bluuebunny/crossref_metadata_2025_split huggingface dataset:
A New Approach to Metal-Forming Problems: Experimental Stress Analysis for a Tubular Extrusion
Authors: Thomsen E. G. 
Published: July 2022

Abstract
An incremental inverted extrusion process was used to obtain magnitude and direction of particle velocities in a billet during the pressing of a tubular product. The material chosen was commercially pure lead which can be hot-worked at room temperature and is believed to be a representative species of hot-worked metals. The reported graphical technique using experimental data is applied to a problem presently insolvable by analytical methods. It was found that both axial stresses and mean pressures in the region of the die were higher on the extrusion axis and near the cylinder wall than in the central region of the billet. This stress distribution is appreciably different from that of a solid extrusion for the same reduction in area. The present solution is a distinct advance in the direction of understanding three-dimensional metal-forming problems.
Bagasse-Burning in the Mexican Sugar Industry
Authors: de Lorenzi Otto 
Published: July 2022

Abstract
Bagasse is the principal source of heat for the production of raw sugar. Early furnace designs were satisfactory from the standpoint of operation and steam output during the period when labor was plentiful and this by-product fuel was assigned little or no value. Rising costs of fuel, equipment, repairs, and wages, however, have altered this picture materially. Older plants consisted in a multiplicity of small boilers with refractory hearth-type furnaces. Operating efficiency was low, and steam output dropped during long periodic hearth-cleaning periods. These designs are definitely outmoded through the rapid advances which have been made during the past 10 years. Newer designs of steam-generating units now incorporate spreader stokers, water-cooled furnaces, bent-tube boilers, superheaters, air heaters, and bagacillo-return systems. They have more flexibility, greater capacity, higher efficiency, and are less subject to operational interruption. Many units of this type have now been in operation for considerable periods of time in practically all of the world’s raw-sugar-producing areas. It is the purpose of this paper to discuss, primarily, the operating characteristics of this new design as experienced with installations in Mexico. Comparative data also will be presented to stress normal operating differences between hearth-type and spreader-fired unit.
The Combustion-Efficiency Problem of the Turbojet at High Altitude
Authors: Olson W. T. , Childs J. H. , Jonash E. R. 
Published: July 2022

Abstract
This paper discusses NACA research on the single problem of combustion efficiency of turbojet engines at high altitudes. Representative results of investigations with turbojet combustors are presented to illustrate the trends obtained with the following categories of variables: (a) Combustor operating variables, (b) combustor design variables, and (c) fuel variables. The data indicate that as the environment of the combustor becomes one of low pressure and low temperature at high altitude, low combustion efficiencies and limited values of obtainable temperature rise are encountered. Increased cross-sectional area of combustor for a given weight flow of air decreased velocities and facilitated high combustion efficiency at altitude. For the design of the liner, increased volume in the flame zone and gradual admission of the air into the combustion space were shown to aid combustion by helping to provide that localized fuel-air mixtures of correct composition exist sufficiently long for ignition and combustion to occur. For high combustion efficiency to occur, all of the fuel must be involved in this manner, and it was shown that the combustor design, the fuel injection, and the fuel volatility must be matched if optimum combustion efficiency is to be achieved. Further, it was shown that, for a given combustor, fuel injector, and fuel volatility, fuels of higher flame speed and/or lower ignition temperatures gave higher combustion efficiency at high-altitude operating conditions.
The Grinding of Titanium Alloys
Authors: Yang C. T. , Shaw M. C. 
Published: July 2022

