Developing better models for laminar and turbulent burning velocities for H2, H2-CH4 and H2-NH3 mixed with air at different Equivalence Ratios.

Abstract

The study of laminar and turbulent burning velocities is critical for understanding combustion behavior and developing efficient and safe combustion systems. This thesis provides an in-depth investigation of the factors that influence burning velocities, particularly for hydrogen mixtures, and the mathematical models used to predict them. We reviewed the historical development of measurement techniques for burning velocities and highlighted the challenges associated with their measurement. Our research revealed that laminar burning velocity is significantly affected by factors such as initial temperature and pressure, equivalence ratio, fuel concentration, and the Lewis number. We explored the impact of these factors on burning velocities and provided mathematical formulations that link burning velocity with the chemical time scale, Lewis number, fuel concentration, and Product temperature. Furthermore, we critically examined various models for predicting burning velocities, including the FLACS mixing rule. Our research underscores the importance of incorporating parameters such as the Lewis number and chemical time scales in predictive models for accurate results. This study contributes to the field of combustion studies by offering an understanding of laminar and turbulent burning velocities, as well as the factors and models that influence them. The insights gained from this research are mainly usable for CFD modelling of explosion hazards. The improved accuracy of the burning velocity models will allow for more accurate predictions of the flame propagation speed and flame stability. This information can be used to optimize the design of combustion systems to improve efficiency and reduce emissions.