Showing papers in "Journal of Basic Engineering in 1972"
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TL;DR: In this paper, the effect of evaporation on the interfacial gravity wave between two fluids is studied when there is a temperature gradient in the fluids and it is found that the thermal effect is closely related to the phase transformation across the interface.
Abstract: The effect on the interfacial gravity wave between two fluids is studied when there is a temperature gradient in the fluids. It is found that the thermal effect is closely related to the phase transformation across the interface. The interfacial conditions with mass flow are first derived. Then the dispersion relation for the interfacial wave is obtained. It is found that the effect of evaporation is to damp the interfacial wave and to enhance the Rayleigh-Taylor instability. It is also found that the system will be stabilized or destabilized depending on whether the vapor is hotter or colder than the liquid.
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TL;DR: In this article, the growth of planar jets is studied using the hydrogen bubble technique of flow visualization and the generation of streaklines and timelines permit characterization of the process of vortex formation and coalescence.
Abstract: : The growth of planar jets is studied using the hydrogen bubble technique of flow visualization. Flows which are initially laminar and initially turbulent at the nozzle exit are considered. Generation of streaklines and timelines permit 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. (Author)
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TL;DR: In this article, the cavitation damage was studied for several materials over a range of temperatures in the cavitating liquid from 0 C to 90 deg C. The cavitating liquids used were distilled water, distilled water buffered to pH 8, and a 3 percent solution of NaCl in distilled water.
Abstract: Cavitation damage is studied for several materials over a range of temperatures in the cavitating liquid from 0 C to 90 deg C. The cavitating liquids used were distilled water, distilled water buffered to pH 8, and a 3 percent solution of NaCl in distilled water. The cavitation damage was produced by continuous oscillation of the test specimens with a magnetostrictive transducer so that long term chemical effects tended to be suppressed. It is found that the maximum in the damage rate occurs at temperatures in the range 40 C to 50 deg C. The decrease in the damage observed at the higher temperatures is to be expected as a consequence of the increase in vapor pressure. The rise in damage at the lower temperatures has a less obvious interpretation and may be due to an increase in chemical activity with temperature.
53 citations
TL;DR: In this paper, the effect of ejecting additive solutions from a slot into a pure-water boundary layer on a flat plate has been systematically studied, and the authors draw conclusions on the additive requirement in external flows and on the ejection technique for an optimum drag reduction.
Abstract: 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.
TL;DR: In this article, a low-temperature study of the behavior of PRESTRESSED Notched Bars has been conducted, where the authors found that the level of stress was typically below the pre-presteress level, due to the reverse-plastic flow at the notch level.
Abstract: THE LOW-TEMPERATURE FRACTURE BEHAVIOR OF PRESTRESSED NOTCHED BARS HAS BEEN STUDIED. THE FRACTURE STRESS WAS GENERALLY BELOW THE PRESTRESS LEVEL OWING TO THE INFLUENCE OF REVERSE PLASTIC FLOW AT THE NOTCH TIP ON UNLOADING. WHEN REVERSE PLASTIC FLOW WAS PREVENTED, LOW-TEMPERATURE FRACTURE OCCURRED AT STRESS LEVELS IN EXCESS OF THE PRESTRESS LEVEL. THE BENEFITS OF PRESTRESSING ARE INTERPRETED IN TERMS OF THE INTRODUCTION OF PLASTIC ZONES RATHER THAN THE INFLUENCE OF RESIDUAL STRESSES. THE INFLUENCE OF AGING AND HIGHER STRAIN RATES ON THE FRACTURE BEHAVIOR OF PRESTRESSED SPECIMENS IS ALSO STUDIED. /AUTHOR/
TL;DR: In this article, a simple mathematical analog for determination of the squeeze film behavior between two parallel annular disks, one having a porous facing, from the already available solutions of comparable nonporous disks is presented.
