Analysis of the flame–wall interaction in premixed turbulent combustion

Abstract

The present work focuses on the flame–wall interaction (FWI) based on direct numerical simulations (DNS) of a head-on premixed flame quenching configuration at the statistically stationary state. The effects of FWI on the turbulent flame temperature, wall heat flux, flame dynamics and flow structures were investigated. In turbulent head-on quenching, particularly for high turbulence intensity, the distorted flames generally consist of the head-on flame part and the entrained flame part. The flame properties are jointly influenced by turbulence, heat generation from chemical reactions and heat loss to the cold wall boundary. For the present FWI configuration, as the wall is approached, the ‘influence zone’ can be identified as the region within which the flame temperature, scalar gradient and flame dilatation start to decrease, whereas the wall heat flux tends to increase. As the distance to the wall drops below the flame-quenching distance, approximately where the wall heat flux reaches its maximum value, chemical reactions become negligibly weak inside the ‘quenching zone’. A simplified counter-flow model is also proposed. With the reasonably proposed relation between the flame speed and the flame temperature, the model solutions match well with the DNS results, both qualitatively and quantitatively. Moreover, near-wall statistics of some important flame properties, including the flame dilatation, reaction progress variable gradient, tangential strain rate and curvature were analysed in detail under different wall boundary conditions.

Scalar Gradient and Strain Rate Statistics in Oblique Premixed Flame–Wall Interaction Within Turbulent Channel Flows

“…More recently, FWI has been investigated in turbulent channel flow using DNS by Gruber et al (2010) in the case of a V-flame, and by Gruber et al (2012Gruber et al ( , 2018, Kitano et al (2015) and Ahmed et al (2019) in the case of turbulent boundary layer flashback. Statistically planar turbulent premixed flames impinging on a flat inert wall at different temperatures have been investigated by Zhao et al (2018aZhao et al ( , b, 2019. These studies have shown that the flame front has a strong influence on the approaching turbulence and at the same time the turbulence significantly affects the flame structure.…”

QFM: quenching flamelet-generated manifold for modelling of flame–wall interactions

“…In that case, quenching occurs only in the near-wall part of the flame. A recently proposed stationary FWI configuration shows advantages in various aspects in understanding FWI [9]. In this type of FWI, the heat loss is directed from the flame zone to the burnt mixture, unlike the situation in the HOQ and SWQ configurations.…”

High-frequency wall heat flux measurement during wall impingement of a diffusion flame

“…Previous studies on premixed flames for spark-ignition (SI) engines show the main features of transient heat flux curves. 6,7,21,22 The heat flux first increases in a fraction of millisecond from zero to a few MW/m 2 and decreases in about the same time. That heat flux spike is attributed to flame wall interaction (FWI) processes: the hot flame front, close to the adiabatic flame temperature, approaches the wall until heat losses cause flame quenching.…”