Abstract
When titanium is ground under conventional conditions the rate of wheel wear is abnormally high and the finish produced is poor. Improvement in surface finish accompanies a decrease in wheel-wear rate. A study of the influence of a wide variety of operating and grinding-wheel variables reveals the most important quantities to be grinding-wheel speed, type of abrasive, and grinding fluid. When a wheel speed of 1500 to 2000 fpm is used with a suitable fluid and a white-aluminum-oxide wheel of conventional hardness, grain size, and bonding, greatly improved results are obtained. All of the observations that have been made can be explained in terms of the assumption that bonding between titanium chips and abrasive grains is of major importance. While most of the experiments and discussion are centered around the surface-grinding operation, cylindrical grinding and the cut-off operations also are considered.
Working-Stress Criteria for Nuclear Power Plants
Authors: Langer B. F. 
Published: July 2022

Abstract
There are two respects in which strength calculations for nuclear-power-plant components may differ from calculations made for conventional heat-power or process equipment. One is the greater importance of thermal stresses resulting from the generation of heat inside the material of the structure, and the other is the frequent use of unfamiliar materials. In this paper a method is proposed for combining the stresses produced by fluid pressure with those produced by thermal gradients in order to arrive at a practical estimate of the factor of safety in a structure such as a pressure vessel. Because of the relaxation of thermal stress it is possible to show that certain operating conditions are really safe even though a simple addition of pressure stress and thermal stress gives too high a value. A discussion is given of the relative importance in reactor design of such physical properties as ductility, creep, endurance limit, creep-rupture strength, impact strength, and notch sensitivity.
An Investigation of the Melting of Bodies Due to Aerodynamic Heating
Authors: McLellan C. H. 
Published: July 2022

Abstract
Various approaches to the aerodynamic heating problem of bodies re-entering the atmosphere are considered briefly. One approach to this problem is to allow the heat to be absorbed by the body. At very high supersonic velocities, part of the body can be expected to melt. An analysis of a high-density conical-nosed vehicle entering the atmosphere at a speed of 20,200 fps showed that, in addition to the melting at the tip of the cone, the temperature gradients through the skin become very large and, under some conditions, surface melting would occur on the cone as well. Since very little was known about the melting of bodies due to aerodynamic heating, an exploratory investigation was made in the Langley 11-Inch Hypersonic Tunnel. The results of melting tests of several bodies made of a low-melting-temperature alloy are discussed.
Problems in the Design of Aircraft Subjected to High Temperature
Authors: Steinbacher F. R. , Young Louis 
Published: July 2022

Abstract
Design problems associated with the high temperatures of supersonic flight are discussed. Factors, affecting choice of materials, significant changes in methods of analysis and allowable loads, and the need for a new safety criterion, are covered. The importance of the various factors influencing high-temperature design are evaluated and some indication of the direction, future research should take, is given.
Important Considerations in the Use of the Wind Tunnel for Pollution Studies of Power Plants
Authors: Strom G. H. , Halitsky James 
Published: July 2022

Abstract
The theoretical bases for wind-tunnel experiments on stack-gas pollution by power plants are examined and important variables and scale factors are presented. Test results are presented to show some effects of these variables. The test procedure now in use at the New York University 3½ by 7-ft wind tunnel is described. Correlation with limited field data is presented with a discussion on accuracy of wind-tunnel experiments.
The Design of the Expanding-Shoe Friction Clutch
Authors: Cohen M. J. 
Published: July 2022

Abstract
The following development gives a complete and exact treatment of the problem of the design of friction clutches of the expanding-shoe variety. The method followed is one which, ab initio, takes all the relevant parameters of the clutch, such as dimensions, elastic properties, and the forces-moment system to be arbitrary and then proceeds to relate them by a set of equations that illustrate the final equilibrium of the system. From the three basic equations derived, a simple and very rapid design technique is evolved which can be used reliably by technicians for the design of one such clutch to transmit a required torque. Section 10 incorporates the complete technique of design and can be interpreted simply without reference to the theoretical considerations leading to it in the preceding sections.
The Effect of Pulse Shape on Simple Systems Under Impulsive Loading
Authors: Crede C. E. 
Published: July 2022

