ИСТИНА

The method of numerical simulation of the structure of burnt zone of metallized composite propellants is developed. The method under consideration consists of three stages. On the first stage, a simulation of composite solid propellant structure is performed. An analysis of the propellant structure obtained in calculations is carried out. It is shown that the contacting aluminum particles form lengthy clusters in the propellant volume. The role of the clusters in formation of burnt zone structures is discussed. It is shown that aluminum particles inside the clusters can both sinter in particles heating and merge in particle melting. On the second stage, the thermal conductivity of propellant is calculated. It is shown that there are two types of thermal conductivity of propellant: fast and slow ones. In the fast processes (e.g. combustion) a heat flux goes through the chains of contacted aluminum particles in propellant while a binder and oxidizers do not practically participate in thermal conductivity of propellant. This mechanism of heat exchange take place in propellant combustion and essentially differs from thermal conductivity of propellant under slow change of propellant temperature. Simulation of temperature fields in propellant both in fast and slow processes is carried out. It is shown that temperature field has a corrugated shape in heterogeneous propellant even in steady-state conditions. On the third stage of simulation the thermal, chemical and mechanical evolution of aluminum particles above the propellant burning surface is considered. The adhesive forces between aluminum particles in burnt zone result in formation of coral-like structures above the propellant burning surface. A simulation of the coral-like structures above the burning surface is carried out. A method for modeling of coral-like structures evolution under the action of gasdynamical forces and adhesive forces is suggested. It is well-known that interaction of aluminum particles each other and gaseous products leads to their agglomeration. It is shown that method under consideration allows calculating aluminum agglomeration in composite propellant combustion. Two kinds of agglomeration are considered: fast agglomeration and slow agglomeration. Calculations of aluminum agglomeration under different conditions of combustion were made. The results of calculation are dynamically represented and compared with the well-known experimental data.