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J. Basic Eng. 1972;94(4):705. doi:10.1115/1.3425530.
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Abstract
Commentary by Dr. Valentin Fuster

RESEARCH PAPERS

J. Basic Eng. 1972;94(4):706-714. doi:10.1115/1.3425531.

Reciprocating pumps have been employed in conjunction with air vessels and fluid accumulators for a long time in order to reduce maximum cylinder pressures and energy wastage in friction. More recently, diaphragm pumps, run at high speed, have been built utilizing a hydraulic accumulator or capacitance in conjunction with a hydraulic inductance, in order to greatly increase the flow output. Volumetric efficiencies of over 250 percent have been obtained. The present paper describes briefly this induced flow principle and then compares theoretical solutions with experimental measurements taken in the first commercially available pump of this type.

Commentary by Dr. Valentin Fuster
J. Basic Eng. 1972;94(4):715-719. doi:10.1115/1.3425532.

A wetted-wall column was used to measure liquid flow rates in capillary grooves on vertical surfaces. The test facility contained interchangeable grooved surfaces (2-in. OD) which contacted a liquid reservoir in such a way that the test surfaces were partially wetted by capillary action. The wetted portion was exposed to a forced-convection air stream, so that surface evaporation took place because of the different partial pressures of the vapor at the liquid-vapor interface and at the center of the air stream. All data were obtained in steady-state and nearly isothermal conditions. Experimental results with carbon tetrachloride on brass surfaces were in agreement with approximate predictions, which were computed for evaporative heat transfer and then related to mass transfer by using Reynolds analogy for pipe flow.

Commentary by Dr. Valentin Fuster
J. Basic Eng. 1972;94(4):720-728. doi:10.1115/1.3425533.

The growth of planar jets is studied using the hydrogen bubble technique of flow visualization. A five-fold range of nozzle exit Reynolds number (1860 to 10,800) is considered. Generation of streaklines and timelines permits characterization of the process of vortex formation and coalescence. Both symmetrical and asymmetrical modes of vortex growth and coalescence, along with the resultant deformation of the jet core flow, are examined. Nascent and mature stage coalescence are defined and portrayed. Vortex axial transport velocity and frequency of formation of the vortices are evaluated for selected Reynolds numbers.

Commentary by Dr. Valentin Fuster
J. Basic Eng. 1972;94(4):731-738. doi:10.1115/1.3425537.

Solutions for the point mean flow field properties in the turbulent core for suspension flow in a vertical circular tube have been developed for the fully developed flow condition. For uniform particle density flows, the suspension velocity distribution is logarithmic and is given in terms of parameters which must be determined by experiment, but the paper shows that all flows which satisfy the conditions of the model should follow the same universal law. Analytic expressions for the gas velocity and the slip velocity are also presented. The purpose of the analysis was to produce solutions of practical utility and to provide a basis for the extrapolation and interpretation of experimental results which are presented in another paper.

Commentary by Dr. Valentin Fuster
J. Basic Eng. 1972;94(4):739-747. doi:10.1115/1.3425538.

An experimental investigation has been made of a swirling jet having a moderate ratio of swirling to axial momentum. Measurements showed that the flow achieved a self-similarity for the mean velocities rather quickly while the normal turbulent intensities reached a self-similar state after a longer period of jet development. Conservation arguments were used to predict streamwise decay rates for the mean quantities. The analysis showed that the maximum axial and swirling velocity components should vary asymptotically as (x − x0 )−1 and (x − x0 )−2 , respectively. The experimental results confirmed this satisfactorily. The minimum static pressure was predicted to vary at a rate proportional to (x − x0 )−4 . Measurements indicated, however, that the relation was closer to (x − x0 )−2 . Better agreement with the data was achieved when the analytical expression was adjusted for the effect of the turbulence terms. The entrainment rate and angle of spread for the swirling jet were found to be nearly twice that of the non-swirling free jet.

Commentary by Dr. Valentin Fuster
J. Basic Eng. 1972;94(4):749-754. doi:10.1115/1.3425541.

Drag reduction caused by ejecting additive solutions from a slot into a pure-water boundary layer on a flat plate has been systematically studied. Results include drag measurements for a plane boundary, smooth and rough, with various openings of the slot and with various concentrations and discharges of the ejected additive solution. Conclusions have been drawn on the additive requirement in external flows and on the ejection technique for an optimum drag reduction.

Commentary by Dr. Valentin Fuster
J. Basic Eng. 1972;94(4):757-764. doi:10.1115/1.3425545.

