Burning rate temperature sensitivity

Atwood, A. I., Boggs, T. L, Curran, P. O., Parr, T. P., and Hanson-Parr, D. M., Burn Rate of Solid Propellant Ingredients, Part 1 Pressure and Initial Temperature Effects, and Part 2 Determination of Burning Rate Temperature Sensitivity, Journal of Propulsion and Power, Vol. 15, No. 5, 1999, pp. 740-752. 

The burning-rate temperature-sensitivity parameter k) is shown in Fig. 7. The usual dimensional temperature sensitivity Op = k/(7 Tg) can be obtained by... 

Fig. 19 Burning rate temperature sensitivity for HMX. Experimental data from Boggs, et al. [29] Boggs [31] Parr, et al. [30].

R. C. Strittmater, E. M. Wineholt, and M. E. Holmes, The Sensitivity of Double Base Propellant Burning Rate to Initial Temperature, MR-2593, BRL, Aberdeen, Md., 1976. 

In this equation, Summerfield has shown that the parameter b1 should be very sensitive to the flame temperature of the propellant. At the same time, the factor b2 should be strongly dependent on oxidizer particle size. To check these predictions, Summerfield prepared four propellants using 120 and 16 oxidizer particles at 75 and 80% loadings. Correlation of the burning-rate data with Eq. (39) yields the values for the parameters given in Table I. The experimentally observed trends are consistent with predicted effects. 

In general, the burning rate of an energetic material is seen to increase linearly with increasing pressure in an hr p versus hr rplot represented by Eq. (3.68) at constant initial temperature Tq. Thus, the pressure sensitivity of burning rate at a constant initial temperature, n, is defined by... 

The temperature sensitivity of the burning rate defined in Eq. (3.72) is a parameter of considerable relevance in energetic materials. 

The burning rate of GAP copolymer increases linearly with increasing pressure in an In rversus Inp plot, as shown in Fig. 5.17. The pressure exponent of burning rateat a constant initial temperature, as defined in Eq. (3.71), is 0.44. The temperature sensitivity of burning rate at constant pressure, as defined in Eq. (3.73), is 0.010 K"h... 

Fig. 6.16 Burning rates and temperature sensitivities of high- and low-energy doublebase propellants.

The temperature sensitivity of burning rate thus comprises 60 % high-energy propellant is due to the lower activation energy and the higher temperature in the fizz zone as compared to the low-energy propellant. 

Though both propellants contain equal amounts of NC and NG, the burning rate of NC-NG-GAP is approximately 70% higher than that of NC-NG-DEP at Tq = 293 K. The pressure exponent of burning rate remains relatively unchanged at = 0.7 by the replacement of DEP with GAP. However, the temperature sensitivity of burning rate defined in Eq. (3.73) is increased significantly from 0.0038 K" to 0.0083 K- ... 

Fig. 6.19 Burning rates of a nitro-azide (NC-NG-GAP) propellant at different initial propellant temperatures, showing high temperature sensitivity.

Fig. 7.19 shows the burning rates of AP-HTPB composite propellants at 243 K and 343 K. The propellants are composed of bimodal fine or coarse AP particles. The chemical composihons of the propellants are shown in Table 7.2. The burning rates of both propellants are seen to increase linearly in an In r versus In p plot in the pressure range 1.5-5 MPa, and also increase with increasing initial propellant temperature at constant pressure.Ii l The burning rate increases and the temperature sensitivity decreases with decreasing AP particle size. 

Fig. 7.20 shows the effect of an added catalyst on the burning rates of propellants composed of fine or coarse AP particles. The added catalyst is 2,2-bis(ethylferro-cenyl)propane (BEEP). The burning rates of both propellants are seen to be increased significantly by the addition of 1.0% BEFP. BEFP has a more pronounced effect on the burning rate of the propellant composed of fine AP particles than on that of the propellant composed of coarse AP particles. The temperature sensitivity of the propellant composed of fine AP particles with 1.0% BEFP is lower than that of the propellant composed of coarse AP particles with 1.0% BEFP. 

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