An experimental study on DDT distance of JP-8 mixtures

Previous research into detonation physics has mostly utilized gaseous fuels such as hydrogen, acetylene, ethylene, and propane. If these fuels were to be used for a pulse detonation engine, they have to be stored under high pressure in steel containers which increase weight safety risks. In order to increase energy density of fuel, liquid fuel was chosen. Tests were conducted on detonation initiation of JP-8/oxygen mixtures at different initial temperatures and equivalence ratios. These tests found a reduction in the rich limit with increasing initial temperature, and the minimum deflagration-to-detonation run-up distance was approximately 200 mm, which was similar to propane/oxygen mixture results. A rapid increase in deflagration-to-detonation run-up distance was observed at equivalence ratios close to the lean and rich limits. Experiments of JP-8/oxygen and propane/oxygen mixtures with nitrogen dilution were also conducted. As the nitrogen/oxygen ratio increased, the lean and rich limits decreased while the detonation wave could not be successfully initiated as the nitrogen-to-oxygen ratio was greater than 0.4.