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IN MEMORIAM

J. Fluids Eng. 1982;104(3):274. doi:10.1115/1.3241829.
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Abstract
Commentary by Dr. Valentin Fuster

REPORTS

J. Fluids Eng. 1982;104(3):275-276. doi:10.1115/1.3241830.
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Commentary by Dr. Valentin Fuster
J. Fluids Eng. 1982;104(3):276-277. doi:10.1115/1.3241831.
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Abstract
Commentary by Dr. Valentin Fuster
J. Fluids Eng. 1982;104(3):277-278. doi:10.1115/1.3241832.
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Abstract
Commentary by Dr. Valentin Fuster

REVIEW ARTICLES

J. Fluids Eng. 1982;104(3):279-283. doi:10.1115/1.3241833.

Two-phase flow is an “insecure” science. Many factors influence the phenomena, limiting the value of theory unless supported and guided by observation. Several methods of analysis are available; they should be used carefully and often need to be adapted in an “ad hoc” way to solve particular problems. Current efforts are concentrated on the separated (two-fluid) theoretical model and the development of improved instrumentation.

Commentary by Dr. Valentin Fuster
J. Fluids Eng. 1982;104(3):284-296. doi:10.1115/1.3241834.

The present paper describes combined laser Doppler particle sizing systems which permit simultaneous velocity and size measurements of individual particles. Combined measurements of these properties are achieved by extended laser Doppler anemometers. These extensions require the physics of laser Doppler signal generation to be clarified. A system for measurements of small particles and one to measure the properties of large particles is described. Some applications of these instruments are given.

Commentary by Dr. Valentin Fuster
J. Fluids Eng. 1982;104(3):297-303. doi:10.1115/1.3241835.

The rapidly increasing capability of computers has led to the development of numerical models for gaseous flows and, in turn, gas-particle and gas-droplet flows. This paper reviews the essential features of gas-particle flows from the point of view of model development. Various models that have appeared for one-dimensional and two-dimensional flows are discussed. The advantages and disadvantages of the trajectory and two-fluid models are noted.

Commentary by Dr. Valentin Fuster

RESEARCH PAPERS

J. Fluids Eng. 1982;104(3):304-311. doi:10.1115/1.3241836.

A general analysis of gas-particle flows, under the hypotheses of number of particles large enough to consider the solid phase as a continuum and of volume fraction small enough to consider the suspension as dilute, is presented. The Stokes number Sk and the particle loading ratio β are shown to be the basic parameters governing the flow. Depending on the values of these two parameters, in one case the reciprocal interaction of the fluid and solid phases must be considered (two-way coupling), in the second case only the effect of the fluid field on the particle motion is relevant (one-way coupling). In the more general case of two-way coupling, the flow is governed by two sets of Navier-Stokes equations, one for each phase, which are coupled together through the particle volume fraction and the momentum interchange forces. The two systems of equations, expressed in the variables velocity, pressure, and particle volume fraction, are solved numerically by a finite difference scheme. The model has been applied to a duct with a sudden restriction, simulating a flow metering device. The coupling effect both on fluid and solid phase fields, the increase of pressure drop, and the energy dissipated in the fluid-solid interaction have been determined as functions of the governing parameters, Sk and β. The parametric study also indicates the ranges of β and Sk in which simplified formulations may be assumed.

Commentary by Dr. Valentin Fuster
J. Fluids Eng. 1982;104(3):313-317. doi:10.1115/1.3241839.

Plume shape, vaporization, droplet-size distribution, and number density of a solid-cone fuel spray were studied with both conventional and novel measurement techniques. Minor differences in spray plume shape were observed by measurements with photography, pulsed laser shadowgraphy, and in-line infrared spectroscopy. Laser Mie scattering showed the dispersion of small numbers of droplets beyond spray boundaries as determined by other measurements. A new optical method for nonintrusive, local, time-averaged measurement of vapor concentration, droplet-size distribution and number density within an axisymmetric spray is introduced. For the spray studied this method showed that vapor is confined to the spray plume and that vapor concentration and the concentration of small-diameter droplets exhibit analogous behavior.

Commentary by Dr. Valentin Fuster
J. Fluids Eng. 1982;104(3):318-325. doi:10.1115/1.3241840.

Pipe vibrations can be induced by internal liquid pulsations which propagate throughout the piping system and create unbalanced oscillatory pressure forces at locations where either flow area or direction changes. The fluid motion is set up by a source of mechanical excitation or flow instability. Dynamic interaction of the liquid and piping may be modelled by separate analyses of liquid and solid components followed by synthesis of the component solutions. In contrast to other formulations that correctly represent interaction, the technique presented herein has the computational advantage of decomposing the anaysis into steps. The most time-consuming step is structural analysis, which may be delegated to existing, efficient computer algorithms. The synthesis method is outlined, the advantages discussed and application illustrated with numerical examples.

