An experimental study of the explosion generated by a pressurized sphere

Abstract

An experimental investigation of the explosions of 2 in. diameter glass spheres under high internal pressure has been made. The spheres were initially filled with air or helium at 400 and 326 p.s.i., respectively, and were exploded in air at atmospheric pressure. Experiments on the simulation of high-altitude explosions are also described. Schlieren and spark shadowgraph records of explosion phenomena, and pressure records of the reflexion of the spherical shock wave at various radii, are presented.An account of some initial experiments on the implosion of 5 in. diameter glass spheres is given. The results were not very satisfactory because of the failure of the spheres to shatter in a desirable manner while under an external pressure of 65 p.s.i.Numerical solutions to the air and helium sphere explosions are described and the experimental wave phenomena are shown to be in good quantitative agreement with the theoretical predictions, in that they exhibit all the main features that were predicted and are modified only by the physical limitations of the glass diaphragm. A formation process is associated with the spherical shock waves in practice, resulting in initial shock velocities which are lower than the theoretical values.

Analysis of mixing in high-explosive fireballs using small-scale pressurised spheres

“…The sphere indeed shattered differently than in the other tests and produced larger debris. Figure 14 presents the wave diagrams of the four present experiments together with the data of Boyer et al [7]. The agreement is good, especially regarding the evolution of the primary shock wave, which is the easiest to track.…”

“…They allow the independent investigation of the influence of the initial energy (through a variation of the initial inner sphere diameter, ∅, case B) and the initial density of the pressurised gas on the mixing process (case C). Case A is the reference one, mimicking the conditions of the study of Boyer [7] for crossvalidation.…”

“…Thus, a jet of air was Table 4 Corrected pressure and scaling coefficients Test Fig. 14 Comparison of experimental wave diagrams with data from Boyer [7]. From left to right on each data set: secondary shock wave, interface external radius and primary shock wave pushing upwards along the centre of symmetry of the flow, which explains why the secondary shock wave reflections do not occur at the origin.…”

“…This study relies on both numerical work and experimental work. The set-up, which is essentially a spherical shock tube similar to the one used by Boyer [7] in 1959, consists of bursting air-pressurised glass spheres. Even though it does not involve the detonation of a HE, it produces a similar flow, which is representative of the one following a spherical detonation [8].…”

Exhaust of Underexpanded Jets from Finite Reservoirs

“…The exhausting jet structure is consequently affected by the changing reservoir-to-ambient-pressure ratio. In a spherical blast where the back pressure continually decreases, for example, experiments [8] and analysis [9] show the secondary shock initially propagates outward but then recedes back toward the origin. In a numerical study of open-ended shock tubes, Haselbacher et al [10] found that, if the pressure ratio was sufficiently large, the expansion fan accelerated the flow to supersonic conditions, and the exhausting expansion fan head affected the underexpanded jet structure.…”