High-energy (Mach 130) air-shock propagation in steel and grout pipes

Voitenko compressors have been used to generate approx. 45-mm/..mu..s air shocks in a steel and a grout outlet pipe. Fiber-optic ports were used to measure diaphragm burst times and time-of-arrival data for shock-front luminosity along the 20-mm-ID exit pipes. Pressure profiles were obtained at higher enthalpy shock propagation than ever before and at many locations along the tubes. The grout experiment is the first laboratory attempt to study air shock propagation in a pipe with this type of compressible wall material. The primary purpose of these two experiments was to examine the effect of wall material on high-energy shock propagation. In the interval between 0.10 and 2.50 m from the diaphragm, the velocity and peak pressure of the shock front attenuated from approx. 45 to approx. 5 mm/..mu..s and from approx. 3.5 to approx. 0.02 GPa, respectively. Over this distance, the shock propagation was nearly identical in both experiments. The rapid attenuation of the shock front velocity and pressure is attributed to ablation and entrainment of wall material. An interesting feature, confirmed by multiple measurement techniques, was a rapid oscillation in the pressure profiles. The results indicate that, for the materials considered, shock propagation is independent of wall composition overmore » the 2.5-m length of the outlet pipes.« less