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The Measurement of High Speed Air Velocity and Temperature using Sound Wave Photography

Published online by Cambridge University Press:  07 June 2016

D. E. Elliott
D. E. Elliott*
Affiliation:
Liverpool University*
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Summary

A transient sound wave is generated by discharging a spark in an air stream, the velocity and temperature of which are required. After a time interval of about 25 microseconds a shadowgraph photograph of the sound wave is taken; a second photograph is obtained after a further known time interval of the same order. The two exposures, both on the same negative, show the propagation of the sound wave in the air stream and from this the Mach number, the true velocity, the local velocity of sound, and hence the temperature, can be calculated.

Using this method, measurements of Mach numbers of the order of 0·5 gave values between 98 per cent, and 100 per cent, of those calculated from pressure measurements. Typical examples of the sound wave photographs are shown. With further development along the lines indicated in the paper greater accuracy should be possible. The local speed of sound was measured to an estimated accuracy of ±1·5 per cent.

Since only a very short time interval is needed to obtain the photographs, the method appears promising for investigating explosions of brief duration, or dealing with flows of pulsating character.

Type
Research Article
Information
Aeronautical Quarterly , Volume 6 , Issue 3 , August 1955 , pp. 181 - 195
Copyright
Copyright © Royal Aeronautical Society. 1955

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References

1. Carrier, G. F. and Carlson, F. D. On the Propagation of Small Disturbances in a Moving Compressible Fluid. Quarterly of Applied Mathematics, Vol. IV, No. 1, April 1946.Google Scholar
2. Chaney, N. K., Hamister, V. C. and Glass, S. W. The Properties of Carbon at the Arc Temperature. Transactions of the Electrochemical Society, Vol. 57, p. 107, 1935.Google Scholar
3. Eisenstein, J., Clark, K. C. and Carlson, F. D. Sonic True Airspeed Indicator. Office of Scientific Research and Development Report No. 5369, August 1945.Google Scholar
4. Foley, A. L. and Souder, W. H. A New Method of Photographing Sound Waves. The Physical Review, Vol. XXXV, p. 373, 1912.Google Scholar
5. Keenan, P. C. and Polachek, H. The Measurement of Density and Shock Waves by Shadowgraph Method. U.S. Navy Department, Bureau of Ordnance, Washington, D.C. Navord Report 86-46, September 1946.Google Scholar
6. Koenig, R. J. and Cesaro, R. S. Investigation of Spark-Over Voltage-Density Relation for Gas-Temperature Sensing. N.A.C.A. T.N. 2090(3), August 1950.Google Scholar
7. Marlow, D. G., Nisewanger, C. R. and Cady, W. M. Instantaneous Measurement of Velocity and Temperature in High Speed Air Flow. Journal of Applied Physics, 20th August 1949.Google Scholar
8. Melton, B. S., Prescott, R. and Gayhart, E. L. A Working Manual for Spark Shadow graph Photography. Johns Hopkins University, Applied Physics Laboratory, Bumblebee Series Report No. 90, December 1948.Google Scholar