Paper N–2: 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: orig-research
Abstract: The Bömelburg, Weske and Herzog method has been perfected for practical application in wind-tunnel work with 0.8-to 20-in, sparks. A pulse transformer of novel design permits powers up to 40 megawatts peak during each flash at up to 50,000 controlled discharges/sec. 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 kv 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 blur results even at air speeds of several thousand feet per second. Although the luminance of the sparks is sufficient for high-speed photography, practical experience shows that their low energy does not cause thermodynamic disturbance of the airflow under observation. The louest 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, patterns of explosion and detonation shock waves and their subsequent eddy currents can be traced by the spark method outlined above.
Publication Date: 1962-01-01
DOI: 10.5594/J18185XY
Link: https://doi.org/10.5594/J18185XY
Author(s): Frank Frungel, Walter Thorwart, H. G. Patzke

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Frank Frungel, Walter Thorwart, and H. G. Patzke; Paper N–2: 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: 1A, 1962); SMPTE, 1962. Available at https://doi.org/10.5594/J18185XY

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Frank Frungel, Walter Thorwart, and H. G. Patzke; Paper N–2: 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: 1A, 1962); SMPTE, 1962. Available at https://doi.org/10.5594/J18185XY

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<span class="citation">Frank Frungel, Walter Thorwart, and H. G. Patzke; <cite>Paper N–2: 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: 1A, 1962); SMPTE, 1962. Available at <a href="https://doi.org/10.5594/J18185XY" target="_blank" rel="noopener">https://doi.org/10.5594/J18185XY</a></span>

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<li>
Frank Frungel, Walter Thorwart, and H. G. Patzke; <cite id="bib-10-5594-j18185xy">Paper N–2: 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: 1A, 1962); SMPTE, 1962
<span class="doi">10.5594/J18185XY</span>
</li>