基于随机粒子追踪方法的环形燃烧室点火动态模拟

Simulation of Ignition Dynamics in Annular Combustor Using Stochastic Particle Tracking Method

关键词:  环形燃烧室  随机粒子追踪  点火模型  点火动态  点火试验

Key words:  Annular combustor  Stochastic particle tracking  Ignition model  Ignition dynamics  Ignition experiments

摘要:

为了深入研究低排放燃烧室点火联焰规律，在全新的环形模型燃烧室中开展了点火模拟和试验研究。点火模拟采用随机粒子追踪方法，能够基于时均冷态流场的仿真结果快速模拟火焰传播过程。环形燃烧室包含16个中心分级旋流器，仅向预燃级通入丙烷，用于模拟航空发动机低排放燃烧室点火状态下的空气燃油分级。试验采用PIV技术测量3个头部区域流场，利用高速相机拍摄火焰CH*/C2*基团化学发光信号。对多个流量和当量比条件下的联焰过程、联焰时间和传焰速率进行了分析，试验和模拟的结果均表明：环形燃烧室内火焰双向传播，燃烧室内外环流速度差异导致了双向火焰传播速度差，传焰速率随燃烧室湍流速度和当量比的增加而增加。点火模型很好地捕捉了环形燃烧室点火动态，所得传焰速率也符合湍流火焰传播规律，表明该模型具有较强预测能力。

Abstract:

In order to deeply understand the ignition dynamics of low-emission combustors， numerical and experimental investigations were carried out in a novel annular combustor. The ignition model is implemented with stochastic particle tracking method and is able to efficiently simulate the flame propagation process based on time-averaged cold flow fields. The annular combustor is composed of 16 centrally-staged swirlers and propane is introduced to the pilot stage only， which mimics the air-fuel split of low-emission combustors at ignition condition. Velocity distributions downstream of three domes were measured by the PIV technique， and flame CH*/C2* chemiluminescence were recorded by a high speed camera. For several conditions with varying air mass flow rate and equivalence ratio， ignition simulations and experiments were carried out and were used to analyse the flame movement， time and speed of the light-round. The simulation and experiments both revealed that there were two flame branches propagating in opposite directions at different speeds induced by the global circular flow motion in the annular chamber. It was also found that the light-round speed increased with turbulent velocity and equivalence ratio. The proposed ignition model captured well the light-round dynamics and the simulated light-round speed also agreed with turbulent flame speed theory， which suggests that the model has promising predictive capability.