| JP-10 (C10H16) has high energy density, and is one of the preferred fuels being used in scramjets and pulse-detonation engines. It is important to measure the ignition delay time of JP-10 for designing engines and investigating its combustion chemistry. At present, measurements of ignition delay time in shock tubes are few, and the adsorption of JP-10 on the wall in shock tube leads to a large scatter in the measurement results. In present experiments, the adsorption of JP-10 in shock tube was taken into account, and JP-10 concentration was exactly determined. In order to avoid the adsorption of JP-10 in the mixing chamber, JP-10 was injected directly into the shock tube. The shock tube and the mixing chamber were preheated to 70℃and were maintained during the experiment, therefore the adsorption could be reduced. By measuring the gas pressure and using the adsorption curves, JP-10 concentration was conveniently determined, to overcome the difficulty in determining the gas concentrations of heavier hydrocarbon fuels caused by the adsorption on the wall in shock tube experiments. To obtain the ignition time data of JP-10 in the low temperature region, the shock tube was run under the tailored conditions, so that the experiment time of about 7ms could be reached. The whole variations of pressure and emission of the radicalOH orCH were observed in the ignition process by a pressure transducer and a monochromator with a photomultiplier. The present results of experiments show that the two diagnostic ways give no distinctive ignition times by tracing theCH emission through the endwall and theOH emission through the sidewall. Experiments were performed over the pressure range of 1.55.5 atm , temperature range of 10002200 K , fuel concentrations of 0.1%0.55%, and stoichiometries ofφ= 0.25, 0.5, 1.0, 2.0. These measured ignition delay times can be related with the temperature and the concentrations of JP-10 and oxygen. The experimental data demonstrate that there are different dependency relationships for the low and high temperature regions. The transition temperature is about 1400 K . The correlations were obtained by a least square analysis of all the data points in the formτ( s )= 2.12×10-6×[JP-10]-0.34[O2]0.55×exp(80 489/RT) (1000K-11×[JP-10]0.52[O2]-1.2×exp(95 733/RT) (1400K2] in mol / cm3,and E in J / mol.
|
PDF Full Text Request