An apparatus for producing tunable, repeatable, hydrogen–oxygen-deflagrative blast waves

Abstract

The Hydrogen Unconfined Combustion Test Apparatus (HUCTA) was designed and built to study the blast waves produced from unconfined hydrogen/oxygen deflagrations. The HUCTA uses evacuated balloons of up to 2 m in diameter which are filled with a combustible combination of gaseous hydrogen–oxygen mixtures. The well-mixed gases are ignited with an electric spark at the center of the sphere, resulting in a gaseous deflagration propagating through the mixture and a shock wave produced in the air. The combinations of balloon size and fuel/oxidizer ratios allow for a wide range of blast waves to be produced. Overpressures are measured with standard blast gauges at a variety of locations, demonstrating a high degree of radial symmetry and repeatability in the shock wave pressures, as well as the ability to produce non-ideal shock wave pressure profiles under some conditions. The range of peak pressures and explosive impulses obtainable is described as a function of mixture ratio. High-speed retroreflective shadowgraphy is used to visualize shock wave propagation and coalescence in individual frames and digital streak images. Since HUCTA is elevated approximately 2 m off the ground, there is a significant area around the apparatus where non-noisy, un-reflected, symmetric blast waves propagate; this area is ideal for testing items whose response to blast waves is desired for safety considerations.