bluuebunny/crossref_metadata_2025_split huggingface dataset:
Heat Transfer to Constant-Property Laminar Boundary-Layer Wedge Flows With Stepwise and Arbitrary Wall-Temperature Variation
Authors: Scesa Steve , Levy Solomon 
Published: July 2022

Abstract
The analysis for the determination of the heat transfer for bodies in constant-property two-dimensional laminar flow with a free-stream velocity variation as u1 = Kxm and a stepwise wall-temperature variation is presented. The general theory may be applied to a gas of any Prandtl number although numerical results have been computed herein for Prandtl numbers of 0.7 and 1 for the values of m equal to —1/13, 0, 1/9, 1/3, 1, and 4. The method of investigation is such that the temperature profile may be obtained if so desired. Results of local Nusselt number are compared with the more approximate investigations of Bond and Lighthill which indicate an increasing deviation as m increases or decreases from zero. However, comparison of the ratio of the local Nusselt number with a stepwise wall-temperature variation to the local Nusselt number for a constant wall temperature indicates good agreement with the results of Bond and Lighthill. Extension to the problem of an arbitrary wall-temperature variation is indicated. The theoretical investigation neglects the effect of heat generated by friction since this effect may be considered by superposition of proper solutions.
The Dynamics and Lubrication of a Miniature Turbine Rotor on Porous Bushings
Authors: Sines George 
Published: July 2022

Abstract
A miniature air turbine was designed to investigate the lubrication and dynamic action of the rotor shaft within the bearing clearance. An optical apparatus was used to observe the time-position history of the shaft. Several different mechanisms of lubrication were identified at various speeds; at higher speeds boundary lubrication may occur. Under certain conditions the shaft moves in a very irregular pattern characterized by low friction and long bearing life. The conditions for the onset of this motion are discussed.
On the Solution of the Reynolds Equation for Slider-Bearing Lubrication—VII: The Nonsteady-State Operation of Tilting-Pad Slider Bearings
Authors: Osterle F. , Charnes A. , Saibel E. 
Published: July 2022

Abstract
The Reynolds equation in hydrodynamic lubrication theory, modified to take into account nonsteady-state effects, is applied to the problem of the tilting-pad slider bearing subject to a sinusoidal pivot oscillation in the direction normal to the bearing surface. Relationships are developed giving the load-supporting capacity and coefficient of friction as functions of the amplitude and frequency of the oscillation.
Study of Cubic Characteristic Equation by Root-Locus Method
Authors: Chu Yaohan , Yeh V. C. M. 
Published: July 2022

Abstract
It is shown in this paper that all possible roots of a cubic characteristic equation lie on a portion of a hyperbola and of its axis. This hyperbola may be sketched readily from the values of the coefficients of the cubic equation. Hence the change of the roots of the cubic equation due to any change in its coefficients may be visualized. The discussion of the transient response in relation to possible root configurations is included. A root-locus chart is provided for “universal” use. Results from an analog computer are shown to be agreeable with those in this paper.
The Study of Transients in Linear Feedback System by Conformal Mapping and the Root-Locus Method
Authors: Yeh Victor C. M. 
Published: July 2022

Abstract
The correlation between frequency and transient analysis of linear feedback systems, either degenerative or regenerative, through conformal mapping is pointed out. The root locus is a special case of the conformal mapping obtained by transforming the real axis of the inverse Y(s)-plane onto the s-plane. A method for deriving the equations of root loci is presented, and the basic shapes of root loci are shown. The shifting and reshaping of root locus by means of controller adjustments are discussed.
Heat-Transfer and Friction Characteristics for Gas Flow Normal to Tube Banks—Use of a Transient-Test Technique
Authors: Kays W. M. , London A. L. , Lo R. K. 
Published: July 2022

