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RESEARCH PAPERS

J. Basic Eng. 1960;82(4):759-763. doi:10.1115/1.3662740.

When a column of fluid moving with uniform velocity is instantaneously stopped at the downstream end a pressure wave is propagated upstream. In an inviscid fluid the wave is a step discontinuity, and the pressure so calculated serves as an easily obtained upper bound for all practical “water-hammer” problems, the exact solution of which may be either difficult or impossible to obtain. This paper describes an analysis of viscous dispersion in relation to the upper bound. The conclusion is reached that in problems of practical interest the bound is not significantly changed by the dispersive effects of viscosity.

Commentary by Dr. Valentin Fuster
J. Basic Eng. 1960;82(4):765-775. doi:10.1115/1.3662744.
Abstract
Topics: Stability , Surges
Commentary by Dr. Valentin Fuster
J. Basic Eng. 1960;82(4):784-789. doi:10.1115/1.3662753.
Abstract
Topics: Cavitation
Commentary by Dr. Valentin Fuster
J. Basic Eng. 1960;82(4):795-802. doi:10.1115/1.3662761.

The conjoint mechanical-chemical destruction of metals by accelerated cavitation in a magnetostriction apparatus indicates relative effects of the metal properties (hardness, metallurgical structure, corrosion-fatigue limit) and of the liquid characteristics (temperature, pressure, wettability) which have been confirmed by field experience in hydraulic turbines and in water-cooled diesel cylinder liners.

Commentary by Dr. Valentin Fuster
J. Basic Eng. 1960;82(4):808-818. doi:10.1115/1.3662770.

An experimental procedure has been developed which makes possible accurate and reproducible determinations of cavitation damage. This procedure has been applied to a study of the effect of cathodic currents on cavitation damage. A series of experiments, in which the test liquid was a solution of salt in water, showed a reduction in cavitation weight loss for all of the materials examined when the test specimen was made the cathode of an electrolytic cell and when the conditions were such that gas was evolved at the specimen surface. This protective effect against cavitation damage increased with increasing magnitude of the cathodic current. These observations support the view that the protective effect was due to the layer of hydrogen gas evolved on the surface of the specimen. A similar protective effect was observed when the specimen was made the anode in a test liquid which was buffered distilled water; in this situation the gas evolved at the specimen surface is oxygen. Additional evidence for this protective mechanism of a gas layer on the specimen surface was found in a series of experiments in which the voltage applied to the cell was reduced to a level at which no gas was evolved on the surface. There was then no protective effect with the specimen cathodic or anodic.

Commentary by Dr. Valentin Fuster
J. Basic Eng. 1960;82(4):821-828. doi:10.1115/1.3662775.

The static head at pump suction at the time of cavitation inception was correlated for water and for 1500 F NaK on the basis of the differences of the vapor pressures of the two liquids. The difference between the vapor pressures, for the same conditions of pump speed and liquid flow, was added to the water-test cavitation inception value; this proved to be a good approximation to the experimental value found for cavitation inception with NaK.

Commentary by Dr. Valentin Fuster
J. Basic Eng. 1960;82(4):829-838. doi:10.1115/1.3662778.

The creep-rupture properties and the creep behavior of a series of 80 Ni-20 Cr alloys were investigated over the 1200 to 1800-F range. In the group were two vacuum-melted and three air-melted alloys. Among these five heats there were small but important differences in minor constituents such as silicon, manganese, sulfur, and possible tramp elements, primarily as a result of the melting practice in each case. Of particular interest in this study was the variation in ductility which the various alloys exhibited in creep-rupture tests which lasted from a few minutes to more than 1000 hr. A close examination of ductility behavior was undertaken by breaking down the creep curve into primary, secondary, and third-stage creep as a function of stress and temperature. It is shown that the stress-rupture properties are not affected over a wide temperature and stress range by a change in minor constituents, whereas the ductility behavior can vary considerably.

Commentary by Dr. Valentin Fuster
J. Basic Eng. 1960;82(4):839-846. doi:10.1115/1.3662779.

A method using finite-difference recurrence relations is presented for direct extrapolation of families of curves. The method is illustrated by applications to creep-rupture data for several materials and it is shown that good results can be obtained without the necessity for any of the usual parameter concepts.

Topics: Creep , Rupture
Commentary by Dr. Valentin Fuster
J. Basic Eng. 1960;82(4):848-853. doi:10.1115/1.3662782.
Abstract
Commentary by Dr. Valentin Fuster
J. Basic Eng. 1960;82(4):855-866. doi:10.1115/1.3662785.

