The Critical Energy of Direct Initiation in Liquid Fuel-Air and Liquid Fuel-RDX Powder-Air Mixtures in a Vertical Detonation Tube

Multiphase cloud detonation is an important but complex process, which has not been fully understood yet. Direct experimental data about the critical initiation energy (CIE) and pressure/velocity revolution of high explosive powder-based multiphase cloud detonation is not available in the literature. In this paper, propylene oxide (PO), petroleum ether (PE), isopropyl nitrate (IPN), and a mixture of PE/IPN were individually dispersed to form a cloud in a 200 mm x 5400 mm vertical detonation tube. Subsequently, this cloud was directly ignited by a high explosive. The critical initiation energy of various mist/air mixtures was measured by the up and down method. Meanwhile, the pressure history was recorded by six sensors along the detonation tube. RDX powder was added to the system and sprayed simultaneously with the liquid fuel to form a three-phase gas-liquid-solid explosive cloud. The detonation pressure and velocity of all three-phase cases significantly increased while the corresponding critical initiation energy decreased compared to the liquid-air analogs. The CIE data were found to have a U-shaped curve relationship to the fuel-air ratio in two-and three-phase systems, the minimum is always on the fuel-rich side.