Propellants combustion models

Currently, Chemkin only treats chemical reactions for an ideal gas. Efforts are currently underway to extend the Chemkin chemistry to handle the non-idealities of higher pressures. Also, Chemkin does not currently treat the condensed phase. Therefore, for the solid propellant combustion model treated in this paper, a single-step condensed phase reaction mechanism was hard-wired into the computer code. 

With these goals in mind, several investigators have undertaken to set down quantitative expressions which will predict propellant burning rates in terms of the chemical and physical properties of the individual propellant constituents and the characteristics of the ingredient interactions. As in the case of ignition, the basic approach taken in these studies must consider the different types of propellants currently in use and must make allowances for their differences. In the initial combustion studies, the effort was primarily concerned with the development of combustion models for double-base propellants. With the advent of the heterogeneous composite propellants, these studies were redirected to the consideration of the additional mixing effects. 

Beckstead, M. W, Model for Double-Base Propellant Combustion, AlAA Journal, Vol. 18, No. 8, 1980, pp. 980-985. 

Hermance, C. E., A Model of Composite Propellant Combustion Including Surface Heterogeneity and Heat Generation, AIAA Journal, Vol. 4, No. 9,1965,... 

Niioka, T, and Mitani, T, An Analytical Model of Solid Propellant Combustion in an Acceleration Field, Combustion and... 

In summary, all features of the liquid rocket engine combustion processes are extensively affected by injector design, and any simplified combustion model, in which the essential three-dimensional nature of the flow processes is ignored, can only be of qualitative significance. Nevertheless, these simplified models are useful in giving us some insight into the nature of the physicochemical phenomena that determine engine performance. In this connection, steady-state combustion rates and overall combustion efficiencies in propellant utilization are far less important practical problems than are control or elimination of instabilities, excessive heat transfer, and hard starts. 

A. Analytical Models of Propellant Combustion and Detonation 57) N.S. Cohen C.F. Price, Combustion of Nitramine Propellants , JSpacecraft -Rockets 12 (10), 608-12 (1975) CA 84,... 

The earliest simplified models of composite propellant combustion were models in which pyrolysis laws like equation (6) were applied separately to the fuel (F) and oxidizer (O) constituents [8], [28], [66]. Since the parameters A and E in expressions like m = differ for fuel and oxidizer,... 

For heterogeneous propellants, the current situation is much less satisfactory. The complexity of the combustion process was discussed in Section 7.7. To employ a result like equation (66) directly is questionable, although attempts have been made to evaluate parameters like A and B of equations (67) and (68) from complicated combustion models for use in response-function calculations [81], [82]. Relatively few theories have been addressed specifically to the acoustic response of heterogeneous propellants [82]. Applications of time-lag concepts to account for various aspects of heterogeneity have been made [60], [83], a simplified model—including transient variations in stoichiometry—has been developed [84], and the sideways sandwich model, described in Section 7,7, has been explored for calculating the acoustic response [85], There are reviews of the early studies [7] and of more recent work [82],... 

F. J. Higuera and A. Linan, Stability of Solid-Propellant Combustion to Non-Planar Perturbations in Dynamics of Flames and Reactive Systems, vol. 95 of Progress in Astronautics and Aeronautics, J. R. Bowen, N. Man son, A. K. Oppenheim and R. I. Soloukhin, eds.. New York American Institute of Aeronautics and Astronautics, 1984, 248-258, have shown that a similar phenomenon occurs for the model that led to equation (78). When transverse disturbances are admitted, the stability boundary in Figure 9.6 is changed to f... 

The nitrogen chemistry associated with combustion in air is not dealt with in the set of papers by Tsang just cited, but in two similar publications on the high-temperature data for modelling propellant combustion, data on some of the relevant nitrogen reactions are evaluated. The reactions covered are those of the species NO, NO2, HNO, HNO2, HCN, N2O [59] and CN, NCO, HNCO [60]. 

Figure 6 shows schematically the physiochemical processes involved in the HMX/GAP pseudo-propellant combustion. A physical model for RDX/GAP pseudo-propellant combustion is available in Ref. 38. The entire combustion-wave structure is segmented into three regions solid phase, near-surface... 

---