Space Conversion Model of Peak Overpressure in Near-Earth Air Blast Shockwave with Cylindrical Charge

The shockwave overpressure is one of the main damage elements of the high energy warhead, and many researchers have paid great attention on it. The spatial propagation boundary of shockwave is determined based on the method of image, division angle and overpressure normalization, and the theoretical calculation method of overpressure in mixed flow field is also established. Firstly, the boundary of shockwave flow field distribution is determined by using the terminal condition of Mach reflection and the geometric constraints formed by connecting three points, including the intersection of triple point trajectory and the horizontal line of height of burst (HOB), the imaginary burst point and real blast center. Secondly, the angle of measuring point (AMP) is equalized and the normalized value equation is constructed based on the piecewise linear assumption of the normalized value of overpressure. Then, the normalized value equation is extended to the functions of the length diameter ratio (k) of cylindrical charge, HOB, equivalent, AMP and scaled distance. Finally, based on the control variable method, the above function is solved by using the calculated results of AUTODYN-2D numerical model of near-earth air blast with cylindrical charge in accordance with the empirical equations and the real explosion results. The results show that the spatial conversion model of peak overpressure with k, scaled HOB, scaled distance and AMP as input parameters can describe the spatial numerical relation of peak overpressure of cylindrical charge in near-earth air blast, and the conversion effect is well.