Boundary conditions for a moving interface in solving internal ballistics problems (phenomenological approach)

Boundary conditions are examined for two- and three-dimensional calculations of combustion product parameters in ignition channels. These problems are solved to determine the parameters in solid-fuel rocket engines, various types of gas generators, solid-fuel MHD generators, etc., and also in artillery systems, if special calculations are done on the distribution of parameters along powder elements or along channels within powder charges. When analogous boundary conditions must be used in nonigniting channels (for example for a period of gradual ignition), the following problem classes can be designated: pre-ignition, post-burnout, and interignition. It very more important that definite physical and chemical processes, which occur in the combustion layer or on the fuel surface, precede the combustion itself.