Abstract
Heat-transfer and flow-friction design data are presented for flow normal to circular tube bundles for the Reynolds-number range, 500 to 20,000 (based on tube diameter). Six staggered circular tube patterns and one in-line arrangement were tested. Tentative correlations are presented for the staggered arrangements allowing interpolation of the test results to obtain design data partially covering a transverse pitch-ratio range from 1.25 to 2.50, and a longitudinal pitch-ratio range from 0.75 to 1.50. Data also are provided so that the influence of the number of tube rows on the mean coefficient may be estimated accurately. These results are of interest in applications involving small-diameter tubes and low-density fluids, as, for example, the gas-turbine regenerator. They supplement the high Reynolds-number data of Pierson, Huge, and Grimison, and the low Reynolds-number viscous-flow-range data of Bergelin, Colburn, et al., by providing needed information for the intermediate range. A transient-test technique was employed in obtaining these data. Several tests employing a conventional steady-state technique also were made to demonstrate the validity of the transient method. The advantages and limitations of the transient method are considered in detail.
Erosion by Melting and Evaporation
Authors: Berman Kurt 
Published: July 2022

Abstract
This work represents an investigation of the erosion of solid bodies placed in an air stream. The test specimens were formed into cylindrical and conical shapes. Ice, acetophenone, and para-dichloro-benzene were used as the materials for the solid models. It was possible to correlate the rate of erosion as a function of the Reynolds number.
Calculation of Transient Temperatures in Pipes and Heat Exchangers by Numerical Methods
Authors: Dusinberre G. M. 
Published: July 2022

Abstract
An interest has been shown in the prediction of transient phenomena in pipes and heat exchangers. The numerical methods for the solution of such problems exist in a general form in the literature, but it may be of service to research workers and designers to have these methods developed into explicit iteration formulas and computation guides. This is done for a number of cases.
Effect of Exhaust Pressure on the Economy of Condensing Turbines
Authors: Keller A. , Downs J. E. 
Published: July 2022

Abstract
The purpose of this paper is to provide quick and accurate methods of determining the change in heat rate, nonextraction steam rate, or turbine capability, resulting from changes in the exhaust pressure of condensing turbines. The methods are applicable for turbines from 25,000 kw to the maximum size built by the authors’ company. It is believed that these data will be useful to the power-station designer in selecting between alternative turbine designs with different last-stage-bucket annulus areas available in the larger ratings, and also helpful in the selection of condenser size. It also will be useful to the operating engineer in determining when condenser maintenance is advisable, for correcting test data to base exhaust pressure for comparison with guarantee or expected information, and showing the desirability of operation with less than maximum condenser circulating-water pump capacity in cold weather.
Convective Heat Transfer for Mixed, Free, and Forced Flow Through Tubes
Authors: Eckert E. R. G. , Diaguila A. J. 
Published: July 2022

Abstract
This paper presents current knowledge on heat transfer caused by simultaneously occurring free and forced convection in tubes. It discusses the results of experiments that have been conducted by the NACA on mixed, free, and forced-convection heat transfer in turbulent flow through a vertical tube with a length-to-diameter ratio of 5. In these studies, forced air flow was directed parallel or opposite to the flow direction which free-convection flow alone would have under the same temperature conditions. Results of experiments made by other investigators, when analyzed in the same way as the NACA experiments, make it possible to generalize and extend the heat-transfer relations established. A calculation by R. C. Martinelli and L. M. K. Boelter for laminar mixed, free, and forced flow in parallel direction, and its extension to flow in opposite direction furnish information on heat transfer in the laminar-flow range.
Heat Transfer to Lead-Bismuth and Mercury in Laminar and Transition Pipe Flow
Authors: Johnson H. A. , Hartnett J. P. , Clabaugh W. J. 
Published: July 2022

