixture of oil mist and air in which ignition may be initiated by an overheated part. The minimum ignition temperature of an oil mist/air mixture is reduced by decreased air flow, increased mixture temperature, and increased igniter size. No significant differences were found in the minimum ignition temperature of a wide variety of lubricating oils, even when diluted with up to 20 per cent Diesel fuel. As long as inflammable lubricants are employed, it appears that little can be done from a lubricating-oil or fuel standpoint to prevent crankcase explosions. It is indicated that the problem may best be attacked by further critical studies of operation and maintenance practices and continued refinements in engine design.
Nondimensional Compressor Performance for a Range of Mach Numbers and Molecular Weights
Authors: Sheets H. E.
Published: July 2022

The performance of centrifugal compressors is analyzed on the basis of nondimensional pressure and impeller-exit flow coefficients ψ and ϕ2. Use of these coefficients for impellers of high solidity permits presentation of compressor performance in a single curve for all conditions up to a critical Mach number. To show compressor data in a characteristic family of curves, performance is represented by pressure and flow coefficients KP and KQ. These coefficients take into account the coefficient of compression and the molecular weight simultaneously with the induction temperature. Test data for two compressors are presented over a range of Mach numbers from 0.36 to 2.0, and molecular weights in the range of that of air to heavy refrigerants. The test data show experimental verification of the fact that for centrifugal turbomachines with blades of high solidity the performance is a function of the Mach number only.
Effect of Taper on Screw-Thread Load Distribution
Authors: Stoeckly E. E. , Macke H. J.
Published: July 2022

The load distribution on the threads of bolts and nuts, made in the conventional constant-pitch manner and with tapered threads, was determined experimentally and theoretically. The results indicate that substantial improvement, in the order of 2 to 1, in thread load distribution can be made by tapering the thread of either the bolt or nut properly. Material improvement in bolting strength is obtained in applications that normally are conducive to little plastic flow and thus liable to result in brittle fractures, such as are encountered with dynamic loads or static loads at elevated temperatures. Ten years of operational experience on high-temperature high-pressure turbine bolting is cited to substantiate indicated improvements.
On the Automatic Control of Generalized Passive Systems
Authors: Chien Kun Li , Hrones J. A. , Reswick J. B.
Published: July 2022

The dynamic behavior of a multiple-capacity passive system is compared to that of a single-capacity system of appropriate “time constant with a finite time delay.” Such a comparison indicates that the latter system reproduces the dynamic behavior of the multiple-capacity system with sufficient accuracy for most engineering purposes. This fact makes it possible to characterize such systems by a single parameter, the ratio of the time constant (L) of the single-capacity system to the delay (D). Values of the control constants for various degrees of stability are plotted against this ratio (L/D) for proportional, proportional-plus-integral, proportional-plus-integral-plus-derivative type regulators. An electronic analog computer was used in obtaining the data.
Supervisory Instruments for Power-Generating Equipment—Application and Interpretation of Records
Authors: Stewart E. Y. , Reynolds J. H.
Published: July 2022

The proper application and use of turbine supervisory instruments is becoming more important owing to centralization of controls at remote points from the power-generating equipment and also the growing trend of power companies to quick-start their machines. Equipment is available to record turbine conditions in terms of shell and differential expansion, speed and camshaft position, bearing vibration, and shaft eccentricity. A description of shell and differential-expansion recording equipment is included. The value of the instruments depends upon the proper interpretation of the records. A feature of the paper is a discussion of a number of case examples in which mechanical trouble in the turbine or generator was detected by the instruments.
Analysis of Some Corrosion Problems in Petroleum Refineries
Authors: Mason J. F.
Published: July 2022