The available methods for determining the thermal properties of compressible fluids by flow calorimetry are reviewed and an analysis is given for the method of determining heat capacity ratios by passing the fluid at low and high pressures through a heat exchanger. The design of the heat exchanger calorimeter and its associated equipment are described in detail. The performance of the equipment in determining the heat capacities of nitrogen was evaluated at temperatures of 60.2, 75.7, and 150.4 deg C and at pressures up to 2200 psi. The results were compared where possible with those of other workers. Agreement was within about ±0.5 percent which is the anticipated accuracy of the method.

Commentary by Dr. Valentin Fuster
J. Basic Eng. 1972;94(4):765-769. doi:10.1115/1.3425548.

The complete, time-dependent Navier-Stokes equations are expressed in conservation form and solved by employing an explicit finite difference numerical technique which incorporates artificial viscosity terms of the form first suggested by Rusanov for numerical stability in the vicinity of shock waves. Surface boundary conditions are developed in a consistent and unique manner through the use of a physically oriented extrapolation procedure. From numerical experimentation an extended range for the explicit stability parameter is established. Also employed is an additional convergence parameter which relates incremental spatial steps. Convergence of the transient solution to a steady state flow was obtained after 400 to 500 time steps. Sample solutions are presented for supersonic flow of air over the leading edge of a slightly blunted flat plate, past a backward facing step, and in the near wake of a blunt trailing edge. Free-stream Mach numbers from 2 to 10 are included in the sample computations.

Commentary by Dr. Valentin Fuster
J. Basic Eng. 1972;94(4):771-776. doi:10.1115/1.3425551.

Experiments were performed to evaluate the influence of yaw angle on circular cylinder pressure drag and near wake characteristics in the range of Reynolds numbers 2000 to 10,000. It was found that the transition in the wake from laminar to turbulent motion was significantly promoted as the angle of yaw increased. As a result, wake properties such as base pressure and position of transition to turbulence do not obey the Independence Principle which requires that properties be dependent only on the normal component of the free-stream conditions.

Commentary by Dr. Valentin Fuster
J. Basic Eng. 1972;94(4):777-787. doi:10.1115/1.3425553.

A visualization study of the flow through a three ft dia model of a four bladed inducer, which is operated in air at a flow coefficient of 0.065, is reported in this paper. The flow near the blade surfaces, inside the rotating passages, downstream and upstream of the inducer is visualized by means of smoke, tufts, ammonia filament, and lampblack techniques. Flow is found to be highly three dimensional, with appreciable radial velocity throughout the entire passage. The secondary flows observed near the hub and annulus walls agree with qualitative predictions obtained from the inviscid secondary flow theory. Based on these investigations, methods of modeling the flow are discussed.

Commentary by Dr. Valentin Fuster
J. Basic Eng. 1972;94(4):788-794. doi:10.1115/1.3425554.

This paper describes an experimental investigation of two-phase, air-water nozzle flows including critical or choked flow. Five different nozzle geometries were used. The nozzles exhausted to atmospheric pressure from stagnation pressures of 16 to 55 psia. The quality (mass fraction of air flowing) ranged from 2 to 35 percent. A feature of the study was the injection system which was designed to minimize the entrainment of liquid into the gas phase. The data were found to be described within about 10 percent by modifying separated flow theory by a simple “blockage factor” correlation.

Commentary by Dr. Valentin Fuster
J. Basic Eng. 1972;94(4):795-800. doi:10.1115/1.3425557.

The results of a momentum integral solution of the three-dimensional turbulent boundary layer on the confining wall of an impinging jet are presented. This geometry provides a boundary layer where large gradients in the streamwise and especially the transverse direction occur and hence is a severe test of momentum integral methods. The solution utilizes the Head entrainment function and the Ludwieg and Tillmann wall shear law, with no restriction on cross flows. An extensive comparison with experimental results show good to moderate agreement in the integrated flow parameters, with a strong dependence on the free-stream or edge condition to the boundary layer flow.

Commentary by Dr. Valentin Fuster
J. Basic Eng. 1972;94(4):804-810. doi:10.1115/1.3425562.

The gas removal process during electrolysis is studied with the aim of identifying hydrodynamic transitions, analogous to those which occur in boiling. The local peak in the electrolysis gas flux is observed during electrolysis from a horizontal cylindrical cathode. This transition point is shown to correspond with Moissis and Berenson’s “first transition” in nucleate pool boiling. A prediction of the transition, applicable to either boiling or electrolysis, is developed for the cylindrical heater (or cathode) arrangement. It is compared with 12 experimental data for boiling and electrolysis, and its limitations are discussed. Finally, some attributes of the regime of film electrolysis are identified and discussed.

