Burning Rate Behavior of Catalyzed Liquid Nitrate Esters

1 Burning Rate Behavior of Catalyzed Liquid Nitrate Esters 

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. 

Steinberger and Carderl24.25] measured the burning rates of liquid strands composed of 63 % nitroglycerin and 37 % diethylene glycol. When 5 % lead aspirate was added to the basic liquid strand, they observed an increased burning rate between 4.0 MPa and 13.5 MPa. This effect is qualitatively the same as in the case of a double-base propellant. The burning rate of the liquid strand was increased by 70 % at 6.8 MPa by the addition of the lead aspirate. 

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. 

The results indicate that the reduction of NO to N2 is inhibited by the reduced temperature in the gas phase on the addition of lead tetramethyl. In addition, the same authors examined the effect of alkyl radicals on the flame speed by using different kinds of metal alkyls. They found the flame speed not to be affected by 

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