NUMERICAL AND EXPERIMENTAL STUDY OF WAVE SHAPER EFFECTS ON DETONATION WAVE FRONT

Abstract

Objective of the current study is to observe detonation wave front by streak camera at the interface of liner and explosive during the course of high explosive detonation in two experiments one without wave shaper and other with wave shaper. Streaks were studied for concentricity between the casing, high explosive and the liner. Although the liner is replaced with the perspex mask, results will clearly reflect the concentricity of explosive and liner. Streaks were also studied for the porosity and cracks in the high explosive. To observe these effects circular grooves were machined on the perspex mask at predefined locations. Grooves machined on the perspex mask were circular but the recorded streaks were elliptical in shapes. This happened because of the viewing angle of the camera. It was observed from the width of the streaks along the periphery of the circles that there was no porosity in the high explosive. Circular streaks also revealed that the assembly was perfectly coaxial along the whole length of the casing during the detonation of high explosive. On the basis of streaks obtained by rotating mirror camera (RMC) shock front arrival velocities were calculated; deviation between the shock front arrival velocities taken at specified location on the surface of the liner in experiment without wave shaper is ± 0.554. Same data taken from the simulation gave a standard deviation of ± 0.464. Similarly the standard deviation between the shock front arrival velocities taken at specified location on the surface of the liner in experiment with wave shaper is ±0.489 and when the data from simulation was analysed it gave a deviation of ±0.367. Standard deviation among velocities obtained from experiment with wave shaper has less variation as compared to experiment without wave shaper both in experiment and simulation. It was observed that the shock front velocity increased by 20.87 % when wave shaper was incorporated. Increased shock front velocity is an indication of the top attack. This velocity increase is much higher near the apex of the cone, which is in agreement with the simulation. Apex is the region which contributes to the jet formation; as a result of this top attack the jet length vis a vis penetration increases which can be verified by penetration experiments.