Commentary by Dr. Valentin Fuster
J. Basic Eng. 1972;94(4):811-816. doi:10.1115/1.3425565.

The problem of steady-state, small amplitude, periodic wave propagation in a viscous, compressible liquid contained in an infinitely long, elastic tube is solved for the complex propagation constants of the two lowest modes of motion. One mode has a speed of propagation and decay constant characteristic of acoustic waves propagating in a liquid; the other mode corresponds to acoustic waves propagating in an elastic tube. The behavior of these two modes is investigated as a function of frequency, viscosity, and tube rigidity. A third mode of motion corresponding to edge loads on the tube is also investigated. This mode, unlike the other two modes, is characterized by a cut-off frequency above which the propagation distance is infinite and below which it is finite.

Commentary by Dr. Valentin Fuster
J. Basic Eng. 1972;94(4):818-823. doi:10.1115/1.3425568.

Normally the energy conversion efficiency of a confined-discharge plasma generator is inversely related to the mean enthalpy of the effluent plasma jet. The present paper describes a technique for increasing both the energy conversion efficiency, defined as the net fraction of the electrical power input transferred to the working fluid, and the mean enthalpy, defined as the net energy transferred to the working fluid per unit mass. A portion of the working fluid is introduced to the discharge through a narrow circumferential slit in the confining duct wall. Heat transfer and fluid dynamic effects associated with this high velocity inflow of cold gas cause the local discharge column to become highly constricted. Concomitant with this local fluid constriction (LFC) is a sharp increase in the local power density, resulting in enhanced energy transfer to the cold gas. Experimental results suggest that for optimum operation the gas injection slit should be located slightly upstream of the axial position where the discharge becomes thermally fully developed.

Commentary by Dr. Valentin Fuster
J. Basic Eng. 1972;94(4):825-832. doi:10.1115/1.3425571.

The collapse of spark-induced cavitation bubbles in a flowing system was studied by means of high speed photography. The migration of cavitation bubbles toward a nearby solid boundary during collapse and rebound was observed. Near its minimum volume the bubble typically formed a high speed microjet, which struck the nearby surface causing individual damage craters on soft aluminum.

Commentary by Dr. Valentin Fuster
J. Basic Eng. 1972;94(4):834-840. doi:10.1115/1.3425574.

The purpose of this study was to review all material relevant to the design, construction, and operation of a large floating columnar platform made of ferroconcrete. Existing platforms, motion analysis, anchoring, powering, assembly and ferroconcrete are discussed. The study indicates that ferroconcrete platforms can be built and that electric power generation sites may be the first application of the idea.

Commentary by Dr. Valentin Fuster
J. Basic Eng. 1972;94(4):841-846. doi:10.1115/1.3425575.

An investigation of the feasibility of fabricating and erecting very large and heavy closure structures for high pressures and in sizes presently considered beyond practical limits.

Commentary by Dr. Valentin Fuster
J. Basic Eng. 1972;94(4):847-852. doi:10.1115/1.3425576.

Bubble inclusions present in cast acrylic plastic generally degrade the mechanical properties of the material. To evaluate the effect of bubbles on the mechanical strength of acrylic plastic, 120 tensile and compressive test specimens were machined from massive acrylic castings with bubble inclusions. The specimens were tested under uniaxial loading condition and effect of bubbles on tensile and compressive strength noted. The stress raiser effect of bubbles caused the tensile specimens to fail at stresses 7 to 30 percent lower than observed in specimens without bubbles. The compressive yield strength was not affected by bubbles. However, here the bubbles served as stress raisers also and caused cracks to initiate at the bubble surfaces when the yield strength of acrylic plastic was reached.

Commentary by Dr. Valentin Fuster
J. Basic Eng. 1972;94(4):853-861. doi:10.1115/1.3425577.

Temperature and the seating arrangement in the flange have a significant effect on the critical pressure of conical acrylic windows. Over 400 acrylic windows with 90 deg conical angle were used in this study to establish experimentally the relationship between thickness to minor diameter ratio (t/D), temperature, seating arrangement in the flange, and critical pressure under short term hydrostatic loading. The data indicates that utilizing 70 deg F as standard of comparison, there is, approximately 20 percent increase in critical short term pressure when 32 deg F, and 20 percent decrease when 90 deg F ambient temperatures are utilized, respectively. It was also found that the short term critical pressure of some conical acrylic windows is influenced by the seating arrangement in the flange. As a rule, an increase in the ratio of minor window diameter to minor flange opening diameter (D/Df ) raised the short term critical pressure of windows with t/D ≥ 0.375 significantly. For windows with t/D < 0.375, it did not raise the critical pressure.

