Avaliação dos efeitos da atmosfera na ablação dos compósitos carbono-fenólica bobinados

Abstract

A ata da defesa com as respectivas assinaturas dos membros da banca examinadora encontra-se no processo de vida acadêmica do aluno. Dedico este trabalho a minha famíliaminhas filhas Sarah e Sofia, minha esposa Sonia e meus pais Vera Lygia e Ambrosino (in memorian).

A lumped mathematical model for ablation in polymeric composites

“…A second source term came from Equation (20), which represents the heat exchanged by the gases from thermal decomposition with the surroundings. Again, modelling this reaction is beyond the scope of this work.…”

“…Again, modelling this reaction is beyond the scope of this work. However, it is possible to propose a simplified model based on the degradation and oxidation of gases to account their effect on the surface heat flux, as a function of environment pressure, as done by Silva H. [20]. This term represents the chemical reactions on the external surface, considering the reaction with the environmental .…”

“…Arc-jet plasma torches have been widely used for the purpose of characterising ablative materials [11][12][13][14][15][16][17]. In Brazil, several works [18][19][20] study the behaviour of carbon-phenolic materials in arcjet plasma torches and compare the final results with the simulation model described by Machado [21,22]. Figure 1 shows the arc-jet facility of the Aeronautics Institute of Technology (ITA -Brazilian University), where part of the tests described in these works were performed.…”

“…Machado's work [21,22] has been used for simulation of the ablative process in quartz-phenolic and carbon-phenolic composites [18][19][20]. In this model, two regions are represented: virgin material and char.…”

“…However, results obtained by Machado's original model [21,22] presented discrepancies to experimental data [18-20]. The current work proposes a reliable methodology for the physical modelling of the ablation process, considering simplifications of the physical and chemical phenomena through source terms inserted in the energy balance equation (Equation (3)) of Machado's model [21,22].…”