Techniques for Conducting Shock Tube Experiments with Mixtures of Ultrafine Solid Particles and Gases

Abstract

Techniques have been developed for conducting shock tube experiments on mixtures of fine solid particles and gases. Particles with diameters of 1 μ and smaller are prepared by grinding in a dry atmosphere. The powdered material is injected into the shock tube test section by opening a valve connecting the evacuated shock tube with a tank containing gas into which the powder has been previously suspended by a pressurized injection. The axial distribution of powder in the shock tube has been measured both by determining the weight of powder which has settled out on small stainless steel slides placed in the shock tube and by observing the optical absorption from a long-life reaction product of the shock-heated powder-gas mixture as the mixture sweeps by an observation port. Typical operating results are presented, including particle size distribution of a solid material after grinding, powder distribution along the shock tube axis after injection, and oscilloscope records of absorption at 2536 Å by the CF2 formed from Teflon decomposition behind the incident shock wave.