Commentary by Dr. Valentin Fuster
J. Fluids Eng. 1982;104(3):326-333. doi:10.1115/1.3241841.

Measurements of the pressure distributions on the three-dimensional bluff bodies are correlated with the characteristics of the smooth-wall turbulent boundary layers in which the bodies are immersed. The bluff bodies selected for measurement were a cube and a vertical circular cylinder which can be considered as typical examples of three-dimensional bluff bodies. Experimental data were collected to investigate the effects of (1) the variation of the height of bluff bodies h, (2) the characteristics of the smooth-wall boundary layers in which they are immersed, on the form drag acting on the three-dimensional bluff bodies. For flow with zero-pressure gradient, the form drag coefficients of the cube and the vertical circular cylinder defined by CDτ =D/(1/2ρuτ 2 h2 ) are found to be expressed as a power-law function of huτ /ν in the range of h/δ less than about 1.0, where D is the form drag, uτ the shear velocity, ν the kinematic viscosity and δ the thickness of the undisturbed boundary layer at the location of the bluff bodies. For h/δ>1.0, the drag coefficients are independent of the parameter uτ /U0 , being uniquely related to h/δ. Further, the pressure distributions along the front centerline of each bluff body can be expressed by a single curve irrespective of both the height of the bluff body and the boundary layer characteristics and show a good agreement with the dynamic pressure in an undisturbed boundary layer at the location of the bluff bodies in the range of about 0.2<y/h<0.7, where y is the distance from the wall.

Commentary by Dr. Valentin Fuster
J. Fluids Eng. 1982;104(3):335-341. doi:10.1115/1.3241845.

Basic relations and method of solution are given for laminar transient flows in linear viscoelastic circular fluid transmission lines. Using a numerical method to invert the Laplace-Carson transforms, basic step response plots are given for semi-infinite liquid-lines. The method can be immediately applied to any practical problem with linear or explicitly time dependent boundary conditions. Analytical expressions are given for the behavior at the wave front and for large values of time. Also derived are classical parameters characterizing the frequency response.

Commentary by Dr. Valentin Fuster
J. Fluids Eng. 1982;104(3):342-347. doi:10.1115/1.3241846.

This paper presents a summary of the general behavior of cylinder clusters in axial flow and especially of the fluidelastic instabilities which occur at high flow velocities. Experiments were conducted in a water tunnel with three- and four-cylinder clusters, and the behavior was monitored either optically or by instrumenting one of the cylinders with strain gauges. With increasing flow, the amplitude of small random vibrations of the cylinders increased; simultaneously, the natural frequencies, as a group, decreased, which is in good agreement with theory. The cylinders eventually lost stability by buckling (divergence), and at higher flow by flutter. Agreement between theoretical and experimental critical flow velocities for these fluidelastic instabilities has been found to be good.

Commentary by Dr. Valentin Fuster
J. Fluids Eng. 1982;104(3):350-359. doi:10.1115/1.3241850.

Two orthogonal components of velocity and associated Reynolds stresses have been measured in a square-sectioned, 90 degree bend of 2.3 radius ratio using laser-Doppler velocimetry for Reynolds numbers of 790 and 40,000. The boundary layers at the bend inlet were 0.25 and 0.15 of the hydraulic diameter and resulted in secondary velocity maxima of 0.6 and 0.4 of the bulk flow velocity respectively. Comparison with fully-developed inlet flow shows that the boundary layer thickness is important to the flow development (mainly in the first half of the bend), particularly so when it is reduced to 0.15 of the hydraulic diameter. Turbulent flow in an identical duct with a radius ratio of 7.0 gives rise to smaller secondary velocities than in the strongly curved bend, although their effect is more important to the streamwise flow development because of the smaller pressure gradients. The detail and accuracy of the measurements make them suitable for evaluation of numerical techniques and turbulence models. Partially-parabolic techniques are applicable to the flows studied and their reduced storage requirements seem essential if satisfactory numerical accuracy is to be achieved.

Commentary by Dr. Valentin Fuster
J. Fluids Eng. 1982;104(3):360-362. doi:10.1115/1.3241851.

Simple solutions are presented for the equation governing one-dimensional flow of very viscous jets that issue from a round orifice and fall against a flat plate. Due to the viscous axial stresses developed, the jet may be either in tension or compression, depending on the values of various dimensionless parameters involved. The comparison of the theoretical and experimental results is good.

