Research On The Key Technology Of Pneumatic Driven Type Flyer Detonator

Flyer detonator with new flyer excitation device was designed.The combustion performances of excitation powders was measured by closed bomb.The influences of factors on velocity and impact pressure and pulse energy were researched by mathematical model,such as material and diameter and thickness of flyer.The detonation property of detonator with different conditions was tested by lead disc test.A numerical simulation had been made on the process of flyer impact initiation explosives by LS-DYNA software.The main conclusions were as following:(1)The results indicate that combustion velocity of PETN is faster than RDX,but peak pressure lower.The velocity and peak pressure of granulated RDX prepared with different formulations firstly increase and then decrease with increase of KClO4.When the mass fraction of KClO4 is 30%,granulated RDX work best.(2)The main factors influencing the velocity of the flyer are the excitation powders charge conditions(mass and height)and the velocity and the material,diameter and thickness of the flyer。The limiting velocity of the flyer is inversely proportional to the mass of the flyer and proportional to the mass of the excitation powders.The effect of diameter on limiting velocity is greater than the thickness.(3)Increase of diameter and thickness will reduce the impact pressure generated by flyer.Flyers with different materials can produce equal impact pressure under different diameter and thickness。Addition of thickness make a significant increase of pulse time,but diameter has no effects on pulse time.The pulse energy is inversely proportional to diameter and proportional to thickness。(4)When the flyer diameter 2.5 mm and thickness 0.2 mm,flyer of aluminum and titanium can reliable initiated the detonator with medium charge density 1.42 g/cm3 at the height of 3.3 mm acceleration chamber.Detonator were initiated credibly by stainless steel and copper flyer with medium charge density 1.52g/cm3 and 1.49 g/cm3 respectively at the height of 2.8mm acceleration chamber.Diameter has no effects on the height of acceleration chamber.The height of acceleration chamber need decrease with increase of thickness,but the initiation capacity was unchanged basically.(5)With low height or large density,medium charge can cause non-steady detonation.The appropriate density is 0.86-1.49 g/cm3 and the proper height should not lower than 2 mm.(6)A numerical simulation had been made on the process of detonation of button explosive impacted initiation by flyer with LS-DYNA software.The results indicate that the medium charge occur a strong detonation phenomenon and a high pressure is created by the collision of reflection waves for a short time and pressure reduce quickly.Due to the difference of reflection time of spherical detonation wave at the center and edge of shell button,collision occur at different time at the center of output charge.