Abstract
This paper proposes modified parameters for presenting “shock spectra” for elastic systems acted upon by acceleration pulses. It is shown that the ratio of maximum response acceleration to maximum acceleration of the pulse is a function of the pulse shape. By introducing a parameter which includes velocity change of the pulse and the natural frequency of the elastic system, in place of maximum acceleration of the pulse, the influence of pulse shape on the spectrum is reduced materially. The significance of the spectrum for lightly damped systems is considered where failure may result from fatigue after many cycles of stress reversal induced by a single pulse.
Impact and Longitudinal Wave Transmission
Authors: Smith E. A. L. 
Published: July 2022

Abstract
The necessary formulas for a numerical method of calculation are derived without the use of calculus or other advanced mathematics; an illustrative problem is solved in complete detail; eight different types of impact are discussed; methods are given for taking account of friction, damping, coefficient of restitution, plastic flow, and gravity; branched systems are discussed briefly; methods are given for checking the calculated results.
The Ultrasonic Measurement of Hydraulic Turbine Discharge
Authors: Swengel R. C. , Hess W. B. , Waldorf S. K. 
Published: July 2022

Abstract
To obtain the basic discharge data necessary for efficient hydroelectric operation, a new ultrasonic flowmeter has been developed and applied to the measurement of flow in large water passages. During the development period, extensive tests under varied conditions of flow were made in a passage, 5 in. × 9 in., using a weighing tank as the absolute standard. Accuracies of 1 per cent or less were achieved regularly with appreciably turbulent and nonuniform flow distributions, using river water of varying turbidity. Installation in a turbine intake, 16 ft × 25 ft, has demonstrated the practicality of the method and equipment.
Recent Investigations of the Mechanics of Cavitation and Cavitation Damage
Authors: Knapp Robert T. 
Published: July 2022

Abstract
This paper describes water-tunnel investigations into the mechanics of “fixed”-type cavitation and into the probable mechanism through which this type causes material damage. High-speed motion pictures were used to study the cavity mechanics, and indications of the damage pattern were obtained by measuring the pitting rate on soft aluminum test specimens. Information was obtained on the frequency and intensity of the damaging blows, the distribution of damage in relation to the area covered by the cavitation, and the variation of the intensity of cavitation with velocity.
On the Mechanism of Cavitation Damage
Authors: Plesset M. S. , Ellis A. T. 
Published: July 2022

Abstract
A new method for producing cavitation damage in the laboratory is described in which the test specimen has no mechanical accelerations applied to it in contrast with the conventional magnetostriction device. Alternating pressures are generated in the water over the specimen by exciting a resonance in the “water cavity.” By this means the effects of cavitation have been studied for a variety of materials. Photomicrographs have been taken of several ordinary (polycrystalline) specimens and also of zinc monocrystals. The zinc monocrystal has been exposed to cavitation damage on its basal plane and also on its twinning plane. X-ray analyses have been made of polycrystalline specimens with various exposures to cavitation. The results show that plastic deformation occurs in the specimens so that the damage results from cold-work of the material which leads to fatigue and failure. A variety of materials has been exposed to intense cavitation for extended periods to get a relative determination of their resistance to cavitation damage. It is found that, roughly speaking, hard materials of high tensile strengths are the most resistant to damage. While this survey is not complete, it has been found that titanium 150-A and tungsten are the most resistant to damage of the materials tested. Cavitation-damage studies, which have been carried out in liquid toluene and in a helium atmosphere, show that chemical effects can be, at most, of secondary significance.
Turbulent Heat Transfer and Friction in the Entrance Regions of Smooth Passages
Authors: Deissler R. G. 
Published: July 2022

Abstract
The effect of various factors on the turbulent heat transfer and friction in the entrance regions of smooth passages is investigated analytically. The influence of Reynolds number, Prandtl number, initial velocity distribution, wall-boundary condition, passage shape, and of variable fluid properties is predicted. Integral heat-transfer and momentum equations are used for calculating the thicknesses of the thermal and flow boundary layers. The results indicate that approximately fully developed heat transfer and friction are, in general, attained in an entrance length less than 10 diameters. Substantial agreement between analysis and experiment was obtained for heat transfer to air in the entrance regions of tubes and parallel plates.
Chemical Cleaning in Central Stations
Authors: Cardwell P. H. 
Published: July 2022