Over the past 25 years the Corrosion Engineering Section of the Development and Research Department of the author’s company has co-operated with the petroleum industry in analyzing corrosion problems encountered in refineries and in running spool tests to determine the most suitable and economical materials that might be used in specific applications. It is the purpose of this paper to present 15 actual corrosion problems that have been submitted for consideration and to show the steps taken to analyze them in the light of our practical experience and available test data obtained under the same or similar conditions. In some cases, where the problems were not readily solvable, based on available information, it was necessary to resort to the installation of spool-type specimen holders in the operating equipment to determine the relative suitability of various metals and alloys under actual service conditions. From the nature of the problems, it is indicated that Type 502 stainless steel is a highly acceptable and reasonably economical material as a replacement for mild steel except in instances where mineral acids or chlorides may be present as well as highly alkaline solutions at elevated temperatures. Under the latter conditions, the trend is toward the use of more highly alloyed materials such as Monel and nickel together with the copper-base alloys like 70-30 cupronickel, Admiralty metal, and Muntz metal.
Some Theoretical Aerodynamic Investigations of Impellers in Radial- and Mixed-Flow Centrifugal Compressors
Authors: Stanitz J. D.
Published: July 2022

The purpose of this paper is to present the numerical results of several theoretical, aerodynamic investigations of impellers in radial and mixed-flow centrifugal compressors and to discuss the significance of these results with respect to improved compressor performance. The solutions are not intended to supply specific design information but rather to help create a general understanding and awareness of the flow conditions in impellers of centrifugal compressors. The paper is given in two parts. In Part 1 two-dimensional relaxation solutions for compressible and incompressible fluids are presented for flow with axial symmetry (two solutions) and for flow between blades on surfaces of revolution about the axis of the impeller (eight solutions). The effects of variations in the following design and operating conditions of the impeller are investigated: (a) Compressor flow rate, (b) impeller-tip speed, (c) number of blades, and (d) blade curvature on flow surfaces of revolution. The numerical results are presented in plots of the streamlines, constant-velocity or Mach number lines, and constant static-pressure lines. In Part 2 three approximate methods of solution are presented which can be used for relatively rapid analysis of compressible flow between blades on flow surfaces of revolution.
Research in Exhaust Manifolds
Authors: Schweitzer P. H.
Published: July 2022

Over a period of four years, with the aid of the Office of Naval Research, the author has investigated the effect of the exhaust manifold on engine performance, particularly in two-stroke-cycle multicylinder engines. Some aspirator-type manifolds create suction rather than back pressure and result in scavenging-air flows that are greater than obtainable not only with conventional manifolds but even with no manifolds at all.
Station Design With Cyclone-Fired Steam Generators
Authors: Schroeder H. C. , Strasser R. J.
Published: July 2022

The need for finding better methods of burning Central Illinois coal led to the cyclone-furnace development. Sufficient operating experience has been gained since the first cyclone-fired steam generator was installed, as well as with numerous installations of recent years. Station design for cyclone-fired steam generators is treated in this paper as well as engineering design features of the installations now in operation. Consideration is also given to units in process of design and construction.
Effect of Velocity on Tensile Impact Properties of Polymethyl Methacrylate
Authors: Maxwell Bryce , Harrington J. P.
Published: July 2022

The history of impact testing of plastics is reviewed and the current theories of impact resistance are discussed. The effect of velocity on the energy absorbed by polymethyl methacrylate at various temperatures has been studied with the aid of two new testing machines. The results are interpreted in terms of the classical theories of mechanics of materials and the current theories of the rheology of high polymers. It is concluded that there are two distinct critical velocities of straining in this material—the lower one corresponding to the relaxation of the bonds restraining chain-chain slipping and the higher one corresponding to the relaxation of the secondary bonds involved in chain uncoiling. Both of these relaxations are temperature dependent—the lower one to a slight extent and the upper one to a marked extent. Above the two critical velocities the response of the material is purely elastic. A method of calculating the energy to break at rates of straining above the second critical velocity from the slow-rate stress-strain curves is demonstrated.
The Development and Implementation of a Generation Program on the American Gas and Electric Company System: 2—Fuel Supply
Authors: Sporn Philip , Kammer H. A.
Published: July 2022

This paper discusses the engineering and economics of fuel supply for the generating plants of the American Gas and Electric Company System, and in particular the fuel supply for two new plants—Kanawha River of Appalachian Electric Power Company, and Muskingum River of The Ohio Power Company. The importance of adequately planning fuel supply for a large power system is stressed, and the fundamental considerations of adequacy of supply, reliability, characteristics of supply, coal storage, and transportation are discussed with reference to the System characteristics, and with special emphasis on the development of the fuel supply for the two new plants.
Hysteresis of Shaft Materials in Torsion
Authors: Welch W. P. , Cametti B.
Published: July 2022

