Shadowgraph Research Articles

Hemispherical shock wave in a laser irradiated freely falling glass microballoon

A freely falling glass microballoon filled with helium gas to 6 atm is irradiated by a focused Nd:YAG laser beam in air. A time resolved microscopic shadow graph shows hemispherical shock wave in the balloon.

X-ray micro tomography in the scanning electron microscope

Reconstructive tomography is a new technique in diagnostic radiology for imaging cross-sectional planes of the human body /1/. A collimated beam of X-rays is scanned through a thin slice of the body and the transmitted intensity is recorded by a detector giving a linear shadow graph or projection (see fig. 1). Many of these projections at different angles are used to reconstruct the body-layer, usually with the aid of a computer. The picture element size of present tomographic scanners is approximately 1.1 mm2.Micro tomography can be realized using the very fine X-ray source generated by the focused electron beam of a scanning electron microscope (see fig. 2). The translation of the X-ray source is done by a line scan of the electron beam on a polished target surface /2/. Projections at different angles are produced by rotating the object.During the registration of a single scan the electron beam is deflected in one direction only, while both deflections are operating in the display tube.

Study on Oblique Grid Shadow Graph

There are several kinds of optical methods for the measurements of temperature distribution in transparent fluids, such as the Mach-Zehnder interferometer, the Schlieren photo method, the shadow graph method etc.But the Mach-Zender interferometer needs doubled optical paths for reference, and the Schlieren method and the shadow graph have difficulty in getting exact temperature distributions although they can somehow give the maximum value of temperature gradients on the walls.The new method reported herein, which is called the oblique shadow graph, is a very simple optical technique. It is only to take pictures of an object with a grid of parallel oblique-lines in its behind.The detail of thermal structure of boundary layers, the temperature distributions, and the maximum heat flux at the walls, can be known from the deviations of grid line in the picture taken by this method.In further application, this method can measure mass transfer, measure a temperature distribution of a boundary layer even when pressure changes, and measure boiling heat transfer.

Estimation of clubbing by analysis of shadowgraph.

Estimation of clubbing by analysis of shadowgraph.

Oil Production After Breakthrough as Influenced by Mobility Ratio

Abstract The study of the influence of fluid mobilities on the sweepout pattern resulting from the injection of gas or water has been extended to cover the production period which follows breakthrough of the injected material. Mobility ratios over the range common in field operations (0.1 to 17) were studied for several pattern floods (five-spot, staggered, and direct line drive). The experimental data required for these studies were obtained by the use of the x-ray shadow graph technique using miscible oil phases of different viscosities in porous plate models of a reservoir element. From the shadowgraph pictures obtained before and after breakthrough of the injected fluid, flowing ratios at the producing well and cumulative volumes injected were calculated. The method for applying such data in predicting field behavior is illustrated for a water flood of a five-spot. For this case a range of mobility ratios of 0.5 to 5.0 results in:nearly complete (95 to 100 per cent) sweepout pattern efficiencies at abandonment conditions,production after breakthrough being responsible for as much as one-third of the total recovery at the lower mobility ratios, anda twofold variation in the operating life of the reservoir.

The Wehnelt Current Interrupter

IN reference to the Wehnelt current interrupter—in 1874 I used a similar interrupter on a coil with fifty Groves' cells. The idea was not even then new, for although my experiment was due to accidental short-circuiting of electrodes during electrolytic experiments, which led to my final application of the so-called interrupter as a resistance to current, and then as a rapid make-and-break, I found that some of the old masters of electrics had evidently used it before. Since November 1896, I have always endeavoured in using a Jackson tube to condition the tube by heating, when connected with coil, so that the make-and-break of coil shows infinitesimal sparking and works with such rapid vibrations that a musical note is produced, the pitch varying as the position of the flame heating the tube is altered. Shadow graphs can then be obtained of the human trunk from thirty-five seconds upwards, and the results on English fluorescent screens are almost perfect. This has all been mentioned in my lectures at the Royal Artillery Institute, &c., the first being at the end of October 1896.