An acceleration model for low-speed flames in curved channels

Abstract

This study investigates the initial acceleration process of low-speed flames in curved channels. It also examines how the curvature and width of the channels influence flame propagation patterns and mechanisms. Previous research has highlighted the advantages of curved channels in facilitating flame acceleration. Subsequent studies have explored the interaction between pressure waves and flames, particularly in the later stages of flame propagation, leading to a high-speed flame phase. However, the effects of curvature and channel width on the initial acceleration phase of low-speed flames remain unclear. To address this gap, the present study utilizes theoretical methods to analyze the early acceleration phase of flames in curved channels with fixed curvature and width, from the closed end to the open end. Semi-analytical theoretical solutions are derived to determine the shape of the unburned gas flow field, flame front, and flame acceleration rate. The results demonstrate that the flow field shape deviates from axial symmetry to conserve angular momentum, favoring the inner wall of the curved channel and causing the flame front to adhere to it. In channels with small curvature, increasing the width leads to a decrease in the flame acceleration rate. Conversely, in channels with large curvature, widening the channel results in an increased flame acceleration rate. These findings provide theoretical insights for optimizing the design of the front-stage structure of curved detonation channels.