Abstract: This study employs direct numerical simulation methods to comparatively investigate the flame acceleration and detonation initiation processes in constant-width and variable-width spiral channels. The results indicate that the spiral channel significantly increases the flame surface area through asymmetric stretching along the inner wall, thereby accelerating flame propagation. This stretching effect primarily arises from the non-uniformity of the flow field within the curved channel. Compared to the constant-width spiral channel, the variable-width spiral channel exhibits a higher flame acceleration rate and a reduction in the detonation initiation distance by approximately 36%. This phenomenon can be attributed to two mechanisms: first, based on previous research, increasing the width of the inner channel when the curvature is large significantly enhances the flame acceleration rate; second, the gradual contraction effect of the inner channel increases the velocity gradient between the flame front and rear, thereby strengthening the flame surface stretching effect. This study reveals the influence of geometric characteristics of spiral channels on flame acceleration and detonation initiation performance, providing a theoretical basis for optimizing pipeline design to reduce flame propagation speed and detonation initiation probability.

Key words: spiral channel, flame acceleration, flame propagation, detonation performance, deflagration to detonation transition