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RESEARCH PAPERS

J. Fluids Eng. 1978;100(3):265-274. doi:10.1115/1.3448661.

In this paper, we first present a state of the art review of the published work concerning theoretical nozzle discharge coefficients. Then, we develop a new nozzle discharge coefficient based on an axisymmetric boundary layer solution, which in turn is based on a new axisymmetric potential flow solution. These solutions apply to plenum inlet installations which offer major advantages over conventional ASME pipe inlet installations as to losses, and as to predictability of the discharge coefficient at the higher Reynolds numbers encountered in industry. Next, we present new correlations for static pressure tap errors and apply these to the theoretical (zero tap size) discharge coefficients. Finally, we present new experimental data showing how a laminar boundary layer is preserved and tap error is accordingly minimized for the case of a plenum inlet with ASME nozzle contour.

Commentary by Dr. Valentin Fuster
J. Fluids Eng. 1978;100(3):276-280. doi:10.1115/1.3448664.

A leading-edge correction is obtained via the method of matched asymptotic expansions to the first-order linearized solution for the potential flow past a supercavitating flat-plate hydrofoil at zero cavitation number. The composite expansions for the pressure on the plate and the shape of the upper cavity are seen to compare well with the exact solution due to Rayleigh.

Commentary by Dr. Valentin Fuster
J. Fluids Eng. 1978;100(3):281-286. doi:10.1115/1.3448667.

Experimental results are presented regarding the nature of the flow of a viscous incompressible fluid contained between two concentric spherical surfaces that rotate at different angular velocities. Depending upon the various parameters involved (the radius ratio, the angular velocity ratio, and the Reynolds number), the resulting flow in the spherical annulus may be laminar, turbulent, or some combination of laminar and turbulent flow. The basic laminar flow patterns are observed by use of flow visualization methods. Similarities and differences between the stability characteristics of spherical annulus flow and cylindrical annulus flow are discussed.

Commentary by Dr. Valentin Fuster
J. Fluids Eng. 1978;100(3):287-290. doi:10.1115/1.3448668.

Investigators of unsteady flows normally have little control over the waveform of the flow unsteadiness. This paper describes a programmable rotating blade damper system that is capable of producing a near sinusoidal velocity waveform without wind tunnel resonance. By varying the angular velocity of the rotating blades in a damper at various times in a cycle the desired waveform can be obtained. The amplitude and frequency of the flow oscillation are also adjustable. There is little variation of the period of the waveform and the results are highly repeatable.

Commentary by Dr. Valentin Fuster
J. Fluids Eng. 1978;100(3):291-298. doi:10.1115/1.3448669.

Measured and calculated values of the velocity characteristics of a modeled room with ventilation arrangements are reported. The measurements were obtained by laser-Doppler anemometry and the calculations by the solution, in finite-difference form, of two-dimensional, elliptic, partial-differential equations representing conservation of mass, momentum, turbulence energy and dissipation rate. The results demonstrate that the precision of calculation is adequate for design purposes although, for slots much smaller than the width of the room, three-dimensional effects become important. They quantify, for example, the extent to which a decrease in supply area leads to an increase in air velocities for a given mass flow rate.

Commentary by Dr. Valentin Fuster
J. Fluids Eng. 1978;100(3):299-307. doi:10.1115/1.3448670.

Loss characteristics of sharp-edged orifices, quadrant-edged orifices for varying edge radii, and nozzles are studied for Reynolds numbers less than 10,000 for β ratios from 0.2 to 0.8. The results may be reliably extrapolated to higher Reynolds numbers. Presentation of losses as a percentage of meter pressure differential shows that the flow can be identified into fully laminar regime, critical Reynolds number regime, relaminarization regime, and turbulent flow regime. An integrated picture of variation of parameters such as discharge coefficient, loss coefficient, settling length, pressure recovery length, and center line velocity confirms this classification.

Commentary by Dr. Valentin Fuster
Commentary by Dr. Valentin Fuster
J. Fluids Eng. 1978;100(3):311-322. doi:10.1115/1.3448672.

A series of experiments on steam condensation have been made in a Laval nozzle over a variety of starting conditions such that the onset of condensation occurs in the range −40 to 40°C (233–313 K). The homogeneous nucleation and growth of the new phase are documented with both static pressure and laser light scattering. Since even at onset the majority of the condensed phase is due to droplet growth the nucleation and growth are coupled and the availability of two measured quantities is helpful in comparing a particular combination of nucleation rate and growth law. For detailed calculations on one of the experiments there is excellent agreement with both measurements throughout the condensation zone and theoretical calculations using the classical nucleation rate expression due to Volmer and droplet growth laws due to Gyarmathy and Hill in which thermal and mass accommodation coefficients are near unity.

Commentary by Dr. Valentin Fuster
J. Fluids Eng. 1978;100(3):323-332. doi:10.1115/1.3448673.