Static determinations of hysteresis of typical shaft materials in torsion show that the values are low for high-quality materials in unidirectional loading after several cycles of loading up to a shear-stress amplitude of 24,000 psi. For reversed loading, the hysteresis becomes several times larger and may be of significance in accurate torque-weighing devices. The measured hysteresis in a tubular specimen had values 3 to 4 times that for a solid specimen. Two nonmagnetic materials displayed very low values of hysteresis. The apparatus developed for this investigation had sensitivity sufficient to measure displacement changes of 0.002 per cent of the full-load deflection, and was designed to eliminate errors due to temperature changes, extraneous loads, and external vibration.
On the Solution of the Reynolds Equation for Slider-Bearing Lubrication—I
Authors: Charnes A. , Saibel E.
Published: July 2022

An exact solution is developed for the Reynolds equation in the hydrodynamical theory of slider-bearing lubrication with side leakage for film thickness varying exponentially. This solution is in the form of a rapidly convergent series from which calculations for the pressure distribution, total bearing load, and center of pressure may be made rapidly for all values of the parameter concerned. The results are in close agreement with those which have been obtained for the plane slider bearing by cumbersome methods, and it is proposed not only to use the present solution for the plane case, but also to show the design possibilities for a much wider variety of shapes by using various portions of exponential curves.
Basic Difficulties in Pulsating-Flow Metering
Authors: Deschere A. R.
Published: July 2022

Practically all research work in the field of flow metering has been devoted to a development of devices for obtaining an average of the square root of the pressure differential, and means for preventing distortion of the pressure transmission in the lines connecting the primary to the secondary part of the meter. The author shows that, in measurement of severely unsteady flow, these may not be the most important factors, but rather that the primary element itself does not give a response in this type of flow which can be interpreted correctly by the usual steady flow-metering methods.
Progress Report on the Study of Supercompressibility Factors for Natural Gases
Authors: Zimmerman R. H. , Beitler S. R.
Published: July 2022

A report is given on the present status of an evaluation of supercompressibility factors of natural gases. The aim of the research work is an attempt to establish an accurate method for the prediction of these factors within the pressure range 0 to 4000 psi and in terms of gas properties generally known or conveniently determined. The working method used to predict supercompressibility factors is based on the method proposed by Dunkle in 1944. Results of the method are compared with supercompressibility factors experimentally determined on the Burnett deviation apparatus.
Heat Transfer by Gas Conduction and Radiation in Fibrous Insulations
Authors: Verschoor J. D. , Greebler Paul
Published: July 2022

Thermal conductivity measurements were made on samples of an experimental glass fibrous insulation ranging in density from 0.5 to 8.4 pcf. Tests were carried out at atmospheric pressure with four different gases in the insulation samples, and the thermal conductivity with air was studied over a pressure range of 1 micron to 760 mm of Hg. Gas conduction is the most important mechanism of heat transfer. A theory of gas conduction in fibrous insulations was developed, and agrees well with experimental results. Theoretical considerations of heat transfer by radiation were confirmed by the experimental thermal conductivity values at low pressures. Methods are discussed of producing considerable reduction in the thermal conductivity of fibrous insulations.
Heat Transfer and Pressure Drop for Turbulent Flow of Air-Water Mixtures in a Horizontal Pipe
Authors: Johnson H. A. , Abou-Sabe A. H.
Published: July 2022

The static pressure drop and heat transfer for two-phase, two-component flow of air and water were measured for flow in a horizontal 15-ft length of 1-in. 16-gage brass tubing. Flow rates include the range of 1000 to 15,000 lb per hr for the water and 0 to 200 lb per hr for the air. Tentative correlations are presented from which prediction of pressure drop and heat transfer may be made under restricted flow conditions.
Contributions to Hydraulic Control: 2—Transient-Flow Forces and Valve Instability
Authors: Lee Shih-Ying , Blackburn J. F.
Published: July 2022

An outline is presented of a theory of a transient force which is one likely cause of oscillation of control valves, with supporting experimental evidence and methods of eliminating it.
Tool Forces and Tool-Chip Adhesion in the Machining of Nodular Cast Iron
Authors: Trigger K. J. , Zylstra L. B. , Chao B. T.
Published: July 2022

