5. Sizing nozzle parts

The sizing of phenolic composite nozzle parts must enable us to predict their behavior during use, i.e. from ignition to extinction of the propellant, and even beyond, so as to define their architecture (thickness of ablative and insulating materials, bonding, dimensions of metal parts, clearances, etc.).

The sizing model must therefore be designed on the basis of an in-depth analysis of the phenomena that occur during use.

Consider the material as it is used in the nozzle during firing.

Above a certain temperature depending on the matrix and the heating rate (generally between 300 ˚C and 400 ˚C), the rigidimer decomposes with the production of gaseous species and the formation of a porous residue. This residue consists of the pyrolysis products of the matrix, mainly glassy carbon.

For a...