Commentary by Dr. Valentin Fuster
J. Fluids Eng. 1982;104(3):363-366. doi:10.1115/1.3241852.

The authors report measurements of azimuthal velocity versus radius in a partially-filled horizontally rotating cylinder. These data confirm theoretical calculations for laminar flow. Three nonlaminar flow states are described and a map shows boundaries separating the laminar state, and two of the nonlaminar states, in a two parameter space.

Commentary by Dr. Valentin Fuster
J. Fluids Eng. 1982;104(3):367-372. doi:10.1115/1.3241853.

Measurements of time-mean velocity, of longitudinal, normal and lateral velocity fluctuation intensities (u′ , v′ , w′ ) and of shear stress have been made for four cases of pure shear flow in a flat channel, one of whose walls is stationary while the second moves. Both walls are effectively smooth. General expressions for the mean velocity profile and a prediction of the friction coefficient are developed. Comparisons of the experimental results with existing data are made. The profiles of v′ , w′ , turbulence kinetic energy and production of turbulence energy across the channel are the first to be published.

Commentary by Dr. Valentin Fuster
J. Fluids Eng. 1982;104(3):373-377. doi:10.1115/1.3241854.

An indirect similarity-law characterization method is presented for any arbitrary irregular roughness covering a circular disk. Formulas are presented for converting the measured torques and rotary speeds of this rough rotating disk into appropriate local values at the disk edge required for the characterization.

Commentary by Dr. Valentin Fuster
J. Fluids Eng. 1982;104(3):378-384. doi:10.1115/1.3241855.

Combustor modeling has reached the stage where the most useful research activities are likely to be on specific sub-problems of the general three-dimensional turbulent reacting flow problem. The present study is concerned with a timely fluid dynamic research task of interest to the combustor modeling community. Numerical computations have been undertaken for a basic two-dimensional axisymmetric flowfield which is similar to that found in a conventional gas turbine combustor. A swirling nonreacting flow enters a larger chamber via a sudden or gradual expansion. The calculation method includes a stairstep boundary representation of the expansion flow, a conventional k-ε turbulence model and realistic accommodation of swirl effects. The results include recirculation zone characterization and predicted mean streamline patterns. In addition, an experimental evaluation using flow visualization of neutrally-buoyant helium-filled soap bubbles is yielding very promising results. Successful outcomes of the work can be incorporated into the more combustion- and hardware-oriented activities of gas turbine engine manufacturers, including incorporating the modeling aspects into already existing comprehensive numerical solution procedures.

Commentary by Dr. Valentin Fuster
J. Fluids Eng. 1982;104(3):385-391. doi:10.1115/1.3241856.

This paper describes a computer code for calculating the flow dynamics of constant density flow in the second stage trumpet shaped nozzle section of a two stage MHD swirl combustor for application to a disk generator. The primitive pressure-velocity variable, finite difference computer code has been developed to allow the computation of inert nonreacting turbulent swirling flows in an axisymmetric MHD model swirl combustor. The method and program involve a staggered grid system for axial and radial velocities, and a line relaxation technique for efficient solution of the equations. Turbulence simulation is by way of a two-equation κ-ε model. The code produces as output the flowfield map of the nondimensional stream function, axial, and swirl velocity. Good argeement was obtained between the theoretical predictions and the qualitative experimental results. The best seed injector location for uniform seed distribution at combustor exit is with injector located centrally on the combustor axis at entrance to the second stage combustor.

Commentary by Dr. Valentin Fuster
J. Fluids Eng. 1982;104(3):393-398. doi:10.1115/1.3241859.

Although a number of inviscid numerical methods have been developed for the calculation of three-dimensional transonic flow in turbomachinery blade passages it is often difficult to compare the results of these calculations directly with experiment. For instance in real machines the overall flow is very complex and it is usually impossible to model the full geometry of the machine, thus it is difficult to trace the sources of the discrepancies which inevitably arise between the measured and calculated results. Even in simpler test cases the experimental results are often strongly affected by viscous effects and flow separations. This paper presents the results of an experimental investigation which generates three-dimensional transonic flow with shock waves using relatively simple geometries and where the influence of viscous effects has been reduced as far as possible. Comparisons with the output of various calculation methods show that even with these simple geometries it is essential to use fully three-dimensional methods to predict the flow development.

Commentary by Dr. Valentin Fuster

DISCUSSIONS

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

ERRATA

TECHNICAL BRIEFS

J. Fluids Eng. 1982;104(3):400-401. doi:10.1115/1.3241863.
Abstract
Topics: Jets
Commentary by Dr. Valentin Fuster

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