Thermal and Catalytic Cracking of JP-10 for Pulse Detonation Engine Applications
Creators: name: Cooper, M.
name: Shepherd, J. E.
Publisher: name: California Institute of Technology
Year: 2002

description: Practical air-breathing pulse detonation engines (PDE) will be based on storable liquid hydrocarbon fuels such as JP-10 or Jet A. However, 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-to-detonation transition times associated with low-energy initiators. These effects increase cycle time and reduce time-averaged thrust, resulting in a significant loss of performance. 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 and catalytic cracking have been investigated. 

We have examined the decomposition of JP-10 through thermal and catalytic cracking mechanisms at elevated temperatures using a bench-top reactor system. The system has the capability to vaporize liquid fuel at precise flowrates 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.
description: This work was carried out under P.O. No. 00-592 for Advanced Projects Research, Inc. under AF contract F04611-99-C-0017. Contract administration, mechanical design and fabrication of two components of the facility: the reactor heater and accumulator, were carried out by Advanced Projects Research, Inc. Key participants from APRI included Toby Rossmann, Jay Marsh, Kevin Moore, and Tom Sobota. 

We acknowledge Kathia Devouge for her preliminary design work. Special thanks to Nathan Dalleska, Director of the Environmental Analysis Center at Caltech, for his immensely valuable lessons on the theory and operation of the gas chromatograph. Prof. Mark Davis of Chemical Engineering at Caltech and members of his research group were very helpful with sharing their expertise in zeolite chemistry. In particular, we thank Andrea Wight, Ph.D. student in Chemical Engineering at Caltech, for providing not only many zeolite samples and use of her chemical laboratory but also many helpful discussions on zeolite structure, preparation, and handling procedures. We thank Daniel Lieberman for his contributions to the pre-mixed partial oxidation experiments.