A simple electrometric method for parametric determination of Jones-Wilkins-Lee equation of state from underwater explosion test

Abstract

The parametric determination of the Jones-Wilkins-Lee equation of state (JWL-EOS) of condensed explosives was mostly dependent on a cylinder test using a high-speed photography technique. In the present work, a simple electrometric method based on the underwater explosion test was developed with a novel pressure-conducted velocity probe permitting recording the detonation and shock wave velocity in a single test. Specifically, a velocity probe-based testing setup for the underwater explosion was designed at first to measure the oblique shock wave front of the cylinder charge. We carried out four tests using powdery cyclotrimethylenetrinitramine (RDX) and obtained the curves of detonation-shock front position versus time. The oblique shock wave fronts were then determined based on the analysis of two-dimensional steady flow, and some other parameters such as detonation pressure, adiabatic exponent, Mach number, and gas-water interface angle were calculated combining the Prandtl-Mayer expansion law. Excellent agreements with the calculation results of Kamlet’s semi-empirical formulas were achieved. By applying a numerical calculation and test-and-error process, we adjusted the six JWL-EOS parameters (A, B, C, R1, R2, and ω) constantly to make the error between numerical and experimental results of oblique shock front fall within ±2%. Finally, the JWL-EOS of powdery RDX in each test was determined, and the curves of adiabatic pressure versus relative volume were plotted as well to demonstrate the accuracy of the present method.