Abstract
Chemical cleaning now has been applied to all equipment which contains scale and sludge deposits in central stations. A discussion is given of these various units along with a description of the different types of solvents employed. An explanation of certain types of corrosion is given. Improved acid corrosion inhibitors are now being used in order to give the necessary protection on stressed areas, on zones having dissimilar grain sizes, and on metals containing the Widmanstätten structure. Information is given as to the ferric-iron corrosion problem.
An Interferometric Study of the Boundary Layer on a Turbine Nozzle Blade
Authors: Faulders C. R. 
Published: July 2022

Abstract
The boundary layer on a turbine nozzle blade was investigated with an optical interferometer over a range of Reynolds numbers and subsonic downstream Mach numbers. The ratio of laminar boundary-layer thickness to distance downstream from the minimum pressure point on the suction side of the blade was found to be essentially a unique function of a length Reynolds number based on this distance. Thickness critical Reynolds numbers for transition increased, with throat Reynolds number, from 3000 to 9000 on the suction side and from 1200 to 3100 on the pressure side. A laminar velocity profile was computed from a density profile measured at a point of zero pressure gradient, and satisfactory agreement with theoretical profiles was obtained.
Natural Frequency of a Nonlinear System Subjected to a Nonmassive Load
Authors: Crede C. E. 
Published: July 2022

Abstract
This paper discusses a single-degree-of-freedom system with nonlinear elasticity such that the stiffness increases as the deflection increases. This stiffness increase, without a change in the mass, effects an increase in natural frequency. Graphical means are presented to evaluate the increase in natural frequency when the support for the system experiences a sustained constant acceleration.
Distribution of Shear-Zone Heat in Metal Cutting
Authors: Leone W. C. 
Published: July 2022

Abstract
The paper presents an expression for the fraction of thermal energy developed at the shear zone in orthogonal metal cutting which is conducted back into the workpiece. The shear-zone temperatures calculated using this expression are found to compare favorably with those measured indirectly by Trigger and with those calculated by use of Hahn’s inclined-source solution.
Discontinuous Chip Formation
Authors: Cook N. H. , Finnie Iain , Shaw M. C. 
Published: July 2022

Abstract
The extent of fracture in the chips in a metal-cutting operation varies from cracks that are just discernible under the microscope to complete discontinuity where the metal removed is in the form of discrete particles. The fracture that occurs in all of these cases is either of the ductile shear type (which predominates in metal cutting) or the brittle tensile type. The characteristics and causes of these two types of fracture are first discussed and then applied to the problem of chip fracture. The very limited fracture that occurs at the point of a tool in “continuous cutting” is held to be of the tensile type, and the role of tool sharpness in this connection is discussed. It is shown by means of motion pictures and dynamometer data that completely discontinuous chip formation is entirely different from that in continuous cutting, being better described as a periodic extrusion process rather than one of simple shear. In discontinuous cutting the friction between chip and tool is static rather than dynamic in nature. The normal stress on the shear plane, as influenced by rake angle or tool friction, is found to be an important variable in determining whether a chip will be continuous or discontinuous. Other variables of importance include the cutting speed, depth of cut, number, shape, size, and hardness of inclusions in the metal cut, and tool rigidity. The influence of these several variables with regard to chip discontinuity is discussed and a number of examples are presented to illustrate the principal points that are made.
The Elastic-Fluid Centripetal Turbine for High Specific Outputs
Authors: Birmann Rudolph 
Published: July 2022

