Experiments Studying Thermal Cracking, Catalytic Cracking, and Pre-Mixed Partial Oxidation of JP-10

Abstract

Practical air-breathing pulse detonation engines (PDE) will be based on storable liquid hydrocarbon fuels such as JP-10 or Jet A. However, without significant advances in initiation technology, such fuels are not optimal for PDE operation due to the high energy input required for direct initiation of a detonation and the long deflagration-todetonation transition times associated with low-energy initiators. In an effort to utilize such conventional liquid fuels and still maintain the performance of the lighter and more sensitive hydrocarbon fuels, various fuel modification schemes such as thermal cracking, catalytic cracking, and partial oxidation have been investigated. We have examined the decomposition of JP-10 through thermal and catalytic cracking mechanisms at elevated temperatures using a benchtop reactor system. The system has the capability to vaporize liquid fuel at precise flow rates while maintaining the flow path at elevated temperatures and pressures for extended periods of time. The catalytic cracking tests were completed utilizing common industrial zeolite catalysts installed in the reactor. A gas chromatograph with a capillary column and flame ionization detector, connected to the reactor output, is used to speciate the reaction products. The conversion rate and product compositions were determined as functions of the fuel metering rate, reactor temperature, system backpressure, and zeolite type. An additional study was carried out to evaluate the feasibility of using pre-mixed rich combustion to partially oxidize JP-10. A mixture of partially oxidized products was initially obtained by rich combustion in JP-10 and air mixtures for equivalence ratios between 1 and 5. Following the first burn, air was added to the products, creating an equivalent stoichiometric mixture. A second burn was then carried out. Pressure histories and schlieren video images were recorded for both burns. The results were analyzed by comparing the peak and final pressures to idealized thermodynamic predictions.