This paper presents the results of an investigation on the machining characteristics of nodular cast iron in both the as-cast and the annealed conditions. Tool forces, cutting temperatures, and tool-chip contact areas are compared for different grades of cemented-carbide tools. An adhesion phenomenon observed with this material provides evidence in support of the oxide-film theory and provides an explanation for some of the differences in wearing qualities of cemented-carbide tools.
A Comparison of Parameters for the Machining of Gray Cast Iron
Authors: Colwell L. V. , Holmes H. J. , Rote F. B.
Published: July 2022

This investigation was designed to compare several types of data as parameters for predicting cutting speeds for gray iron. A series of eleven irons, representing ranges of alloys, ferrite, graphite, and mechanical properties was used in the study. Cutting forces, power, and energy were determined from drilling and milling tests, and cutting speed - tool life lines were determined for each of the irons. Finally, correlations were attempted between the cutting speed (V20) for a 20-min tool life, and all other available types of information. The net result of this approach was a comparison of the relative reliability of the different types of data. This comparison showed that combined carbon, microhardness, and the nucleation or graphitizing tendency hold the greatest promise of developing into reliable parameters, while Brinell hardness, tensile strength, drilling forces, and milling power show little promise of providing useful information. This study was preliminary in nature and was intended only as a screening process for narrowing down the field for future investigations. Consequently, the correlations between cutting speed and combined carbon, microhardness, and nucleation tendency are undeveloped, and applications should not be attempted without further investigation.
On the Accuracy of Extrapolated Creep-Test Relations for Plexiglas Subjected to Various Stresses
Authors: Marin Joseph , Pao Yoh-Han
Published: July 2022

Most creep-time relations for materials are obtained for short periods of time—usually for 1000 hr or about 40 days. In many applications, however, the life of the member is much greater than 1000 hr. In the design of these members, therefore, it is necessary to provide for creep deformations which cover periods of time much greater than 40 days. To do this, it is common practice to obtain a stress-creep-time empirical relation based on 1000-hr test data, and to extrapolate these relations to periods of time representing the service life of the part. The purpose of this paper is to determine the accuracy of this extrapolation. This is accomplished by comparing the extrapolated tension and compression creep-time relations based on 1000-hr test data with actual 10,000-hr creep-test data. Long-time creep-test data also were obtained for pure bending and pure torsion. These creep-time relations were compared with theoretical values based on empirical relations for 1000-hr tension and compression creep data. For the relations used and for the material tested, it was found that the extrapolated values gave good engineering approximations to the actual values.
Heat Transfer From Spheres to a Rarefied Gas in Supersonic Flow
Authors: Drake R. M. , Backer G. H.
Published: July 2022

An approximate analysis is presented for the prediction of the over-all average heat-transfer coefficients from spheres to air in the transition-flow region, that region wherein the mean free molecular path is small but not negligible when compared with the sphere diameter. The analysis is made on the basis of a simplified flow field and the utilization of the continuum formulation of the energy equation with the rarefaction effects being accounted for entirely in the boundary conditions. The results of the analysis are compared with experimental heat-transfer data from spheres to air in the transition-flow region, with heat-transfer data from spheres to air in the continuum-flow region, and with the calculated results of heat transfer from spheres in the free molecule-flow region. Experimental free-stream recovery factors are presented for spheres. Significant flow parameters and flow-region limits for the transition region are discussed.
Friction Surfaces for Spin-Up Simulation in Landing-Gear Drop Tests
Authors: Drake D. W.
Published: July 2022

Current procedures for drop testing of landing gears entail the simulation of wheel spin-up. The use of a fixed reaction surface in conjunction with spinning wheels in the drop tower introduces friction conditions between the tire and reaction surface that do not permit direct use of airport surfaces such as concrete. For this reason the “coefficients of friction” of a number of reaction surfaces have been evaluated and their value for spin-up simulation is discussed.
The Mean Flow in Kaplan Turbines
Authors: Meyer R. E.
Published: July 2022

