New paradigm for simplified combustion modeling of energetic solids: Branched chain gas reaction
- Univ. of Illinois, Urbana, IL (United States)
- Los Alamos National Lab., NM (United States)
Two combustion models with simple but rational chemistry are compared: the classical high gas activation energy (E{sub g}/RT {much_gt} 1) Denison-Baum-Williams (DBW) model, and a new low gas activation energy (E{sub g}/RT {much_lt} 1) model recently proposed by Ward, Son, and Brewster (WSB). Both models make the same simplifying assumptions of constant properties, Lewis number unity, single-step, second order gas phase reaction, and single-step, zero order, high activation energy condensed phase decomposition. The only difference is in the gas reaction activation energy E{sub g} which is asymptotically large for DBW and vanishingly small for WSB. For realistic parameters the DBW model predicts a nearly constant temperature sensitivity {sigma}{sub p} and a pressure exponent n approaching 1. The WSB model predicts generally observed values of n = 0.7 to 0.9 and {sigma}{sub p}(T{sub o},P) with the generally observed variations with temperature (increasing) and pressure (decreasing). The WSB temperature profile also matches measured profiles better. Comparisons with experimental data are made using HMX as an illustrative example (for which WSB predictions for {sigma}{sub p}(T{sub o},P) are currently more accurate than even complex chemistry models). WSB has also shown good agreement with NC/NG double base propellant and HNF, suggesting that at the simplest level of combustion modeling, a vanishingly small gas activation energy is more realistic than an asymptotically large one. The authors conclude from this that the important (regression rate determining) gas reaction zone near the surface has more the character of chain branching than thermal decomposition.
- Research Organization:
- Los Alamos National Lab., NM (United States)
- Sponsoring Organization:
- USDOE, Washington, DC (United States); Office of Naval Research, Washington, DC (United States)
- DOE Contract Number:
- W-7405-ENG-36
- OSTI ID:
- 541786
- Report Number(s):
- LA-UR--97-2474; AIAA--97-3333; CONF-970727--; ON: DE97008880; CNN: Grant N00014-97-1-0085; Grant N00014-95-1-1339
- Country of Publication:
- United States
- Language:
- English
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