船用低排放塔式分级燃烧室主燃级喷嘴结构优化研究

Optimization Research on Main Stage Atomizer Structure of Marine Low Emission Tower-Type Coaxial-Staged Combustor

关键词:  船舶燃气轮机  燃烧室  喷嘴  雾化  掺混特性  流场  结构优化

Key words:  Marine gas turbine  Combustor  Injector  Atomization  Mixing characteristics  Flow field  Structure optimization

摘要:

为了满足船舶燃气轮机污染物排放的需求，设计了一种低排放塔式分级燃烧室，并对其主燃级喷嘴进行结构优化，利用数值模拟方法详细研究了不同喷嘴结构下燃烧室的流场特性及性能参数。结果表明，主燃级由直射式喷嘴更换为空气雾化喷嘴时，可有效避免旋流器壁面燃油积碳；燃烧室内油气掺混水平提高，出口温度分布品质改善，出口NO和CO排放量分别降低71.4%和60%。针对空气雾化喷嘴，燃油管道出口与喷嘴出口之间的高度与其内径之比（H/D）对燃烧室油气分布特性和中截面温度分布的影响远高于其空气出口结构形式，H/D过大或过小时，油气掺混水平恶化，污染物排放量增加。燃烧室出口径向温度分布系数随H/D的增大而减小。综合分析燃烧室油气分布、温度分布和性能参数，确定最优喷嘴的H/D=2，空气出口结构为圆柱型。

Abstract:

In order to satisfy the demand of pollutant emissions for marine gas turbine， the low emission tower-type coaxial-staged combustor was designed and its main stage atomizer structure was optimized. The flow field characteristics and performance parameters of combustor were studied under different atomizer structures by numerical simulation. Results show that when plain orifice atomizer is replaced with plain-jet airblast atomizer in main stage， the carbon deposits on the wall of swirler are avoided and fuel-air mixing characteristics are improved. At combustor outlet， the quality of temperature distribution is improved， NO and CO emissions are decreased by 71.4% and 60%， respectively. As for plain-jet airblast atomizer， the ratio of the height between the fuel tube end and atomizer exit orifice to its inner diameter（H/D） has a much higher impact on fuel-air mixing characteristics and temperature distribution in combustor than its air exit geometry. When H/D is too large or too small， the fuel-air mixing level will deteriorate and pollutant emissions will increase. The radial temperature distribution coefficient at combustor outlet decreases with the increase of H/D. Based on the comprehensive analysis of fuel-air mixing characteristics， temperature distribution and performance parameter of combustor， the cylindrical air exit geometry and H/D=2 is determined for optimal atomizer.