AGGLOMERATION AND BURNING OF ALUMINUM IN SOLID-PROPELLANTS

This work relates to the behavior of aluminum particles included in a solid propellant based on octogene and ammonia perchlorate. During com bustion, these particles cluster near the burning surface and form glo bules that burn in the combustion gases. A correlation law was determi ned relating the initial size of the globule to the burning rate of th e propellant and to its composition (mass fraction and grain size dist ribution). The burning of the aluminum globules was studied, and the e xperimental results show that for pressures between 3 and 5 MPa, the i nstantaneous globule diameter can be correlated with the initial diame ter, the oxidizing gas content, and, to a lesser extent, the test pres sure. The classical droplet combustion law (as a function of the squar e of the diameter) does not satisfactorily account for the results obt ained by this study or those found in the literature. The discrepancy seems to be related to the very high vaporization heat of aluminum.