Detonation of A Gaseous CHARGE In A Confined and SEMI-Confined Workshop

Detonation of a gaseous charge in a confined and semi-confined workshop.

Sauvan P.E., Sochet I.¹, Trélat S.², Boulanger R.³, Nozeres F.³, Minard J.P.⁴, Le Naour B.⁴, Munoz D.⁵, Julien B.⁵

¹ Ecole Nationale Supérieure d'Ingénieurs de Bourges – Laboratoire PRISME – UPRES EA 4229 – 88 boulevard Lahitolle, 18020 Bourges Cedex – France ² Institut de Radioprotection et de Sûreté Nucléaire – DSU/SERIC/BEXI – 31 avenue de la Division Leclerc, 92260 Fontenay-aux-Roses– France ³ Nexter Munitions - 7 Route de Guerry, 18023 Bourges Cedex ⁴ MBDA - Rond point Marcel Hanriot, Route d'Issoudun, 18020 Bourges cedex. ⁵ Direction Générale de l'Armement, Techniques Terrestres - Rocade Est, Echangeur de Guerry - 18000 Bourges.

Corresponding author: isabelle.sochet@ensi-bourges.fr

  Abstract

            The detonation of a charge within a pyrotechnic workshop represents a significant hazard to the structure and its employees. The assessment of pressure and impulses produced by shock waves is studied in this paper to investigate how blast propagates through a pyrotechnic workshop and how the propagation is affected by different parameters.

Small scale experiments are conducted with a Plexiglas model of a pyrotechnic workshop and the explosive charge is represented by a homogeneous hemispherical gaseous charge (stoichiometric propane-oxygen mixture). Three positions of the charge are considered: in the centre of the workshop, on the axis and in a corner located at the opposite side of the chimney. Pressure gauges are distributed on the floor and at the centre of each wall. Three main configurations are studied: without a roof, with a roof and without a chimney, with a roof and with a chimney. Pressure-time histories are compared with each other so as to determine the influence of the roof and the chimney on overpressure and impulse levels. Each configuration is tested with and without an obstacle (this obstacle standing for a machine tool) in order to assess its influence on shock waves propagation. The present study highlights that the detonation of an explosive charge in a confined or semi-confined workshop generates Mach stems along walls. This phenomenon significantly increases overpressures and impulses in the vicinity of walls and injuries induced by such a Mach stem are more serious than those caused by the incident shock wave.