Detonation transformations in an aerated liquid

Abstract

In this work the DEGDN was obtained by the standard method [4] from diethylene glycol (pure grade) and gelled with a small quantity (3%) of KNh colloxylin (12% N). The nitromethane (PNR production) was used without additional purification: special experiments established that the critical diameter of detonation of the mixture of purified nitromethane with colloxylin (3%) is the same as that of the unpurified compound (13  0.5 mm). The degree of aeration was characterized by the "porosity" m = 1 -- ~, ~ = 0o/0, where 0o and p are the densities of the sample and homogeneous liquid. Aeration of the gelled DEGDN up to a porosity of ~0.5 was carried out by foaming it with an addition of a small quantity of OP-7 surfactant with amechanical mixer in two variants: i) with a constant number of rotations of the mixer (45 rps) and a surfactant content of -1% the starting porosity was fixed by the mixing time; 2) for constant mixing time (30 min) and a somewhat lower rate of rotation of the mixer (25-30 rps) ~he required density was obtained by varying the surfactant con=ent (from 0.04 to i.1%). In =he case of nitromethane (for which a surfactant could not be chosen) the density after gelling was varied hy introducing microspheres consisting of phenol formaldehyde resin (liquid density of 0.243 g/cm 3) 0.04 mmindiameter; conglomerates of microspheres up to 0.2 ran in size were also present. To obtain DEGDN porosity of less than 0.5 it was mixed with porous phenol formaldehyde resin with mipora. With a mipora content of 30% it was possible to obtain a mixture whose density equalled only 0.13 g/cm s (m = 0.91). Experiments on the determination of the critical diameter and detonation velocity were performed in glass tubes with walls 1 mm thick, and a charge length of up to 20 cm (in all cases not less than ten diameters of the charge). The detonation velocity was determined with the help of SFR-2 apparatus. DETONATION VELOCITY The ideal velocity and other detonation characteristics were calculated by the method of [5]. The parameters at the Jouguet point were determined by minimizing the dependence of the detonation velocity D on the pressure p on the detonation adiabat, and the composition of the products were determined by minimizing the Gibbs energy of the products, whose equation of state was determined from the collection of the most reliable shock-wave and detonation measurements. The computational results for homogeneous and porous liquids are presented in Tahie i. The dependence D(po) (Fig. i) is nearly linear. The small break in the case of DEGDN (Fig. la) at po = i g/cm 3 is linked with the formation of condensed carbon in the detonation products. For d = 16-17 mm and in a steel tube the value of D is close to the computed value. As d decreases the difference between the theory and experiment increases. For d ~ 5 mm the detonation velocity increases as p~ increases, passes through a maximum, and then decreases substantially. For Po = 1.2-1.3 g/cm ~ for DEGDN and Po = 0.95-1.05 g/cm ~ for nitromethane the process crosses over to the low-velocity detonation regime (D = 2.0-2.5 km/sec).