A GENERALIZED DEPENDENCE OFDETONATION VELOCITY ON CHARGEDIAMETER INCLUDING LOW VELOCITYDETONATION

摘要

According to experimental data available for high explosives, dependence of detonation velocity on charge diameter D(d) comprises two separate branches for low velocity and normal detonations. In an intermediate velocity range steady detonations are not realized. Our consideration shows that this form of D(d) relation stems from the Z–shaped relationship between normal-to-front velocity and front curvature Dn(K), whichhas two turning points. We have got this Z-shaped curve by using a simple model ofsteady nonideal detonation, including the conversion rate equation with a two-termpressure function. Here the first term with the pressure exponent near 1 is responsiblefor the surface burning under conditions typical of low velocity detonation, and thesecond term with the pressure exponent more than 2 controls chemical conversion undernormal detonation pressures. Varying coefficients of this function we have reproducednumerically D(d) relation with two separate branches observed in unconfined charges ofpowdered high explosives. We also demonstrate that the Z–shaped Dn(K) relationshipcould explain some delayed transient effects which have been observed in shockinitiation of explosive materials and, to date, have no clear interpretation.