BLAF: A Blast Field Reconstruction Program from Pressure Histories
ARMY BALLISTIC RESEARCH LAB ABERDEEN PROVING GROUND MD
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The BLAF programs BLAFS, BLAFOP, and BLAFHI are designed to reconstruct parts of a spherical blast field from selected pressure history observations. The reconstruction method is based on a model fitting to the observed flow field and a subsequent numerical integration of the flow governing equations. This manual gives a short outline of the theoretical background, a description of the program and specifications for the input data and their formats. The flow field reconstruction is done in three steps, each step being realized by an independent program, BLAFS for shock fitting, BLAFOP for blast field overpressure fitting and BLAFHI for blast field history calculations. The input for BLAFS consists of observed shock arrival times ts and overpressure ps at a number of distances r. the program determines a shock model function by adjusting all three components of each data point, ts, ps and r. It also accepts incomplete observations where either ts or ps is missing. The output of BLAFS consists of a set of shock model parameters with corresponding error estimates. The BLAFOP program uses as input the results from BLAFS and overpressure history observations at two or more positions. The output is a set of parameters with error estimates of an overpressure field function. The program BLAFHI uses the results of BLAFS and BLAFOP and computes histories of all components of the blast field velocity, pressure, density, and dynamic pressure at distances specified by the user. These computations are done by numerical integration of the flow governing equations.