All theories now in use for the design of the bladings of Kaplan turbines and pumps are based on the assumptions that the fluid moves on concentric cylinders and that no trailing vorticity is shed off the blading. Approximate corrections are here found arising from the fact that the flow does not, in practice, satisfy these assumptions. These corrections are the more important the smaller the ratio of hub diameter to tip diameter. An approximation to them is found from investigation of the axially symmetrical mean flow in the rotor, which is obtained when the velocity components at any point are replaced by their mean values with respect to the angular co-ordinate. This approximation is the more accurate the smaller the pitch-chord ratio. It is found that the three-dimensional effects in the flow are due to the transverse component of the vorticity (“ring vorticity”). Formulas for the velocity components induced by it are given. Two distinct problems arise in connection with the design of a Kaplan blading, viz., (a) to find the shape of the blade and the pressure distribution for a prescribed load distribution, under the optimum working condition, and (b) to find the performance and pressure distribution for a prescribed blade shape, after a change of pitch. The theory applies also to multistage axial-flow turbomachines where the mean velocity is not too high for knowledge of the incompressible flow to be of interest.
Instrumentation for Axial-Flow-Compressor Research
Authors: Meyer C. A. , Benedict R. P.
Published: July 2022

A discussion of many of the air-flow instruments currently used in compressor research is given. A history of the development of some of the instruments is presented together with the reasons for adopting the present designs. Optimum dimensions, based on test data, are included for claw probes, cylindrical probes, spherical probes, and averaging probes. Errors encountered in temperature measurement by means of thermocouples are reviewed, and methods for reducing these errors are suggested. A discussion of traversers is also included.
A Study of Heat Developed in Cylindrical Grinding
Authors: McKee R. E. , Moore R. S. , Boston O. W.
Published: July 2022

This paper, the fourth in a series on cylindrical grinding, presents some of the results of an investigation of the grinding process with particular reference to the influence of the grain size of a grinding wheel and type of grinding compound used on certain criteria; such as volume of metal removed per unit of wheel wear, unit net horsepower, surface finish, grinding rating, temperature increase in the workpiece surface, temperature increase in the grinding compound, and possible injury to the structure of the metal.
An Analytical Evaluation of Metal-Cutting Temperatures
Authors: Trigger K. J. , Chao B. T.
Published: July 2022

This paper presents an analytical method for the determination of metal-cutting temperatures. The average tool-chip interface temperature is calculated by considering the mechanism of heat generation during metal-cutting operations in which a type 2 chip is formed. The analytical results agree well with those obtained by test methods, and the theoretical analysis has also yielded some important physical quantities and measurements which affect cutting temperatures.
Dynamic Shear Properties of Rubberlike Polymers
Authors: Hopkins I. L.
Published: July 2022

A simple apparatus for determining the dynamic properties of elastomers in shear at audio frequencies is appraised. Typical values of shear modulus and viscosity for several elastomers are given, both at room conditions and at 150 F. The frequencies of test range from 100 to 5250 cycles per second, the shear moduli from 0.5 × 106 to 480 × 106 dynes per sq cm and the viscosities from 20 to 75,000 poises.
Joints for High-Pressure High-Temperature Piping
Authors: Carlson I. H. , Black W. S.
Published: July 2022

This paper outlines briefly the difficult problem of obtaining leakproof joints for high-pressure high-temperature piping. It includes the results obtained from an extensive test on three full-sized joints for connecting ferritic-alloy main steam piping to austenitic-alloy turbine equipment of 150,000-kw capacity. The scope of the tests was limited by the amount of steam available, but the information secured should be of value to others having similar problems. It is hoped that others having experience or knowledge in this field will contribute additional information concerning this problem which is important to the continued progress of the power industry.
Dynamic Loading of Chain Drives
Authors: Stamets W. K.
Published: July 2022

This paper describes the dynamic loads sustained by power chain when running at high speeds. Conditions for least destructive fatigue loading are set forth, and a formula for optimum chain speed is derived. Dynamic load tests on silent chain are reported in which the loading was measured by means of a special strain gage of the author’s design. The tests prove the loading postulated in the first part of the paper, and the conclusions indicate a new approach to chain-drive layouts for power transmission.
Effect of Molecular Weight of Entrained Fluid on the Performance of Steam-Jet Ejectors
Authors: Holton W. C.
Published: July 2022

