Nitrate esters combustion

Adams, G. K., The Chemistry of Solid Propellant Combustion Nitrate Esters of... 

Adams, G. K., The Chemistry of Solid Propellant Combustion Nitrate Ester of Double Base Systems, Proceedings of the Fourth Symposium on Naval Structural Mechanics, Purdue University, Lafayette, IN (1965), pp. 117-147. 

Typical materials containing oxygen and nitrogen atoms are nitrate esters, such as nitrocellulose (NC) and nitroglycerin (NG). Nitrate esters contain -O-NO2 chemical bonds in their structures. The oxidizer component is represented by the oxygen atoms and the fuel components are the carbon and hydrogen atoms. The oxidized combustion products are COj and HjO, the AHjp values of which are -8.94 MJ... 

Similar to the situation with nitrate esters, the two-stage gas-phase reaction resulting from the combustion of ADN occurs due to the reduction of NO to N2, which is reported to be a termolecular reaction. The heat flux transferred back from the preparation zone to the melt layer zone dominates the gasification process occurring in the melt layer zone. 

Extensive experimental and theoretical studies have been performed in an effort to determine the decomposition and combustion processes of nitrate esters. This... 

From the discussion in the previous section, it is clear that, above all, NO2, and then NO, are the principal oxidizers produced in the flames of nitrate esters. The reaction of NO2 with aldehydes plays an important role in the combustion of nitrate esters, since these molecules are the major decomposition products of these materials in the first stage of combustion. Pollard and Wyatt studied the combustion process of HCHO/NO2 mixtures at sub-atmospheric pressures.They found that the reaction occurs very rapidly at temperatures above 433 K, the NO2 being reduced almost quantitatively to NO, and the aldehyde being oxidized to CO, COj, and H2O. The order of reaction was found to be one with respect to both reactants. The same result has been reported by McDowell and Thomas.I ] jgg proposed reaction steps are ... 

Fifer, R. L., Chemistry of Nitrate Ester and Nitramine Propellants, Fundamentals of Solid-Propellant Combustion (Eds. Kuo, K. K., and Summerfield, M.), Progress in Astronautics and Aeronautics, Vol. 90, Chapter 4, AIAA, New York, 1984. 

In an attempt to understand the combustion mechanism of catalyzed double-base propellants, several investigators have conducted experiments to measure the burning rates of strands of liquid nitrate esters. The various measurement techniques were very similar to that employed in a conventional solid propellant strand burner. The liquid esters were placed in a tubular container, and the liquid surface regression speeds were measured by optical methods or by the fuse-wire method used in solid-propeUant strand burners. The only important difference between the solid and the liquid strand burning-rate measurements is that the liquid strand burning speed is very much dependent on the diameter of the container. 

It has been shown by many investigators that gas-phase reachons of nitrate esters are affected by the addition of lead compounds. Adams and coworkers studied the gaseous combustion zone of ethyl nitrate.The flame temperature of the ethyl nitrate was found to be reduced by the addition of 0.1-1.0% by mass of lead tetram-ethyl. The results are shown in Table 6.7. 

Steinberger, R., and Carder, K. E., Mechanism of Burning of Nitrate Esters, 5 th Symposium (International) on Combustion, Reinhold, New York, 1955, pp. 205-211. 

The combustion wave structure of RDX composite propellants is homogeneous and the temperature in the solid phase and in the gas phase increases relatively smoothly as compared with AP composite propellants. The temperature increases rapidly on and just above the burning surface (in the dark zone near the burning surface) and so the temperature gradient at the burning surface is high. The temperature in the dark zone increases slowly. However, the temperature increases rapidly once more at the luminous flame front. The combustion wave structure of RDX and HMX composite propellants composed of nitramines and hydrocarbon polymers is thus very similar to that of double-base propellants composed of nitrate esters.[1 1... 

Since NC is a fuel-rich nitrate ester, a nitropolymer propellant with a high NC content generates black smoke as a combustion product. In addition, the combustion of nitropolymer propellants becomes incomplete at low pressures below about 3 MPa and black smoke composed of solid carbon particles is formed. This incomplete combustion is caused by the slow rates of the reactions of NO with aldehydes and CO in the combustion wave. Thus, the nitropolymer propellants are no longer smokeless propellants under low-pressure burning conditions. 

Steinberger, IEC 48, 766—68 (1956) (Flames from nitrate esters a review of recent work) 8) S.S. Penner T.A. Jacobs, "Combustion and Flames", CalTech, Jet Propulsion Center, TechRept No 29(1959) 9) M.G. 

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