Commentary by Dr. Valentin Fuster
J. Basic Eng. 1972;94(4):862-866. doi:10.1115/1.3425578.

The special case of horizontal wave forces on large vertical cylinders in deep water is considered. The typical application for such a case is the calculation of horizontal forces on column stabilized floating ocean platforms. Existing literature discussing horizontal wave forces on cylinders does not generally agree on how to predict these forces. Since for large diameter cylinders in deep water the maximum force is completely inertial, the problem of deriving a solution is considerably simplified. In this study, an expression for the maximum horizontal wave force on large diameter circular cylinders mounted vertically in deep water has been analytically derived. Experimental model studies were also conducted and the resulting measured forces were within 20 percent of predicted forces. An example of how to predict horizontal wave forces using the methods of this report is given.

Commentary by Dr. Valentin Fuster
J. Basic Eng. 1972;94(4):867-873. doi:10.1115/1.3425579.

Lifting or lowering of very heavy loads in the ocean (1000 tons or more) from any depth under controlled conditions has proven to be very difficult. Lifting very heavy loads from great depths using the present winching or lifting methods is for practical purposes nonexistent. Pontoons and winches have been used for limited loads and limited depths. The problem of breakout forces, buoyancy controls, dynamic wave induced cable stresses, etc., have made very heavy lifts from the ocean depths almost impossible to perform. The Hydrodynamic Winch is a proposed solution to the very heavy undersea lift and control problem.

Commentary by Dr. Valentin Fuster
J. Basic Eng. 1972;94(4):874-878. doi:10.1115/1.3425580.

A linear, inviscid stability analysis is applied to the case of a relatively thin layer of stationary oil over a semi-infinite layer of water flowing at a constant velocity. Predictions of the velocity at which the interface becomes unstable and the effect of the oil depth on this velocity agree qualitatively with observations. Results can be applied to the problem of containing oil with mechanical booms. The model predicts initiation of oil loss by droplet separation from beneath the slick at low current velocities, for example, 0.39 to 0.53 fps for No. 2 diesel fuel depending on slick thickness. For practical purposes, earlier experiments have shown that this initial small oil loss by droplet entrainment can be tolerated up to a higher velocity of about 1.0 fps where substantial oil loss occurs.

Commentary by Dr. Valentin Fuster
J. Basic Eng. 1972;94(4):879-884. doi:10.1115/1.3425581.

Linearized theory for wave-making resistance is applied to semisubmerged ships. Theoretical and experimental values are compared for submerged hulls, struts, and struts in tandem. Strut forms producing minimum wave-making resistance are calculated at several speeds and water plane areas for a typical submerged hull. Struts are described in terms of step functions to facilitate an investigation of multiple struts including the effect on drag of decreased wetted surface area.

Commentary by Dr. Valentin Fuster
J. Basic Eng. 1972;94(4):885-892. doi:10.1115/1.3425582.

Radius and interference design parameters of elastic, multilayer, thick-walled cylindrical vessels are optimized on the basis of the Mises distortion energy yield criterion. Loadings are assumed uniform along cylinder length and may be independently applied or combined internal pressure and steady-state axiallysymmetric thermal gradients, as well as specified initial stresses to simulate autofrettage or other residual stresses. The optimization is effected by an accelerated, steepest-ascent, gradient projection method, subjected to constraints on loaded stress intensity, shrink stress intensity, end loading, tangential stress (e.g., for a brittle liner), and monotonic-decreasing interface pressures. Independent elastic and thermal properties are allowed for each layer; however, time-dependent phenomena are not considered. The general procedure developed is compared with several published optimization solutions for various special cases.

Commentary by Dr. Valentin Fuster
J. Basic Eng. 1972;94(4):893-896. doi:10.1115/1.3425583.

The author reviews methods of calibrating low-differential (25–300 in. H2 O) D.P. transmitters at high (up to 3000 psig) static pressure. Various test methods are described along with discussion of their merits. Included are use of one or more deadweight testers (gas or liquid) and use of a high-pressure mercury manometer as a standard. Five D.P. transmitters of different construction are tested and their static span-shift performance reported.

Commentary by Dr. Valentin Fuster
J. Basic Eng. 1972;94(4):897-903. doi:10.1115/1.3425584.

