Abstract
Boundary layer flame flashback is a phenomenon that may constitute a key challenge for efficient combustion of novel fuels at gas turbine conditions. In the present work, the effect of wall roughness on the laminar boundary layer flashback is studied systematically using numerical simulation. The results indicate that the wall roughness can attenuate flashback speed due to enhanced heat loss in case of low thermal resistance of the wall. The critical velocity gradient of the oncoming flow is shown to decrease with wall roughness level and increase with gas thermal expansion ratio.
Highlights
As global warming and environmental pollution become global issues, clean combustion is receiving special attention in both research and industry
The critical velocity gradient is shown to decrease with wall roughness level and increase with thermal gas expansion ratio
Wall roughness is expected to have a twofold effect on the flashback tendency: On one hand, change of the roughness element height would affect the flow [17]; on the other hand, the heat loss to the wall is going to be modified through the change of the surface area per unit length of the channel
Summary
As global warming and environmental pollution become global issues, clean combustion is receiving special attention in both research and industry. There are relatively few works on the effects of wall roughness on boundary layer flashback. Both nonreacting numerical simulations and flame flashback experiments were used to study the influence of streamwise roughness on flashback [15,16]. Systematic studies of the influence of the wall boundary conditions on nonreacting flow, with focus on both flow characteristics and heat loss, have been conducted over the years. The effect of fine wall roughness on flame flashback has not been studied either numerically or experimentally. The effects of wall roughness and thermal gas expansion on critical velocity gradients and flashback speeds are scrutinized. III, simulation results and their analysis are presented, followed by the Conclusions
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