Abstract: A simple mathematical analog for determination of the squeeze film behavior between two parallel annular disks, one having a porous facing, from the already available solutions of comparable nonporous disks is presented. A comparison of the analog solution with a Fourier-Bessel solution has been made and the agreement is found to be good for a range of values of the permeability parameter and the porous facing thickness. The results also have been extended to include the rotating inertia effect of the film fluid. The resulting dimensionless pressure distribution and the dimensionless squeeze film load are expressed in terms of a permeability parameter, inertia parameter, squeeze film number, and the disk dimensions. For constant squeeze film load, a relationship between squeeze time and film thickness also has been obtained. Generally, the presence of the porous facing will decrease the squeeze film load and will reduce the total squeeze time to some finite value. The inertia effect will further decrease the squeeze film load and the squeeze time, however, the squeeze time reduction due to the inertia effect will become small if the porous facing has high permeability and is thick.
TL;DR: In this article, 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.
Abstract: 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.
TL;DR: The finite element technique has been applied in the analysis of a variety of pressure vessel problems as discussed by the authors, and the example problems described in this paper suggest that the finite element method is perhaps the most suitable means currently available for obtaining quick and accurate solutions for real-life pressure vessel problem.
Abstract: The finite-element technique has been applied in the analysis of a variety of pressure vessel problems. The example problems described in this paper suggest that the finite-element method is perhaps the most suitable means currently available for obtaining quick and accurate solutions for real-life pressure vessel problems. Finite-element programs can be used by the practicing engineer. Companion programs are available that can be used to check the input data and graphically display both the input and output data.
TL;DR: In this paper, the authors investigated turbulent flow in both smooth and rough-walled pipes for Reynolds number from 30,000 to 480,000, and showed that these equations can be satisfied by the experimental data if secondary flows and angular variations in the mean velocity are postulated.
Abstract: Fully developed turbulent flow in both smooth and rough-walled pipes is investigated for Reynolds number from 30,000 to 480,000. The values of mean velocity, root-mean-square values of the fluctuating velocity components, and cross-correlation values of the fluctuating velocities are presented for flow in a smooth pipe and two sand roughened pipes. Differences between smooth and rough pipe results, suggests that the accepted reduction of the Reynolds equations for flow in smooth pipes is not valid for flow in rough pipes. Thus, the Reynolds equations are re-examined for flow in rough pipes, and it is shown that these equations can be satisfied by the experimental data if secondary flows and angular variations in the mean velocity are postulated.
TL;DR: In this article, the influence of yaw angle on circular cylinder pressure drag and wake characteristics in the range of free-stream Reynolds numbers 5000 to 20,000 was evaluated and it was found that the transition from laminar to turbulent motion was significantly promoted as the yaw increased.
Abstract: : Experiments were performed to evaluate the influence of yaw angle on circular cylinder pressure drag and wake characteristics in the range of free-stream Reynolds numbers 5000 to 20,000. 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 shear wave or transition frequency do not obey the independence principle which requires that properties be dependent only on the normal component of the freestream conditions. (Author)
TL;DR: In this article, the authors proposed a technique for the analysis of free surface motions with fixed boundaries and up to three free surfaces, which can solve two-dimensional rectangular or axisymmetric problems.
Abstract: Pressure and acceleration-induced distortion of an incompressible, inviscid liquid region is predicted numerically. The liquid is bounded by both fixed and free boundaries, and its motion is irrotational. Normal velocity is prescribed on fixed, though perhaps permeable boundaries, and the starting velocity potential is given on all free surfaces. Distortions of the liquid region are described by the motion of discrete kinematic markers assigned to each free surface. Problems are formulated on a square mesh computation field in terms of velocity potential. The liquid region interior is solved numerically by overrelaxation at every time step, which permits velocity components and potential rates to be calculated at the free surfaces. Marker positions and potentials are advanced each time step, thus preparing the computation field for further overrelaxation, and the process is repeated until finished. This technique was formulated as a Fortran IV computer program, FREESURF, for studying free surface motions. The technique can solve two-dimension rectangular or axisymmetric problems with fixed boundaries and up to three free surfaces. Bubble expansion and collapse near a free surface, dam break flows, draining of a tank, and other similar problems can be predicted with the method.