A program of research sponsored by the Heat Exchange Institute involved pumping 13 pure gases and 12 mixtures of gases with small commercial single and two-stage steam-jet ejectors supplied by two manufacturers. Results were calculated in terms of “air equivalent” or “entrainment ratio,” which is the ratio of the flow rate of gas to that of air under similar conditions. Entrainment ratios were found to be a function of the molecular weight of the gases handled and were plotted as a smooth curve, which is independent of pressure, design characteristics of ejectors, and is applicable to mixture of gases. It is concluded that the curve may be used to predict results obtainable with any ejector system.
Problems Relating to Operation, Maintenance, and Chemical Control of Cooling Towers for Steam-Electric Generating Stations
Authors: Estcourt V. F.
Published: July 2022

In a generating station, cooling-tower performance must be considered not only in terms of heat dissipation but also in relation to the over-all results obtainable with a particular combination of tower, condenser, and turbine. There is an important relationship between turbine leaving losses and the optimum tower size. This approach to the subject involves not only the economic size of the tower but also certain operating problems which vitally affect the station heat rate. The problem of condenser-tube scale deposits is more likely to become critical where cooling towers are used, because of higher cooling-water temperatures. Successful results are described in the use of threshold treatment of cooling-tower water with stabilized phosphate in combination with sulphur burning for keeping condensers free of scale deposits. The problems of recirculation, fan-blade failures, and noise nuisance are also discussed.
Deterioration of Wood in Cooling Towers
Authors: Baechler R. H. , Richards C. A.
Published: July 2022

The premature deterioration of wood in cooling towers has received considerable attention during the past several years. Although the number of towers so affected appears to be rather small compared with the total number in use, premature deterioration nevertheless deserves serious study. The owner of a tower needing expensive repairs after only a relatively short period of use can draw small comfort from the fact that wood in most cooling towers gives satisfactory service. Furthermore, an upward trend in the percentage of towers affected must be recognized as a distinct possibility, making the need for corrective measures even greater than is indicated by past experience. The preliminary investigations described in this paper were intended to throw some light on a few of the many questions that have arisen regarding wood failure in cooling towers. A brief discussion of the nature of wood, the kinds of deterioration it may undergo, and the conditions to which it is exposed in a cooling tower are given.
The Nonsteady-State Load-Supporting Capacity of Fluid Wedge-Shaped Films
Authors: Gatcombe Ernest K.
Published: July 2022

A study is presented of the thickness and load-supporting capacity of fluid wedge-shaped films entrapped between the peripheral surfaces of rotating circular disks which are vibrated transversely, causing the wedge-shaped film to become alternately thin, then thick at moderately high frequencies. This nonsteady-state loading of the wedge is accomplished by mounting circular disks, Fig. 1, on parallel shafts with centers at d and d’, then transversely vibrating the beam which supports the complete lower-shaft assembly, consisting of bearings, bearing hangers, etc., see Fig. 4. Part 1 (see Fig. 1) is devoted to a theoretical analysis of the thickness and load-steady-state problem has yielded solutions which have not been obtainable by theoretical studies, except for cases involving assumptions which greatly alter the true results. It is found that the normal approach vibratory motion of the surfaces bounding the film is responsible for a much greater part of its load-supporting action than is the steady-state rotational motion.
Dynamic Force Reactions in Double-Ported Control Valves
Authors: King C. F. , Brockett G. F.
Published: July 2022

Torsional force reactions on V-port inner valves, and vertical force reactions on plug-type inner valves in double-ported control-valve bodies are of sufficient magnitude to cause concern if pressure drop is high. These forces are proportional to the mass velocity of the flowing fluid. It is possible to design inner valves so that these forces will be reduced to a point where they are not objectionable.
The Development of a Design of Smokeless Stove for Bituminous Coal
Authors: Landry B. A. , Sherman R. A.
Published: July 2022