Abstract
Experimental heat-transfer results in the low Reynolds modulus range of 1000 to 10,000 are reported for two different liquid metals, lead-bismuth eutectic and mercury. The single heat exchanger used in both series of tests was a ¾-in., 18-gage, 4-ft-long mild-steel tube. Similar heat-transfer tests with water in laminar and turbulent flow were performed with this same tube before and after each liquid-metal series, and the agreement of the turbulent-water tests with previous published results supports the liquid-metals test procedure. The data for both liquid metals, including flow in the upward and downward directions, are correlated on a Nusselt-Peclet basis with a single curve representing all experimental results with a maximum deviation of 20 per cent. The experimental Nusselt values decrease from approximately 6 at Reynolds number of 10,000 down to 1 at a Reynolds number of 1200, and consequently are considerably lower than the theoretical constant heat-rate laminar-flow Nusselt value of 4.36 (6). Possible causes for this behavior which have been investigated and found to be inadequate when considered independently include: (a) Insulating gas-layer or oxide-film fouling at the heated surface; (b) nonwetting; (c) uncertainties in property values; (d) axial-conduction effects. Although no supporting data are available, a distortion of the velocity profile from the parabolic distribution appears to be the most plausible explanation.
Heat Transfer in a Gas-Fired Furnace
Authors: Genna S. J. , Nolan E. J. , Furczyk A. A. 
Published: July 2022

Abstract
The general problem of heat transfer in a gas-fired furnace is examined. A method of analysis is introduced for determining the contributions of the various modes of heat transfer. A particular furnace, gas-fired with non-luminous flames, is investigated in the temperature range of 1750 to 2110 F. The results indicate that approximately 80 per cent of the heat is transferred by radiation from the furnace walls to the charge being heated and the remainder by gas convection and gas radiation.
Electronic-Control Method for the Precision Expanding of Tubes
Authors: Dudley F. E. 
Published: July 2022

Abstract
As conditions of temperature and pressure become more severe in modern heat-transfer equipment, the art of expanding tubes must keep abreast of this progress in engineering. This is especially true with tubes being expanded at both ends where metal-to-metal fixed joints are required to maintain absolute leaktight integrity and mechanical stability for safe and efficient operation. Overexpanding imposes excessive cold-work stresses in tubes and sheets, resulting in early failures. Underexpanding carries its burden of leakage and added nonproductive hours for correction in the field. This paper relates to progress in the precision expanding of tubes during the past few years.
Measurement of Stresses Imposed on Wheels in Diesel-Locomotive Service
Authors: Olson L. L. 
Published: July 2022

Abstract
The dieselization of railroads has been accompanied by many reports of locomotive-wheel failures. Laboratory tests by wheel manufacturers have been helpful but inadequate, since actual operating conditions were not duplicated. This paper describes a test program, now in its preliminary stages, which will undertake to secure necessary data. The objectives, test procedures, and instrumentation of the proposed program are outlined.
A Short Method for the Evaluation of the Effect of Some Thermal-Cycle Variations on Steam-Turbine Heat Rates
Authors: Fulton S. D. 
Published: July 2022

Abstract
The purpose of this paper is to present a short method of evaluating the effect of several thermal-cycle variations on steam-turbine heat rates, utilizing the data given in a heat balance. The method is based on the fact that the product of the input to a cycle and its thermal efficiency equals the output. To use this fact a method for determining the thermal efficiency from any extraction point to the turbine exhaust is presented. Equations derived for the various changes in the cycle make determination of heat-rate changes quite simple. A high order of accuracy is obtained by computing only changes in input and output.
The Controlled-Circulation Boiler
Authors: Armacost W. H. 
Published: July 2022

Abstract
From the standpoint of circulation there are two general types of boilers in operation in this country. These are natural circulation based on the conventional “thermal circulation head,” and controlled circulation based on the use of a pump to distribute and circulate the water through the heat-absorption areas. The author’s company supplies both types, having pioneered in the design and development of natural-circulation as well as controlled-circulation boilers. With the trend toward larger high-pressure units, industry is directing more and more attention to the controlled-circulation type. Therefore it appears desirable to summarize the information regarding these boilers. This paper deals largely with (a) the development of these boilers, (b) presently preferred designs, (c) operating features, results, and characteristics, and (d) brief reference to installations in this country.
Mechanical Features of the Tandem Helicopter Drive System
Authors: Plume W. F. 
Published: July 2022

Abstract
In the shaft-driven helicopter, drive-system reliability plays a large part in the safety of the helicopter. Drive-system reliability is established by extensive development testing and is maintained by quality control and production load runs. This paper describes in detail the transmissions and clutches of two types of tandem-rotor helicopters and the methods used for testing.
Evaluation of Transient Temperatures and Stresses
Authors: Fritz R. J. 
Published: July 2022