The aerodynamic characteristics of separated, recirculating flows behind a two-dimensional nozzle and bluff-body combination, which modeled a lean mixture combustor, was explored by a series of cold flow tests. The detailed distributions of mean velocities, static pressures, turbulent characteristics, and the tracer gas steady-state concentration were obtained. The flow velocity observations were successfully obtained by use of a laser velocimeter, whose data reduction system was devised particularly for use in highly turbulent flow measurements. Overall features of the mean field data revealed that the nozzle blowing diminished the longitudinal extent of the recirculation zone and substantially affected the mixing of tracer gas with the surrounding airflow. The Reynolds stress data imply that a zone of opposing shear was formed near the region of coexistence between negative and positive mean axial-velocities.

Commentary by Dr. Valentin Fuster
J. Fluids Eng. 1978;100(3):333-338. doi:10.1115/1.3448674.

The results of an experimental investigation of the trajectory and dispersion of a solid-gas (silicate-air) jet injected into a transverse stream are presented. The centerline and the spread of the jet were defined by the particulate distribution as sampled with an isokinetic probe. The jets of this study had a solid to air mass ratio on the order of 15:1. Correlation equations obtained for the trajectory are similar to those reported in the literature for single phase jets. Equations are also obtained for plume dispersion.

Commentary by Dr. Valentin Fuster
J. Fluids Eng. 1978;100(3):340-342. doi:10.1115/1.3448677.

A two-dimensional analysis of the performance and flowfield of the Giromill is presented. The Giromill is a vertical-axis wind turbine with straight blades that are articulated to produce maximum energy extraction from the wind. It is found that the power coefficient and windwise force coefficient for the Giromill have the same limit as obtained for the horizontal-axis wind turbine. A cross-wind force is also obtained with this type of wind turbine. The cross-wind force is of second order and decreases with tip speed. Streamlines and velocity profiles are illustrated for several loading conditions.

Commentary by Dr. Valentin Fuster
J. Fluids Eng. 1978;100(3):343-349. doi:10.1115/1.3448678.

The analysis of gas-particle flows is complicated by the need to account for momentum and energy coupling between phases. The concept of regarding the particle phase as a source of momentum and energy to the gaseous phase is described and incorporated into a new computational scheme developed using conservative variables. Flow metering of gas-particle suspensions by a Venturi is analyzed to illustrate the applicability of this physico-computational model. The predicted pressure drop at the throat of the Venturi shows agreement with experimental data, establishing the capability of the model to treat the complex coupling phenomena in a physically appealing way through a convenient computational algorithm.

Commentary by Dr. Valentin Fuster
J. Fluids Eng. 1978;100(3):350-352. doi:10.1115/1.3448679.

A new method is presented which uses the steady flow availability function to analyze the efficiency with which energy can be transmitted in a pipeline. It is suggested that the availability approach can be used to compare the performance of all types of pipeline component such as bends, diffusers, etc., and their effect on the power available at the power turbine.

Commentary by Dr. Valentin Fuster
J. Fluids Eng. 1978;100(3):353-354. doi:10.1115/1.3448680.
Abstract
Topics: Hydrofoil
Commentary by Dr. Valentin Fuster
J. Fluids Eng. 1978;100(3):355-362. doi:10.1115/1.3448681.

A method for calculating quasi-one-dimensional, steady-state, two-phase dispersed droplet-in-vapor flow has been developed. The technique is applicable to both subsonic and supersonic single component flow in which normal shock waves may occur, and is the basis for a two-dimensional model. The flow is assumed to be inviscid except for droplet drag. Temperature and pressure equilibrium between phases is assumed, although this is not a requirement of the technique. Example calculations of flow in one-dimensional nozzles with and without normal shocks are given and compared with experimentally measured pressure profiles for both low quality and high quality two-phase steam-water flow.

Commentary by Dr. Valentin Fuster
J. Fluids Eng. 1978;100(3):363-366. doi:10.1115/1.3448682.

Solutions are presented for laminar flow of non-Newtonian power-law fluids. The flow configurations cover the two-dimensional plane and radial free jets, the axisymmetrical (circular) free jet, and the plane and radial wall jets. When the flow behavior index is unity, the present results agree well with those already published for the case of Newtonian fluids.

Commentary by Dr. Valentin Fuster
J. Fluids Eng. 1978;100(3):367-373. doi:10.1115/1.3448683.

A numerical solution of the unsteady laminar boundary layer equations is described for the flow due to a semi-infinite plate, sinusoidally oscillating with zero mean velocity. The plate periodically reverses its direction of motion with no net translation. The solution treats the region intermittently occupied by the plate as a thin symmetric wake. A time-centered two-step implicit finite-difference scheme was used with upwind differencing and a variable spatial grid to obtain the numerical results. Results are presented for velocity profiles and surface shear stress as a function of position and time.

Commentary by Dr. Valentin Fuster

DISCUSSIONS

Commentary by Dr. Valentin Fuster

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