Abstract
The radial inward-flow (or centripetal) turbine for elastic fluids has been the subject of theoretical and experimental investigation by the author for the past 25 years, during which time a number of applications were made by his Company to steam and gas turbines—applications for which the centripetal turbine was found to be distinctly superior to the axial-flow type. In so far as is known, no other manufacturer used this type of turbine until recently, when several companies applied it to the construction of small gas turbines, and coincidental therewith several technical papers were written expounding its virtues. Judging from these applications and the published material, it would appear that the greatest merit of the centripetal turbine—which lies in the fact that it can be designed for specific outputs far exceeding those of the axial-flow wheel—still remains unrecognized. In this paper it will be shown, by the presentation of drawings, photographs, test results, and numerical examples, that the centripetal turbine can be designed to handle larger flows and higher enthalpy drops at higher rpm with better efficiency and lower stresses than the axial-flow turbine, and that because very high specific outputs are thus made possible, it permits the solution of design problems which cannot be solved by the axial-flow wheel.
On the Analysis of Cutting-Tool Temperatures
Authors: Loewen E. G. , Shaw M. C. 
Published: July 2022

Abstract
In modern machine-tool practice, cutting temperatures are assuming increasing importance as cutting speeds and feeds are increased and new materials of construction are introduced. Although methods are available for determining experimentally the mean temperature on the tool face of a cutting tool, it is not possible to determine experimentally the influence of many of the variables influencing this temperature, or to measure conveniently its components. The analytical procedure to be followed in computing cutting temperatures is presented and illustrated by several examples. The relative importance of the several variables influencing tool-face temperatures is discussed and the variables of real significance are listed in order of importance. The only important thermal quantity of the system is the product of the thermal conductivity and the volume of specific heat of the workpiece. Analytical results are employed to explain the unusually high temperatures that are observed in machining titanium alloys.
Design of Steam Piping and Valves for 1100 F
Authors: Ritchings F. A. , Crocker Sabin 
Published: July 2022

Abstract
Results are available from extended research on the behavior of austenitic and ferritic steels in a steam atmosphere at 1100 F. Allowable stresses at temperatures up to 1110 F and higher have been assigned by code committees with respect to long-time strength as determined from creep and stress-to-rupture tests. Two large boiler-turbine units employing austenitic piping for 1100 F throttle steam temperature are being installed in 1953. Austenitic steels are definitely expensive, however, and alloying elements, particularly nickel and columbium, are in short supply. The present paper reviews existing data and speculates on whether low-alloy-content ferritic steels could be made to serve the purpose. Spot comparisons are made of the relative cost of austenitic and ferritic steel pipe of equivalent carrying capacity. (See Table 1 for identification of the austenitic and ferritic steels considered.)
Remarks on Film Condensation With Turbulent Flow
Authors: Seban R. A. 
Published: July 2022

Abstract
Analogy calculations of the Prandtl-Kármán type are applied to the film condensation of a pure substance on a vertical wall under such conditions that the flow in the condensate layer is turbulent. The results agree with Colburn’s predictions made by the use of his analogy, which predictions are in general agreement with the meager experimental data available. The present results are extended to condensates of low Prandtl number, such as molten metals, and, as has been demonstrated already for the case of flow in closed channels, the contribution of turbulence in this case is found to be small until high Reynolds numbers are attained. Results for the mean heat-transfer coefficient are presented for Prandtl numbers from 0 to 5 and for Reynolds numbers as high as 105.
The Work-Sampling Technique
Authors: Rowe A. J. 
Published: July 2022

Abstract
Many techniques currently are used for the measurement of factory work. These techniques include stop-watch studies, interruption studies, production studies, occurrence-type studies, predetermined elemental time systems (such as methods and time measurement), and work-sampling studies, (which often are called ratio-delay studies). Work sampling, as the name implies, is a statistical sampling procedure for obtaining information about industrial activities. The principles are well developed, since they are essentially the same as any other sampling technique. The purpose of this paper is to elaborate on the application of the basic principles to the measurement of factory activities.