Analysis of flame acceleration induced by wall friction in open tubes

TL;DR

This paper investigates how wall friction causes spontaneous flame acceleration in open tubes, combining analytical theory and numerical simulations to understand the dynamics and critical conditions for explosion risk.

Contribution

It develops a theory for the initial exponential flame acceleration in cylindrical tubes and validates it with extensive numerical simulations, advancing understanding of flame dynamics in open channels.

Findings

Flame acceleration occurs when thermal expansion exceeds a critical value.

The initial exponential acceleration stage is characterized and modeled.

Numerical simulations confirm the theoretical predictions.

Abstract

Spontaneous flame acceleration leading to explosion triggering in open tubes/channels due to wall friction was analytically and computationally studied. It was first demonstrated that the acceleration is effected when the thermal expansion across the flame exceeds a critical value depending on the combustion configuration. For the axisymmetric flame propagation in cylindrical tubes with both ends open, a theory of the initial (exponential) stage of flame acceleration in the quasi-isobaric limit was developed and substantiated by extensive numerical simulation of the hydrodynamics and combustion with an Arrhenius reaction. The dynamics of the flame shape, velocity, and acceleration rate, as well as the velocity profile ahead and behind the flame, have been determined.