Abstract
Solutions to the one-dimensional, heat-conduction equation for arbitrary surface temperature transients are treated by superposition of other solutions and by a concept of thermal reflections. The maximum thermal stresses are given for a flat plate due to a given surface temperature change at a linear rate. Thermal stresses in thin cylindrical shells are discussed, and an example is evaluated.
Design factors are discussed briefly, mainly by citing critical problems and giving references. A comprehensive bibliography is presented.
Evaluation of Bandsaw Performance
Authors: Colwell L. V. , McKee R. E. 
Published: July 2022

Abstract
Methods of evaluating bandsaw performance are presented and typical performance characteristics are discussed. Tests indicate that bandsawing has orderly and predictable machinability characteristics very similar to other machining operations. Cutting speed and feed rate or feeding force are the more important variables requiring careful selection and control. Tests on sawing titanium show that positive power feed is almost a necessity to prevent premature breakdown of the band.
The Tabulation of Imperfect-Gas Properties for Air, Nitrogen, and Oxygen
Authors: Hall Newman A. , Ibele Warren E. 
Published: July 2022

Abstract
Recent theoretical developments of intermolecular forces have established a basis upon which a valid extension of gas-property data may be prepared. This paper establishes the fact that deviation from perfect-gas behavior may be expressed fundamentally by the compressibility factor. Tables of virial coefficients and temperature derivatives for air, nitrogen, and oxygen are given, as well as tables of compressibility factors for these three gases.
Cyclic Heating Test of Main Steam Piping Materials and Welds at the Sewaren Generating Station
Authors: Weisberg H. , Soldan H. M. 
Published: July 2022

Abstract
This paper describes a continuation of previously reported cyclic heating tests of austenitic and ferritic piping and welds, representing the main steam piping installed at Sewaren Generating Station. In the current test, a section made up of these materials was subjected to thermal cycling from room temperature to 1100 F, and from atmospheric pressure to the operating pressure of 1500 psi. The heating and cooling rates were somewhat more severe than are experienced during regular starting and shutting-down conditions in the actual piping systems. The results show that 100 cycles did not produce any cracking. It is proposed to continue the test to destruction by further cycling and the addition of external bending forces.
Some 12 Per Cent Chromium Alloys for 1000 F to 1200 F Operation
Authors: Newhouse D. L. , Seguin B. R. , Lape E. M. 
Published: July 2022

Abstract
This paper presents a discussion of important engineering properties of some martensitic 12 per cent Cr alloys for use at temperatures up to 1200 F. Detailed high-temperature creep-relaxation and stress-rupture data are given for 12 per cent Cr (Type 403) and for six alloy modifications including 12 per cent Cr-Co-W-V, 12 per cent Cr-W-V, 12 per cent Cr-Mo-V, 12 per cent Cr-Mo-W-V, 12 per cent Cr-Cb, and 12 per cent Cr-Ni-W. Other properties such as thermal expansion, modulus of elasticity, resistance to stress corrosion, and so forth, are discussed. Some of the modified 12 per cent Cr alloys offer a combination of properties which makes them attractive for a number of high-temperature applications.
The Frequency-Response Approach to the Design of a Mechanical Servo
Authors: Helm H. A. 
Published: July 2022

Abstract
The frequency-response method of analysis has proved extremely valuable in the design of electronic feedback systems. This paper illustrates the application of this method to the design of completely mechanical systems. Basic relations between the mechanical elements are pointed out and the necessary feedback concepts are developed for mechanical systems. These concepts are illustrated by the actual step-by-step design of an automatic contour-following lathe using entirely mechanical, hydraulic, and pneumatic control elements.
Application of Frequency-Analysis Techniques to Hydraulic Control Systems
Authors: Hall A. C. 
Published: July 2022

