一种新型旋流燃烧器内甲烷扩散燃烧特性

Methane Diffusion Combustion Performance in a Novel Cyclonic Combustor

采用两步总包反应机理、标准亚网格应力模型与有限速率/涡耗散燃烧模型等对一种新型旋流燃烧器内甲烷-空气扩散燃烧过程进行大涡模拟.凭借旋流离心效应和涡旋效应来控制反应混合和火焰传播特性,实现了一种热流分布均匀、温度波动小的蓝色旋涡状火焰.此外,通过平面激光诱导荧光技术(OH-PLIF)对反应流的OH基分布进行定性测量.研究表明,燃烧核心区与壁面隔离,使得壁面具有自冷却的效应;切向速度沿径向分布呈现中心对称的双峰结构;高速射流经过突扩的喉部强烈吸卷周围的气流,对其起到预热作用,有利于燃料空气的混合和燃烧效率的提高.

A new methane-air diffusion combustion process in a swirl combustor was simulated via a two-step overall package reaction mechanism,using the Lilly sub-grid stress and finite-rate/eddy-dissipation combustion models.Reaction mixing and flame propagation were controlled by the centrifugal and vortex effects of swirling flow.The results showed that a blue swirl flame with uniform heat flow distribution and low temperature fluctuation occurred.Furthermore,the OH distribution of the reaction flow was qualitatively measured using planar laserinduced fluorescence(OH-PLIF).The results suggest that the combustion core area was isolated from the wall,which induces a self-cooling effect in the wall.The radial distribution of tangential velocity presents a centrosymmetric double-peak structure.The methane-air mixture was sucked around the sudden expansion of the throat due to high-speed jet flows,which is beneficial to both the preheating and mixing of fuel-air and the improvement of combustion efficiency.