Studies on the role of iron oxide and copper chromite in solid propellant combustion

Superadiabatic regimes of combustion of carbon mixed with an inert solid with filtration of the steam-air mixture are studied theoretically and experimentally. The temperature in the combustion wave and the composition of gaseous products are obtained as functions of the fraction of carbon in the fuel and the amount of steam in the gaseous oxidant. In the examined range of the control parameters, the maximum temperature in the combustion wave is shown to depend only slightly on the fraction of carbon in the mixture and the amount of steam in the oxidant gas. Simulations of filtration combustion of carbon with allowance for the kinetics of its oxidation are in good agreement with experimental results. The calculated combustion temperature coincides with that measured in experiments. In calculating the composition of the gaseous products, coincidence with experimental data is observed only for particular compositions with the mass content of carbon under 60%. As the fraction of the fuel exceeds 60%, the yield of CO and H2 increases in experiments, though such a behavior is not predicted by the theoretical analysis. Hypotheses on the reasons for the disagreement in results are put forward and experimentally checked.

Filtration Combustion of a Carbon-Inert Material System in the Regime with Superadiabatic Heating

Gasification of powdered coal in filtration regime with a fuel continuous injection

Results of studies of the combustion of a composite solid propellant based on ammonium perchlorate are presented. The effect of additives of metal oxides is studied for the high and low-temperature decompositions, linear pyrolysis, and combustion of ammonium perchlorate, the decomposition of HClO4, isobutylene oxidation by oxygen and perchloric acid, and the combustion of propellants with various organic combustibles. It is shown that the efficiency of metal oxides in the reactions of oxidation of isobutylene and propellant combustion is related to the energy of the Me—O bond in the surface oxide layer or the enthalpy of formation of this bond. The extremal nature of the catalytic effect of metal oxides on the burning rate of the propellant is due to the small time of residence of the oxide particles in the zone of intense oxidation-reduction reactions. For this reason, the same additives of metal oxides has different effects on the combustion of the propellant with different organic, combustibles, and the most efficient catalyst can be chosen by a simplified algorithm. The potentials for affecting the composite solid propellant via gas-phase oxidation-reduction reactions is indicated by the effect of additives of organic sources of active species—amines and halides.

Catalysis and inhibition of the combustion of ammonium perchlorate based solid propellants

A two-temperature mathematical model of steady filtration combustion of a solid fuel in open systems is proposed. Air or a mixture of air with water vapors is considered as a gaseous oxidizer. The model takes into account that the heat capacities of the phases depend on temperature and composition and that the reactor length is finite and allows obtaining the composition of gaseous combustion products. Calculated results on gasification of a mixture of carbon with an inert component are presented. It is demonstrated that thermodynamic calculations are important for obtaining the upper estimate of gasification efficiency. Even a sufficiently long reactor becomes “short” in the regime of transient combustion waves, which results in more intense entrainment of heat by combustion products and, as a consequence, in lower efficiency of the process.

Model of Vapor—Air Gasification of a Solid Fuel in a Filtration Mode

A two‐temperature mathematical model of steady filtration combustion is proposed. The model takes into account the finite length of the reactor and the dependence of heat capacities of the phases on temperature and composition. The model describes the process of gasification of a solid fuel in a filtration regime. Calculation results for the gasification reaction of a carbon–nert component mixture are presented. The range of fractions of the fuel component is determined in which neither a purely normal nor a purely inverse wave is formed (an approach of a transitional wave is proposed for this interval). It is shown that the combustion temperature is finite within the entire interval of fractions of the fuel component.

Model of Air Gasification of a Solid Fuel in a Filtration Regime

The effects on the burning and thermal decomposition of composite rocket propellants, based on ammonium perchlorate and butyl rubber, of oxide coated catalysts applied to tge surface of the ammonium perchlorate crystals and introduced into the propellant in the form of a colloidal suspension are investigated. It is shown that the possibility of changing the burning rate by means of applying the catalyst on the oxidizer crystal surface is determined by the chemical nature, the content of the compounds deposited on the oxidizer surface, and by the structure of the coating formed on the ammonium perchlorate surface. Excluding the agglomeration of the catalytic additives using the developed methods, the variation in their dispersivity and the nature of localization in the propellant are the indicators of the propellant's performance efficiency within the region of small additive concentrations (up to 0.5%) in the propellant.

Effect of the physical state of the activators on the combustion of composite rocket propellants. I. The applied catalysts

An experimental study is made of a “chemical arc”, a model layered system of solid components, between the end surfaces of which stationary combustion takes place. The rates of combustion of the components in ammonium perchlorate-polyether, ammonium perchlorate-polyethylene, and ammonium perchlorate-butyl rubber systems with catalytic additives (diethyl ferrocene, epoxyethyl ferrocene, and iron oxide) are measured as functions of the distance between the components. A maximum mass combustion velocity is found to exist as a result of the transition from a low velocity (kinetic) to a high velocity reaction regime. The data are in qualitative agreement with theory. The mechanism by which the catalysts affect the combustion characteristics is analyzed.

G. B. Manelis

Papers

Model of Air Gasification of a Solid Fuel in a Filtration Regime

Effect of the physical state of the activators on the combustion of composite rocket propellants. I. The applied catalysts

Effect of catalysts on the combustion of layered systems