On the formation of Friedlander waves in a compressed-gas-driven shock tube

Abstract

Compressed-gas-driven shock tubes have become popular as a laboratory-scale replacement for field blast tests. The well-known initial structure of the Riemann problem eventually evolves into a shock structure thought to resemble a Friedlander wave, although this remains to be demonstrated theoretically. In this paper, we develop a semianalytical model to predict the key characteristics of pseudo blast waves forming in a shock tube: location where the wave first forms, peak overpressure, decay time and impulse. The approach is based on combining the solutions of the two different types of wave interactions that arise in the shock tube after the family of rarefaction waves in the Riemann solution interacts with the closed end of the tube. The results of the analytical model are verified against numerical simulations obtained with a finite volume method. The model furnishes a rational approach to relate shock tube parameters to desired blast wave characteristics, and thus constitutes a useful tool for the design of shock tubes for blast testing.

Aerodynamic fragmentation of water, ethanol and polyethylene glycol droplets investigated by high-speed in-line digital holography

“…The forward additional peak is attributed to the compression of the air contained in the driven section and to it short length. Such peak disappears for sufficiently longer driven section length as the shock wave pressure profile evolve during its propagation within [33,36,37]. The overpressure stand to 95.5 mbar at a shorter distance d ts = 172 mm.…”

“…Typical shock waves produced by the shock tube and propagating in the near field free atmosphere are fairly well described by the Friedlander function [32][33][34]. The so-called Friedlander function (ideal blast wave) exhibits an overpressure peak with a sharp rising front which decays exponentially then followed by a depression.…”

Dynamics of rapidly depressurized multiphase shock tubes

“…Under this assumption, it is known from the theoretical work of Tasissa et al. (2016) that the exit time of the reflected rarefaction head is which occurs at the location where the subscripts correspond to the regimes in figure 4. Note that is the initial velocity at which the incident rarefaction tail travels.…”

“…This is a reasonable assumption since the particle bed rises at a much slower rate than the local sound speed. Under this assumption, it is known from the theoretical work of Tasissa et al (2016) that the exit time of the reflected rarefaction head is…”

A Shock Tube Used to Study the Dynamic Response of Blast-Loaded Plates

“…A sudden opening of the diaphragms generates a shock wave travelling down the tube and into the low-pressure chamber. By using a relatively small ratio between the lengths of the high-pressure and low-pressure chambers, this experimental setup differs from traditional shock tubes in the way that the reflected rarefaction waves catch up with the shock wave resulting in pressure profiles similar to the blast wave from an explosive detonation [5,6]. The distant flow field is characterized by the occurrence of a normal shock front, i.e., at distances larger than 10× diameter downstream the diaphragms.…”