Despite intensive research into laminarization over the past twenty years, there has resulted hitherto no prediction method suitable for ab intio engineering design applications. Following a critical survey of currently proposed prediction criteria, this paper presents experimental evidence for a new prediction scheme applicable for the first time to compressible adiabatic flows. It is shown that this scheme is readily applicable for engineering design purposes. Extension to nonadiabatic flows is discussed.

Commentary by Dr. Valentin Fuster
J. Basic Eng. 1972;94(4):905-911. doi:10.1115/1.3425588.

Head injury is often attributed to transient shear stresses arising from rotation of the brain in the cranial cavity. This paper deals with the experimental determination and analytical characterization of in vitro human brain dynamic constitutive properties in pure shear. A closed loop, feedback torsional system with a self mass cancelling torque transducer is used for the experimental study. Values of the storage and loss components of the dynamic shear modulus are computed and a four parameter, linear, visco-elastic model representing brain tissue properties up to 350 Hz is presented. In addition, failure criterion in terms of limiting strains and strain rates are identified.

Commentary by Dr. Valentin Fuster
J. Basic Eng. 1972;94(4):912-916. doi:10.1115/1.3425589.

A practical technique was developed for in vivo determinations of the mechanical properties of canine left ventricle. A “quick stretch” was accomplished by rapid injection of isotonic saline into the ventricle during isovolumetric systole. The experimental pressure-volume data and a stress-strain analysis of the left ventricle as a thick-walled sphere permitted determination of the effective elastic modulus as a function of the mean circumferential stress. The elastic modulus E was found to be a linear function of the mean tangential stress σ throughout the isovolumetric systolic period; the slope (K, modulus of stiffness) of the Eversus σ curve was 18.8 with a standard deviation of 0.9.

Commentary by Dr. Valentin Fuster
J. Basic Eng. 1972;94(4):917-925. doi:10.1115/1.3425590.

For model tests on cavitation inception, the knowledge of the size distribution and frequency of occurrence of free nuclei is important. For this reason, an optical measuring method was developed for determining the bubble nuclei spectrum. In conjunction with measuring the bubble nuclei spectrum, a set of tests on cavitation inception was carried through, with each test leading basically to the same conclusions: The number and size of the bubble nuclei in water are dependent on the history of the particular water and on its content of contamination particles; the cavitation inception at a submerged body is strongly affected by the bubble nuclei content.

Commentary by Dr. Valentin Fuster
J. Basic Eng. 1972;94(4):926-930. doi:10.1115/1.3425591.

Despite the widespread use of convergent-conical nozzles as propulsion nozzles in turbojet aircraft, little attention has been given to the effect of nozzle shape on their propulsive performance. This paper presents the results of an experimental investigation in which the effect of nozzle angle on the internal characteristics of the flow field and on the propulsive performance of convergent conical nozzles was investigated. In addition, a theoretical solution is described which was developed as a part of this investigation. Fifteen, twenty-five, and forty-degree nozzles were tested at pressure ratios from 1.4 to 7.0. Measurements were made of the nozzle discharge coefficient, thrust coefficient, local flow angle, and wall static pressure. The properties of the internal flow field were seen to be affected by the nozzle angle and at pressure ratios less than the choked pressure ratio by the pressure ratio as well. The results of the theoretical analysis substantiate this behavior and are in reasonable agreement with the experimental data.

Commentary by Dr. Valentin Fuster
J. Basic Eng. 1972;94(4):933-940. doi:10.1115/1.3425596.

Interaction of an individual vapor bubble formed by a spark gap in water at room temperature with a neighboring air bubble, such as could have significance in cavitation, was investigated using high speed photography. Air bubbles were located both on and far from boundaries. An air bubble located on the solid boundary was able to protect the surface from damage. Two effects of the interaction which appeared to be important in the damage prevention were energy transfer from the vapor bubble to the gas bubble and repulsion of the vapor bubble by the gas bubble. Gas bubbles far from boundaries absorbed less energy and had less repulsive effect than those on solid boundaries.

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

TECHNICAL BRIEFS

J. Basic Eng. 1972;94(4):943-945. doi:10.1115/1.3425599.

The “break spinning” process has recently been introduced to improve spinning efficiency in the textile industry. In one version, fiber elements are drawn onto the inner rim of a rapidly rotating drum from which they are pulled away, as yarn, by means of a thread inserted along the axis. The quality of the yarn produced is considered to be sensitive to the air flow in the drum. The object of this work is to apply simple rotating flow theory, to obtain the angular velocity distribution inside the drum.

Commentary by Dr. Valentin Fuster
J. Basic Eng. 1972;94(4):945-946. doi:10.1115/1.3425600.
Abstract
Commentary by Dr. Valentin Fuster

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