Experiments for the Measurement of the Acoustic Impedance of a Burning Solid Propellant.
Abstract
The methods of calculation for measurement by the Mawardi method of specific acoustic impedance ratio of passive samples under pressure in chambers with exhaust ports are reviewed. Equations developed for the calculation of impedances from measurements made under pressure in bodies with holes have been checked against the same measurement made in solid bodies and found to give good agreement in the frequency range 500 2000 cps. The exhaust port area provided in the chamber now in use (0.0984 sq in.) is insufficient to hold the pressure differential which accompanies propellant sample combustion within the tolerance of the microphone. An increase in the exhaust port area will be necessary to handle full size samples. Tests were made with samples which have only one half the burning surface area of the regular samples, and give a tolerable pressure differential. Studies of the propellant combustion noise with such samples showed that both the broad spectrum noise and 1000 cycle component of it are of moderate intensity and must be dealt with if significant acoustic impedance measurements are to be obtained. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Sep 18, 1962
- Accession Number
- AD0284888