Database from an analysis of pressure measurements of the blast waves from the explosions of 0.3 g charges of stoichiometric, rich and lean propane/oxygen mixtures

The measurements of blast waves from a series of explosions of stoichiometric, rich and lean propane/oxygen mixtures have been analysed. The explosive mixtures were contained in hemi-spherical soap bubbles, 0.05 m in radius, with total masses in the order of 1 g. The blast waves were measured with a series of piezo-electric transducers, flush mounted in the horizontal surface supporting the charges, at various distances from the centres of the explosions. The measured time-history of hydrostatic overpressure from each transducer was least-squares fitted to the modified Friedlander equation to provide the best estimates of the peak hydrostatic overpressure immediately behind the primary shock, and the positive phase duration. The times-of-arrival (TOA) of the primary shocks at each gauge location were used to determine the shock Mach numbers as functions of distance, and these values were used in a Rankine-Hugoniot relationship to calculate the peak hydrostatic overpressures, also as functions of distance. For all explosive mixtures there was excellent agreement between the direct gauge measurements and the values from the TOA analyses. The results of the analyses of the measurements from the explosions of the three gaseous mixtures have been compared. The results are also compared with those from the ProBlast Excel© Interface (https://doi.org/10.5683/SP2/ZXZQNN). The data from the pressure-gauge measurements are listed in GaugeDatabase.xlsx. The first spreadsheet, TOA, lists the time of arrival of the primary shock at each gauge position for the stoichiometric, rich and lean explosions. These data were least squares fitted to RS = F1(tS) (1), where RS is the radial distance of the shock from the centre of the explosion and tS the time of arrival of the shock. (1) was differentiated with respect to tS to give the shock Mach number, MS = F2(tS) (2). The Rankine-Hugoniot relationship OPS/P0 = F3(MS) (3), was used to determine the peak hydrostatic overpressures, OPS, in terms of the ambient pressure, P0, corresponding with the times of shock arrival, tS and the shock radius, RS. The pressure-time measurements from the stoichiometric, rich and lean explosive mixtures are listed in spreadsheets StoichPt, Rich Pt and Lean Pt, respectively. For each gauge record the measured overpressures relative to the ambient pressure, OP, and the times after the time of shock arrival, t – t0, were least squares fitted to the modified Friedlander equation OP = F4(t – t0) (4), providing fitted coefficients OPS, the peak hydrostatic overpressure immediately behind the shock; α, the exponential coefficient, and t+, the positive phase duration. The fitted coefficients are listed in the spreadsheets. The equations (1), (2), (3) and (4) reference the equations spelled out in GaugeDatabase.xlsx and Gauge Analysis Database.pdf. n the published paper, size restrictions meant that only single examples of the analytical results such as the analysis of shock times of arrival, the least squares fits to the pressure-time measurements, comparisons of the two types of analysis, comparisons of the results from the different explosive mixtures and comparisons of the results with the ProBlast Interface could be given. The results from all the analyses and comparisons are included in Gauge Analysis Database.pdf.