RT info:eu-repo/semantics/doctoralThesis
T1 Characterization of the combustion process of hydrogen/methane/air and ethanol/air mixtures through instabilities generated in expanding spherical flames
A1 Sastre Zamora, Rosaura
A2 Universidad de Valladolid. Escuela de Doctorado
K1 Combustión
K1 Combustion
K1 Combustión
K1 Hydrogen
K1 Hidrógeno
K1 Ethanol
K1 Etanol
K1 33 Ciencias Tecnológicas
AB The study and characterization of the combustion process through the analysis of instabilities generated during flame propagation are fundamental to ensuring the safety and control of such processes. Combustion with excessive instabilities in its flame front can alter its performance, leading to undesired behaviors.This Doctoral Thesis addresses two key aspects. First, a "stability study of the combustion process" is conducted, focusing on analyzing the origin and nature of the intrinsic instabilities in combustion processes of mixtures with different proportions of hydrogen and methane. The experiments, carried out with flame fronts of spherical geometry, were performed in a constant-volume combustion bomb (CVCB), using Schlieren photography to record the process. Secondly, a "stability study of the flame" is developed for ethanol-air mixtures, aimed at analyzing the measurable consequences of the growth of instabilities during the combustion process. These consequences include the acceleration of the combustion process (increase in burning velocity) due to the increase in flame surface area, as well as alterations in the flame front morphology (a phenomenon known as "cellularity"). Both effects are attributable to the growth of instabilities, which can be observed and quantified.To conduct both studies, an initial literature review is presented, addressing the concepts and parameters used in current research on instabilities in spherical flames, as well as their physical explanation and the relationships between them.The methodology for the "stability study of combustion processes" focuses on determining how the fuel ratio influences the origin and development of flame front instabilities. The independent behaviors of the hydrodynamic and thermo-diffusive effects of combustion are also analyzed, as well as their contributions to the growth rate of instabilities, allowing the nature of the combustion process to be identified. Finally, a qualitative analysis of the cellularity phenomenon (when instabilities fully develop in the flame front) is conducted, and parameters that may influence its appearance are identified. On the other hand, for the "stability study of the flame," a model based on the statistical tool "Design of Experiments" (I-Optimal Design) is proposed, designed to predict the onset of cellularity in ethanol flames. The results obtained from this model are compared with previous studies, experimental results, and images obtained using Schlieren photography.
YR 2025
FD 2025
LK https://uvadoc.uva.es/handle/10324/75492
UL https://uvadoc.uva.es/handle/10324/75492
LA eng
NO Escuela de Doctorado
DS UVaDOC
RD 28-abr-2025