Mechanics and Modelling of Turbulence–Combustion Interaction

Abstract

Engineering applications of combustion for aviation, automotive and power generation invariably encounter an underlying turbulent flow field. A proper understanding of the complex turbulence–combustion interactions, flame structure and dynamics is indispensable towards the optimal design and systematic evolution of these applications. A predictive solution of turbulent combustion phenomenon in a practical combustion system where all scales of turbulence are fully resolved is extremely difficult with currently available computational facilities. The urgent requirement for the solution of fluid engineering problems has led to the emergence of turbulence models. The turbulence models could be systematically derived based on the Navier–Stokes equations up to a certain point; however, they require closure hypotheses that depend on dimensional arguments and empirical input. Over the past several decades, turbulence models based on Reynolds-averaged Navier–Stokes (RANS) and large eddy simulation (LES) framework have been developed and used for engineering applications. The success of turbulence models for non-reactive flows has encouraged similar approaches for turbulent reactive flows which consequently led to the development of turbulent combustion models. Modelling of the chemical source term remains the central issue of turbulent combustion simulations. In this introductory chapter, we will review the basics of turbulent flows and multiscale interactions between turbulence and combustion, and proceed towards a brief discussion on the state-of-the-art turbulent combustion models.