Abstract
Hydraulic control systems, while inherently nonlinear, under many conditions can be studied by means of a linear approximation. Performance may be predicted by this approximation with reasonable accuracy provided the change in fluid flow during a transient is small compared to the steady-state value of the flow. A valve-motor control system is studied by linear analysis and the frequency-response characteristic obtained. The transfer function of this system is of the third order if the servomotor load is a mass. Expressions for the damping ratio, natural frequency, and sensitivity are obtained.
Synthesis of Optimum Feedback Systems Satisfying a Power Limitation
Authors: Westcott J. H. 
Published: July 2022

Abstract
The paper describes two methods of synthesizing feedback systems in which stability considerations are qualified by an overriding limit on power demand. The three basic requirements for either method are (a) a spectral density function of input signals, (b) a transfer function of fixed elements (i.e., basic elements essential for the performance of the task), and (c) the maximum rating of the power source. Examples are given. In one method the form of the stabilizing means has to be specified. The criterion, that the mean-square error be a minimum subject to the power limitation, is applied. This gives as a result the optimum design parameters of the specified stabilizing means. The other method, based upon the same criterion, uses a variational principle. A solution by this method gives a stabilizing means for the system which, within the specified power limit, cannot be improved. One example of this method illustrates the desirability of allowing a finite time delay between the input and the output of a feedback system.
Recent Advances in Nonlinear Servo Theory
Authors: Loeb J. M. 
Published: July 2022

Abstract
This paper concerns the so-called “filtered nonlinear servos,” i.e., servos where the signal undergoes a filtering effect from a linear part of the device. “Hereditary phenomena,” such as Coulomb friction, gear backlash, and so on, are dealt with. A general stability criterion is derived, and it is shown how the Nyquist criterion appears as a particular case. The criterion indicates whether or not a servo is liable to hunt, but it is still necessary to state whether or not the possible hunting will have a limited amplitude. An approach to this problem is sketched and it is shown how the first results may be considered as quantitatively valid for quasi-linear systems. Some conclusions previously derived by assuming the transfer functions to be analytic appear as a limiting case of the present results.
The Use of Zeros and Poles for Frequency Response or Transient Response
Authors: Evans W. R. 
Published: July 2022

Abstract
The characteristic equation of a control system is often of the form 1/KG(s) + 1 = 0, in which G(s) is (s − q1) (s − q2)… /(s − p1) (s − p2)… Each factor of G(s), such as (s − p1), is a complex variable which can be plotted as a vector in the s-plane from the pole p1 to the point s. The complex product G(s) is itself a vector whose magnitude is the product of magnitudes and whose angle is the sum of the angles of its factors. Frequency response is computed directly for s points along the jω-axis. In order to find the roots of 1/KG(s) = −1, the locus of s is sketched, where for each point on this locus the total angle of G(s) is equal to 180 deg; a point on this locus is then a root if K = 1/|G(s)|. For given initial conditions the Laplace transform permits the transient response of the system to be written directly.
Equilibrium Behavior of a Tethered Autogyro: Application in Extended Flight and Power Generation
Authors: McConnell Jonathan , Das Tuhin 
Published: July 2022

AbstractIn this article, we study the characteristics of steady autorotation of a tethered autogyro. The phenomenon of autorotation refers to the natural spinning of a rotor in a wind field. We explore the viability of tethered autogyros as unmanned aerial vehicles (UAVs) for long-duration and energy efficient hovering applications, such as in monitoring or surveillance. The tether provides mooring and can be used to power the rotor and to transmit wind power to the ground when suitable. This is a novel application of autorotation. It requires a generalized formulation and modeling of autorotation, beyond what is reported in the literature. We adopt a model-based approach where the blade element momentum (BEM) method and catenary mechanics are used to model the aerodynamics and the tether, respectively. The resulting model is highly nonlinear and numerical methods are proposed to solve for the equilibria. The model is validated against existing simulation and experimental results in the literature. It is extended to incorporate new features that are pertinent to our application, such as low rotor speeds, regenerative torque for power generation, combining catenary mechanics with aerodynamics, and varying atmospheric conditions with altitude. We characterize the autorotational equilibria over a range of operating conditions involving multiple independent variables. The analysis reveals an optimal operating range of the tip speed ratio of the autogyro under equilibrium. It also indicates the possibility of power generation in large autogyros stationed at high altitudes.