High-energy air shock study in a grout pipe

A modified Voitenko compressor generated a 43 mm/..mu..s air shock in a 20-mm-i.d. 3.0 m. long pipe containing ambient atmospheric air. The first 0.15 m of outlet pipe was constructed of steel and the last 2.85 m of DR-1 grout. Between 0.10- and 2.5-m from the diaphragm the velocity of the shock front attenuated from 43- to 4.5-mm/..mu..s and peak pressure from 2.28- to 0.024 GPa. The rate of wall expansion uniformly decreases and asymptotically approaches an apparent final radius between 60-100 ..mu..s behind the shock front. Plasma flow measurements indicated a flow velocity of 27.4 mm/..mu..s and a magnetic Reynolds number >60. Wall expansion was <1 mm at the end of the pipe indicating significant attenuation of the shock front between 2.5 m and 3.0 m. 13 refs., 13 figs., 1 tab.