Detonation Cell Size Measurements for Gaseous Mixtures of JP-10 and Air

Abstract

*† An experimental study of the detonation properties of the high molecular weight aviation fuel JP-10 was performed. Detonation cell size measurements for mixtures of JP-10 vapor and air at elevated initial temperatures are reported. Experiments are preformed in a 6.2 m long, 10 cm inner-diameter heated detonation tube at an initial mixture pressure of 2 atm and initial temperatures of 373K, 473K and 528K. The first half of the tube is equipped with turbulence producing orifice plates. Flame acceleration leads to detonation initiation within the first 2 m of the orifice plate laden part of the tube and a CJ detonation wave propagates in the smooth second half of the tube. The detonation cellular structure is recorded on a soot foil inserted into the end of the tube. The detonation cellular structure for off-stoichiometric mixtures was found to contain substantial substructure. The average cell size is obtained by measuring the transverse distance between parallel diagonal tracks scoured onto the foil. It was found that to within the measurement uncertainty the cell size changed very little over the temperature range tested. The measured deflagration-to-detonation transition composition limits are found to correlate well with the classical detonation propagation criterion based on the detonation cell size and the orifice plate diameter.