The effect of cold deformations as encountered in tube and superheater fabrication and of temperature and time of annealing on the grain-size characteristics of 18Cr8Ni-Ti is demonstrated by laboratory experiments with material from six heats of steel. It is shown that cold-drawn tubing retains a relatively uniform small grain size at annealing temperatures up to about 1900 F to 1950 F and that above this temperature individual grains begin to grow at an accelerated rate, leading to a mixed grain-size structure. Annealing times between 5 and 15 minutes caused only insignificant differences in the over all grain size, but extension of exposure to 30 minutes produced a noticeably larger grain structure. Small cold deformations as may be introduced into the material by tube straightening can, when followed by a final anneal, cause excessive localized grain enlargements. Observations pointed to the possibility that materials with high Ti/C ratios may retain a predominantly small grain size at annealing temperatures as high as 2050 F.

Commentary by Dr. Valentin Fuster
J. Basic Eng. 1960;82(4):867-880. doi:10.1115/1.3662786.

Testing techniques employed in determining the elastic moduli, that is, Young’s modulus, shear modulus, and Poisson’s ratio, at room and elevated temperatures are described. These techniques depend on static or dynamic measurements. A comparison and an analysis of test results determined by these two methods are presented. The effect of composition, grain size, and various transformations on the elastic moduli or their temperature dependence is discussed. A review of techniques and experimental data on the effect of high strain rates on plastic and rupture behavior of metals, and alloys at elevated temperatures is presented. It is shown that recovery effects explain qualitatively the results obtained. A brief description of the various stages of recovery is also presented. The variation of hardness with temperature is discussed for pure metals and alloys, including a description of a typical hot-hardness tester. The relationship between hardness and tensile strength, creep, and creep-rupture behavior is briefly summarised. The use of the hot-hardness tester as a research tool for following solid-state reactions at elevated temperatures is discussed. These reactions may depend on temperature, time, or plastic strain or a combination of these.

Commentary by Dr. Valentin Fuster
J. Basic Eng. 1960;82(4):882-886. doi:10.1115/1.3662789.

The microstructure of several 80 Ni-20 Cr alloys was studied after creep at 1500 and 1800 F with respect to the influence of atmosphere. In particular the propagation of intercrystalline cracks was investigated. By comparison with tests conducted in argon it can be shown that the atmosphere has a strengthening effect in all cases. The mechanism of this effect changes with the variation of minor constituents in the metals (such as silicon and Mn/S ratio). Crack propagation is strongly affected by the melting process, which influences the purity of the grain boundaries.

Commentary by Dr. Valentin Fuster
J. Basic Eng. 1960;82(4):887-892. doi:10.1115/1.3662790.

This paper summarizes data obtained at Oklahoma State University under contract with ASME through RCMPE to measure the deflection characteristics of commercially produced Bourdon tubes. The method of measurement was designed to produce accurate results without including effects of end constraints. Reasonably good agreement with theory was shown. Deviation of the cross-sectional shape of the tube from ideal flat oval shape could not be shown to influence the behavior. An outline of a method of preliminary design of a Bourdon tube is given. Suggestions are made for additional research using stress free electroformed tubes of ideal shapes.

Topics: Deflection , Shapes , Stress , Design
Commentary by Dr. Valentin Fuster
J. Basic Eng. 1960;82(4):894-898. doi:10.1115/1.3662792.

Experiments described in this paper show that a rotatable intermediate sleeve in a journal bearing will change the average oil film velocity and hence can be made to control oil whip frequency. This device should allow oil whip frequency control of shafts running at two or more times their critical speed.

Commentary by Dr. Valentin Fuster
Commentary by Dr. Valentin Fuster
J. Basic Eng. 1960;82(4):901-907. doi:10.1115/1.3662794.

Shutdown of the Babcock & Wilcox nuclear reactor water coolant pumps will cause check valves to close which will induce the generation of water hammer in the system. The magnitude, frequency, and duration of possible pressure oscillations in the pipeline and the discharge of the pressure oscillations into the attached plenum chamber were evaluated. Although the plenum chamber contains a great number of suspended rods, it was possible to establish the upper bound for the pressure loading across the internal structure of the plenum chamber at various stations for determination of design criteria.

Commentary by Dr. Valentin Fuster
J. Basic Eng. 1960;82(4):912-919. doi:10.1115/1.3662800.

