A Gurney‐type equation was previously corrected for wall thinning and angle of tilt, and now we have added shock wave attenuation in the copper wall and air gap energy loss. Extensive calculations were undertaken to calibrate the two new energy loss mechanisms across all explosives. The corrected Gurney equation is recommended for cylinder use over the original 1943 form. The effect of these corrections is to add more energy to the adiabat values from a relative volume of 2 to 7, with low energy explosives having the largest correction. The data was pushed up to a relative volume of about 15 and the JWL parameter ω was obtained directly. The total detonation energy density was locked to the v=7 adiabat energy density, so that the Cylinder test gives all necessary values needed to make a JWL.
We have performed a series of highly‐instrumented experiments examining corner‐turning of detonation. A TATB booster is inset 15 mm into LX‐17 (92.5% TATB, 7.5% kel‐F) so that the detonation must turn a right angle around an air well. An optical pin located at the edge of the TATB gives the start time of the corner‐turn. The breakout time on the side and back edges is measured with streak cameras. Three high‐resolution X‐ray images were taken on each experiment to examine the details of the detonation. We have concluded that the detonation cannot turn the corner and subsequently fails, but the shock wave continues to propagate in the unreacted explosive, leaving behind a dead zone. The detonation front farther out from the corner slowly turns and eventually reaches the air well edge 180° from its original direction. The dead zone is stable and persists 7.7 μs after the corner‐turn, although it has drifted into the original air well area. Our regular reactive flow computer models sometimes show temporary failure but they recover quickly and are unable to model the dead zones. We present a failure model that cuts off the reaction rate below certain detonation velocities and reproduces the qualitative features of the corner‐turning failure.
We have applied thermal insults on LX-04 at 185 o C and found that the material expanded significantly, resulting in a bulk density reduction of 13%. Subsequent detonation experiments (3 cylinder tests) were conducted on the thermally-damaged LX-04 samples and pristine low-density LX-04 samples and the results showed that the fractions reacted were closed to 1.0. The thermally damaged LX-04 and pristine low-density LX-04 showed detonation velocities of 7.7 to 7.8 mm/µs, significantly lower than that (8.5 mm/µs) of pristine high-density LX-04. Detonation energy densities for the damaged LX-04, low-density pristine LX-04, and hot cylinder shot of LX-04 were 64.8 kJ/cm 3 , 66.2 kJ/cm 3 , and 65.8 kJ/cm 3 , respectively, lower than the detonation energy density of 81.1 kJ/cm 3 for the high density pristine LX-04. The break-out curves for the detonation fronts showed that the damaged LX-04 had longer edge lags than the high density pristine LX-04, indicating that the damaged explosive is less ideal.
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