High-Speed Photography of Rapid Air Currents and Shock Waves by Means of High-Frequency High-Voltage Sparks

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Publisher: SMPTE
Doc Type: Journal Article
Article Type: research-article
Abstract: The Bömelburg, Wesks and Herzog method has been perfected for practical application in wind-tunnel work with 0.8-to 20-in. sparks. A pulse transformer of nevel design permits powers up to 40 megawatis peak during each flash at up to 50,000 controlled dischesges/soc. Higher rates are possible under free-running conditions. The discharge duration is 0.3 to 1 μsec. Strobokin-controlled ultra-rapid spark discharges at 2000 to 300,000/sec are fed into the primary of a special pulse transformer whose essential component is a laminated sheet-metal core of hypersile sheets with Hostaphan insulation. A voltage of approximately 5 ko per turn on the primary winding gives a steep voltage step-up at the secondary, which with 75 turns, for example, produces a no-load voltage of 300 kv. Owing to the short spark-discharge time, no picture blue results even at air speeds of several thousand fast per second. Although the luminance of the sparks is sufficient for high-speed photography, practical experiemer shows that their low energy does not cause thermodynamic disturbance of the airflow under observation. The lowest possible spark rate where no deionization occurs is 2000/sec. At 1-mm spark spacing, this corresponds to an air velocity of 2 m/sec, whereas the maximum spark rate of 300,000/sec at 20 mm from spark to spark corresponds to an air velocity of 6 km/sec, i.e. approximately Mach 18. Also, patierns of explosion and detonation shock waves and their subsequent eddy current: can be traced by the spark method outlined above.
Publication Date: 1962-03-01
DOI: 10.5594/J16889
Link: https://doi.org/10.5594/J16889
Author(s): Frank Früngel, Walter Thorwart, H. G. Patzke

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Frank Früngel, Walter Thorwart, and H. G. Patzke; High-Speed Photography of Rapid Air Currents and Shock Waves by Means of High-Frequency High-Voltage Sparks, Journal of the SMPTE ( Volume: 71, Issue: 3, March 1962); SMPTE, 1962. Available at https://doi.org/10.5594/J16889

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Frank Früngel, Walter Thorwart, and H. G. Patzke; High-Speed Photography of Rapid Air Currents and Shock Waves by Means of High-Frequency High-Voltage Sparks, Journal of the SMPTE ( Volume: 71, Issue: 3, March 1962); SMPTE, 1962. Available at https://doi.org/10.5594/J16889

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<span class="citation">Frank Früngel, Walter Thorwart, and H. G. Patzke; <cite>High-Speed Photography of Rapid Air Currents and Shock Waves by Means of High-Frequency High-Voltage Sparks</cite>, Journal of the SMPTE ( Volume: 71, Issue: 3, March 1962); SMPTE, 1962. Available at <a href="https://doi.org/10.5594/J16889" target="_blank" rel="noopener">https://doi.org/10.5594/J16889</a></span>

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<li>
Frank Früngel, Walter Thorwart, and H. G. Patzke; <cite id="bib-10-5594-j16889">High-Speed Photography of Rapid Air Currents and Shock Waves by Means of High-Frequency High-Voltage Sparks</cite>, Journal of the SMPTE ( Volume: 71, Issue: 3, March 1962); SMPTE, 1962
<span class="doi">10.5594/J16889</span>
</li>