Heat Transfer Modeling of a Charring Material Using Isoconversional Kinetics

ABSTRACT

An isoconversional modeling approach has been considered in the modeling of heat transfer and pyrolysis in a charring material. The isoconversional approach is appealing due to the use of only a single reacting component as opposed to the multi-component model typically used. This reduces the number of required field variables which reduces numerical demands in large multi-dimensional models. In this study, isoconversional parameters have been reduced from available test data for a generic ablative material. The results were evaluated by implementing the approach into a 1-D ablation heat transfer program and modeling the thermal and decomposition response of a charring material subjected to an elevated surface temperature. The results were compared to the same modeling using a traditional multi-component Arrhenius approach. Modeling outputs showed that the two methods produced very similar results when proper care was taken in the tabulated parameters of the isoconversional model which is susceptible to variations in supporting test data and is sensitive to table resolution. The results of this study indicate that the isoconversional model provides a viable alternative to the widely used multi-component approach.

Acknowledgments

This work was sponsored by the Air Force Research Laboratory (AFRL) under the program management of Mr. Lester Knox. The authors would like to thank AFRL and Mr. Knox for their continued support in advancing the state-of-the-art in engineering modeling and simulation.

Additional information

Notes on contributors

Mark E. Ewing

Mark E. Ewing is a Senior Technical Fellow at Orbital ATK Flight Systems. He earned his B.S.M.E. from Utah State University, and his M.S. and Ph.D. in Mechanical Engineering from The Ohio State University. He has 20 years of experience in the solid rocket motor industry, with primary focus on thermal/fluids modeling applications. He has been Principal Investigator on several programs related to the advancement of thermal models and experimental methods, and has led the development of advanced analysis codes used within the industry to model ablation heat transfer and thermochemistry.

Brian Pincock

Brian Pincock completed his undergraduate degree at Utah State University. His research contributions as an undergraduate include participation in alternative fuel development, design of experimental verification systems for fluid dynamic simulations and developing tools for aerodynamic analysis, including computational fluid dynamics. During the course of his undergraduate degree, Brian completed three internships at Alliant Tech Systems, where he was part of the aerothermal analysis and nozzle design teams. Following completion of his studies at Utah State, Brian attended Stanford University, where he obtained a Master degree in Aeronautical engineering. He currently resides in southern California, where he works on the development of experimental and prototype aircraft.