进气氧浓度对转子机燃烧过程的影响研究
Study on the influence of inlet oxygen concentration on the combustion process of the rotaryengine
利用CONVERGE燃烧模拟软件，建立符合富氧汽油转子机燃烧规律的CFD模型，与工况一致下的实验值相比，证明模型可用性。对不同氧气浓度下汽油转子机的燃烧数值进行模拟，分析富氧燃烧状态下转子机缸内火焰传播，燃烧特性和排放的生成过程。当氧气浓度升高时，气缸内火焰温度提升，未燃区面积逐渐缩小，燃烧区域的体积增大，火焰面积向燃烧室后部区域略有扩展；火花塞周边区域的湍动能逐渐升高，火焰传播速度提升；缸内压力峰值有明显提高，其所对应的曲轴转角也相应提前，缸内燃烧情况得到改善；气缸内平均温度最大值显著增大。此外，碳烟、HC排放物生成量浓度明显降低；CO排放物生成量减少，空间分布面积增大；NOx排放物生成量增加。提升氧气的浓度，可在一定程度上提升汽油转子发动机的燃烧和排放特性。氧气浓度为50％时呈现出最优性能。
Based on CONVERGE, a three-dimensional CFD model of a gasoline Wankel rotary engine is built and validated. The combustion process of the rotary engine under different oxygen concentrations was carried out to analyze in-cylinder flame propagation, combustion characteristics and emissions formation. The results showed that with the increment of oxygen concentration, flame temperature increased within the cylinder, unburned area decreased, the volume of the combustion area increased, and the flame area slightly expanded toward the rear area of the combustion chamber. The turbulent kinetic energy in the vicinity of the spark plug was gradually increased, and the flame propagation speed was increased. Meanwhile, the peak pressure in the cylinder was significantly increased, and the crank angle corresponding to the peak pressure was also advanced, thus the combustion in the cylinder was improved. The maximum in-cylinder temperature was increased. In addition, the concentrations of soot and HC emissions were significantly reduced. The mass fraction of CO emissions was reduced, the spatial distribution area was expanded. The amount of NOx emissions was increased. Oxygen-enriched combustion improved the combustion and emissions characteristics of gasoline rotary engines to some extent. Better performance was showed at 50% oxygen concentration.
柴森;史程;
燕山大学 车辆与能源学院,秦皇岛066004;燕山大学 车辆与能源学院,秦皇岛066004;
TK45
Rotary engine Numerical simulation Oxygen enrichment Combustion process CONVERGE
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