基于LPP的多点喷射低污染燃烧室头部方案优化研究

Optimized Study of a Dome for Low Emission Combustor with Multipoint Injection Based on LPP

为了研究贫油预混预蒸发（LPP）燃烧室的性能,设计了两个方案的单管燃烧室。两个方案都采用同心圆式主、副模分区燃烧方式,主模燃油为多点喷射,副模为离心式压力雾化喷嘴。其中方案A主模从外向内喷油,方案B主模从内向外喷油。采用ANSYS CFX软件,对慢车工况和起飞工况的燃烧室进行了数值研究。计算结果表明：流量分配与设计值接近;总压损失介于4%~4.8%;燃烧室有较稳定的回流区和主模出口处大于100m/s的气流轴向速度;工况1时副模富油燃烧,火焰温度高;工况2时主、副模火焰相互独立,主模火焰存在因燃油分布不均匀而产生的高温点;两个方案的出口热点指标均小于0.26;燃烧效率大于99%;污染物排放水平与国际先进水平相近。两个方案在各方面性能上基本接近,方案A略微优于B。

Two different kinds of tubular combustors were designed in order to obtain the performance of lean premixed pre-vaporized（LPP）combustor. Staged combustion was achieved in both cases by co-axial main and pilot module. Multipoint injection was adopted in main module while pressure swirl atomizer was adopted in pilot module. Main fuel was injected from outer wall in case A while main fuel was injected from inner wall in case B. Numerical investigation was conducted by ANSYS CFX from takeoff condition and idle condition. Results show that distribution of mass flow rate was closed to designed values and total pressure loss was between 4% and4.8%. Stable recirculation zone was found and axial velocity was over 100m/s at the outlet of main module. Pilot fuel was rich burned with high flame temperature,when combustors were operated under condition 1. Hot spot caused by non-uniform fuel distribution were found in main flame under condition 2 while main and pilot flame were separated. Pattern factor was less than 0.26 in both cases and combustion efficiency were above 99%. Pollutant emission was closed to international advanced level. From results,two cases were closed from every aspect of performance,and case A was a little better than case B.