An analytical solution which includes frictional effects is developed for the pressure occurring in a pipeline when Poiseuille flow is stopped by the sudden closure of a valve. Limitations and deficiencies of past solutions of the same problem have been overcome in the present analysis. It is shown that for most pipelines of practical interest the pressure is given by the sum of four traveling waves multiplied by a time-decaying exponential; evaluation is easily accomplished with a few simple slide-rule calculations. The computed pressures are shown to compare closely with experimental measurements.

Commentary by Dr. Valentin Fuster
J. Basic Eng. 1960;82(4):921-927. doi:10.1115/1.3662803.

The conditions for the equilibrium of two vortexes in a two-dimensional flow through a duct or diffuser are derived. Potential-flow considerations and a few basic results from viscous-flow theory are used for the discussion of the role of cusps as separation control and trapping devices for standing vortexes. The investigations are applied to cusp diffusers especially with regard to the wind tunnel of the James Forrestal Research Center of Princeton University.

Commentary by Dr. Valentin Fuster
J. Basic Eng. 1960;82(4):929-940. doi:10.1115/1.3662806.

A mixed flow impeller design was tested with six, five, and four vanes in a closed water loop to study the effects of cavitation on hydraulic performance and the results were compared with the work of other investigators. Two idealized flow models for incipient cavitation were derived to illustrate limits of cavitation design. It was found that both vane blockage and solidity effects are important when designing for optimum cavitation performance. Data showing incidence and speed effects plus the tip static pressure profiles in cavitating and noncavitating flow are also presented.

Commentary by Dr. Valentin Fuster
J. Basic Eng. 1960;82(4):941-945. doi:10.1115/1.3662809.

The simultaneous occurrence of vaporous and gaseous cavitation on hydrofoils is considered. The experimental results show that gaseous cavitation occurs at much higher ambient pressures than that for the vaporous cavitation resulting in desinent-cavitation numbers twice the minimum-pressure coefficient of the hydrofoil. The analysis indicates that the difference between the desinent-cavitation number for the gaseous cavitation and that for the vaporous cavitation is proportional to the dissolved air content and inversely proportional to the square of the velocity.

Commentary by Dr. Valentin Fuster
J. Basic Eng. 1960;82(4):947-960. doi:10.1115/1.3662812.

A compressible flow jet pump theory is evolved which can be more easily interpreted for design purposes than existing theories. It consists of a one-dimensional analysis based on the momentum equation and on complete mixing, used in conjunction with an over-all pressure recovery factor which is found experimentally. Tests on a small jet pump are described and from the results it is shown that the overall pressure recovery factor can be related to a single parameter in the analysis for all operating conditions of each general pump configuration. In this way a general method for the correlation of results and for the design of jet pumps is established.

Commentary by Dr. Valentin Fuster
J. Basic Eng. 1960;82(4):961-968. doi:10.1115/1.3662813.

The author shows that even in steady uniform turbulent channel flow there exist on the average mean accelerations and forces acting on fluid particles. These are computed from the flow equations and Laufer’s data. There exist both normal and axial mean accelerations, the latter highly negative (15g and more) in the dissipative “transition” layer near the wall, elsewhere constant. There most river bed-load and dune sand movement occurs. Mixing and sediment transportation are explained dynamically. Mean shear is shown to exist mainly in the dissipative layer. Mean turbulent trajectories are defined.

Commentary by Dr. Valentin Fuster
J. Basic Eng. 1960;82(4):973-979. doi:10.1115/1.3662818.

Presentation is made for the design concepts of a novel diffuser that handles supersonic flow at the exit of radial and mixed flow compressors. The guide vanes incorporating a V shape at the inlet are shown to offer potentialities of a shock free deceleration of the supersonic flow. Optimum diffusion of a high-speed flow is considered. The results are applied to the design of two sets of guide vanes for the diffusing system. The experimental evaluation of these guide vanes confirms the original conceptual thinking, with a highest diffuser performance of 0.792 at an inlet Mach number of 1.3. Effect of the blade loading and of the subsonic inlet Mach number on the guide vanes are presented. Actual performance of the diffuser in a compressor of a gas turbine is discussed.

Commentary by Dr. Valentin Fuster

DISCUSSIONS

Commentary by Dr. Valentin Fuster
Commentary by Dr. Valentin Fuster
Commentary by Dr. Valentin Fuster
Commentary by Dr. Valentin Fuster
Commentary by Dr. Valentin Fuster
Commentary by Dr. Valentin Fuster

TECHNICAL BRIEFS

J. Basic Eng. 1960;82(4):980-982. doi:10.1115/1.3662821.
Abstract
Commentary by Dr. Valentin Fuster

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