چكيده به لاتين
Thermal Protection Systems (TPS) are responsible for protecting those structures which are working in a thermal critical condition. Accurate design and analysis of TPS is very important because if the structures have not been protected correctly, the whole function of the equipments will be stopped. Structures that enter the atmosphere at very high speeds, face hot gases in a nozzle or pass through air at high speeds are examples of those structures that must be protected from aerodynamic and gasdynamic heating. Among various TPS, Ablative TPS (A-TPS) are one of the most successful ones. These materials degrade (ablate) while operating in a critical thermal condition and then reduce considerably the amount of heat transfer across the materials. A successful and reliable design for a thermal protection system requires things such as understanding various physical and chemical phenomena that are involved in the ablation process, having knowledge about A-TPS materials and hyperthermal environments and using advance tools for analysis and assessment.
In this dissertation, modeling of thermal response of an ablative composite that is exposed to a high temperature flow is presented. Large portion of the energy that convect to the material, dissipate through ablation process and transfer away though pyrolysis gas, surface thermochemistry reaction products and surface reradiation. Then the rest of the convected energy, transfer into material. Discretisation of the model is performed by finite-volume method in one dimensional plannar, cylindrical and spherical coordinates. Also for accounting the surface movement, the model uses the variable grid. The numerical method that is presented, avoids the need for energy tridiagonal matrix solution at the each iteration.
The model in implemented in Fortran, also is verified and validated by comparision to results of appropriate references and simulation tools. The solution variables that are used for verification and validation are temperature field, surface recession, pyrolysis and char depth. A parametric study is also performed and effects of variation of the input parameters on solution variables are presented.