This paper presents an account of an extended systematic investigation which resulted in the development of a method for burning bituminous coals in nonmechanical hand-fired heaters or stoves with substantially smokeless operation. The research was sponsored by Bituminous Coal Research, Inc., and a group of stove manufacturers. An experimental investigation of the three principles of combustion in fuel beds led to the adoption of the cross-feed principle. The design of a special grate and the research to prevent puffing, a difficulty often encountered with magazine heaters, are described. The principles of a calorimeter room in which the output of a space heater can be directly measured are presented. Data given show the thermal efficiency of a manufacturer’s model of the heater, which had an output of 41,000 Btu per hr, to be 65 per cent.
Report on Graphitization Studies on High-Temperature Welded Piping of The Philadelphia Electric Company
Authors: Abele J. B. , White A. E.
Published: July 2022

Summaries of the work which has been done by and for the Philadelphia Electric Company in ascertaining the degree of graphitization in the piping system in the Chester, Schuylkill, and Richmond Stations since the fall of 1946, are reported in this paper. The results of a fullsize pipe tension test on a graphitized weld section are reported. Solution treatment for removal of graphitization is described with some physical test results.
Steam-Electric Power Expansion in Southern California
Authors: Chadwick W. L.
Published: July 2022

This paper presents the background of the postwar expansion of steam power in Southern California, the requirements of the area served, a brief discussion of some of the war and postwar influences bearing upon power needs, the disposition of the new generation, the design trends in the area, and the influences bearing thereon. A description is given of the major features of the Redondo Steam Station of the Southern California Edison Company.
Combination of Heat Sources and Sinks by the Method of Superposition
Authors: Bridgers F. H.
Published: July 2022

A superposition method is proposed whereby the temperature pattern around a single buried heat source at a given temperature is used to arrive at the pattern obtained when several heat sources at the same temperature are placed at any distance apart. An equation is derived to give the “strength ratio,” which is defined as the ratio of heat dissipated by one of a series of buried heat sources of equal temperature to the heat dissipated by a single heat source at the same temperature. This equation is plotted for a specific case to show the “strength ratio” as a function of heat-source spacing. Experimental temperature-distribution patterns around a heated tube buried in a box of sand are shown for the center tube of a group of three tubes. Although the proposed superposition method is subject to an inherent error, which may be severe at very close spacing of heat sources, the agreement between experimental and calculated results for the cases investigated in this work is good.
Chemical Treatment, Demineralization, or Evaporation for Make-Up in High-Pressure By-Product Steam Plants
Authors: Yoder J. D. , Webb W. L. , Baumeister T.
Published: July 2022

The increased power production obtained by exhausting high-pressure turbines directly to process rather than to coils of evaporators, which in turn produce process steam, is demonstrated. Typical heat balances are presented for systems employing evaporated make-up to the closed cycle and for 100 per cent make-up cycles using water treatments consisting of (a) silica removal and sodium-zeolite softening, and (b) demineralization and silica absorption. Performance data and costs are given for both evaporated make-up and 100 per cent treated make-up 1400-psi cycles at the Deepwater Operating Company’s station.
Continuous Gasification of Pulverized Coal With Oxygen and Steam by the Vortex Principle
Authors: Perry H. , Corey R. C. , Elliott M. A.
Published: July 2022

This progress report presents the preliminary results of the gasification of pulverized coal by steam-oxygen mixtures in a vortex reactor. The basic principles of reactor design, and an illustrative example of their application are given. A method of calculating the composition of the gas produced in this reactor is presented and has been checked experimentally. The carbon conversion and the limits of operation have been found to be closely related to the type and uniformity of the coal distribution. A method of improving the operation of the equipment and the quality of the gas by a change in the type of coal distributor appears to be promising.
A Perforated-Plate Heat Exchanger
Authors: McMahon H. O. , Bowen R. J. , Bleyle G. A.
Published: July 2022

Performance data of heat transfer and flow resistance are presented for the continuous heating of air in several experimental variations of a new type of perforated-plate heat exchanger. These exchangers consisted of sections built up by stacking multiple units of a perforated aluminum plate and a neoprene gasket, to form parallel channels perpendicular to the plate faces. Tests were conducted by causing air to flow countercurrently through these passages. The effects of hole diameter, plate thickness, and gasket thickness (or plate separation) are indicated. Results are presented jointly in the form of a pressure-drop efficiency factor versus Reynolds number for portions of the range between 800 and 4300.