Cylinder Expansion (CYLEX) Test Simulations

The Cylinder Expansion Test (CYLEX) measures the velocity of a copper cylinder which contains a detonated explosive. Variations in the CYLEX test method include: cylinder (tube) length/diameter (l/d) ratio, supporting methods for the tube ends, explosive booster strength, and placement locations for the photonic Doppler velocimetry (PDV) probes. CTH hydrocode simulations were performed to determine the effect of tube (l/d) ratio on wall velocity histories at differing probe locations, effect of booster strength, effect of fixed versus free supporting methods, and estimation of pressure-temperature states in the detonation product gas near the PDV measurement point. Simulation results showed the following. First, a (l/d) ratio of 12 was sufficient to allow the velocity histories to be measured by multiple PDV probes. Second, booster strength did not affect velocity histories for Composition B explosive. Third, the tube confinement method did not affect the velocity histories. Finally, the time period at which the detonation product gas was at a high temperature or pressure was small compared to the time required for the products to reach a relative volume expansion of 7. This expansion corresponds to a one-inch CYLEX expansion of ≈19-mm.