학술논문
不同氢气喷孔直径对汽油掺氢X型转子发动机性能及污染物排放的影响 / Impact of Different Hydrogen Nozzle Diameters on Performance and Pollutant Emission of X-Type Rotary Engine
Document Type
Academic Journal
Author
Source
西安交通大学学报 / Journal of Xi'an Jiaotong University. 58(2):66-78
Subject
Language
Chinese
ISSN
0253-987X
Abstract
针对高效X型转子发动机汽油燃烧不充分的问题,提出了一种缸内直喷掺氢方法用于提升燃烧效率和发动机热力性能.建立了 X型转子发动机三维CFD数值模型,通过缸压、放热率和功率实验数据验证了模型有效性,在喷氢总量、喷氢压力、喷氢开始时刻相同的条件下,分析了氢气缸内直喷且汽油预混时氢气喷孔直径对发动机缸内流动、燃烧、热力性能以及污染物排放特性的影响,并与纯汽油预混式发动机性能进行对比,揭示了缸内直喷掺氢方法的优越性.结果表明,在小氢气喷孔直径(2mm)下,火焰传播比较均匀,且在燃烧室两侧狭缝中都有较大的对称的火焰,燃烧更加充分,发动机指示热效率达到了最高37.07％,较不喷氢和大氢气喷孔直径(4mm)分别提高了10.23％和7.85％.与大氢气喷孔直径相比,虽然小氢气喷孔直径下NOx排放量上升了 21.12％,但是碳氢化合物、碳烟排放量分别下降了 79.08％和2.17％.小氢气喷孔直径(2 mm)为最优喷氢方案,研究为X型转子发动机的喷氢方案设计与优化提供了指导.
Aiming at the issue that the combustion of gasoline in high-efficiency X-type rotary engine is insufficient,a method of cylinder hydrogen direct injection is proposed to improve the combustion efficiency and thermodynamic performance of the engine.The three-dimensional CFD numerical model of X-type rotary engine is established and validated via the experimental data of cylinder pressure,heat release rate and power.Under the same hydrogen injection total mass,pressure,and start time,the impact of hydrogen injection nozzle diameter on the in-cylinder flow,combustion,thermodynamic performance and pollutant emission of the engine when hydro-gen in-cylinder direct injection and premixed gasoline are adopted.The advantages of hydrogen in-cylinder direct injection method are revealed by comparing with pure gasoline premixed engine.The results show that when the hydrogen injection nozzle diameter is small(2 mm),the flame propagation is more uniform,and relatively large symmetrical flames are found in the slits of both sides of combustion chamber,making the combustion more sufficient.The maximum indicated thermal efficiency of corresponding engine reaches of 37.07％,which is 10.23％and 7.85％higher than that of the engine without hydrogen injection and with a large hydrogen injection noz-zle diameter(4 mm),respectively.In addition,compared with the large hydrogen injection nozzle diameter,although the NOx emissions increase by 21.12％when the hydrogen injection nozzle with small diameter is adopted,the HC and soot emissions decrease by 79.08％and 2.17％,re-spectively.Thus,the small hydrogen injection nozzle diameter(2 mm)is the optimal hydrogen injection strategy.This study provides guidelines for the design and optimization of the hydrogen injection strategy of X-type rotary engine.
Aiming at the issue that the combustion of gasoline in high-efficiency X-type rotary engine is insufficient,a method of cylinder hydrogen direct injection is proposed to improve the combustion efficiency and thermodynamic performance of the engine.The three-dimensional CFD numerical model of X-type rotary engine is established and validated via the experimental data of cylinder pressure,heat release rate and power.Under the same hydrogen injection total mass,pressure,and start time,the impact of hydrogen injection nozzle diameter on the in-cylinder flow,combustion,thermodynamic performance and pollutant emission of the engine when hydro-gen in-cylinder direct injection and premixed gasoline are adopted.The advantages of hydrogen in-cylinder direct injection method are revealed by comparing with pure gasoline premixed engine.The results show that when the hydrogen injection nozzle diameter is small(2 mm),the flame propagation is more uniform,and relatively large symmetrical flames are found in the slits of both sides of combustion chamber,making the combustion more sufficient.The maximum indicated thermal efficiency of corresponding engine reaches of 37.07％,which is 10.23％and 7.85％higher than that of the engine without hydrogen injection and with a large hydrogen injection noz-zle diameter(4 mm),respectively.In addition,compared with the large hydrogen injection nozzle diameter,although the NOx emissions increase by 21.12％when the hydrogen injection nozzle with small diameter is adopted,the HC and soot emissions decrease by 79.08％and 2.17％,re-spectively.Thus,the small hydrogen injection nozzle diameter(2 mm)is the optimal hydrogen injection strategy.This study provides guidelines for the design and optimization of the hydrogen injection strategy of X-type rotary engine.