摘要
X型转子发动机由于具有高功重比和高循环热效率的优势,在小型无人机动力领域具有广阔应用前景。为确定X型转子发动机的最优点火时机,构建了X型转子发动机的CFD仿真模型,探究了在不同点火时机下缸内流动特性、燃烧性能以及污染物排放特性,揭示了点火时机对缸内流场、燃料消耗速度、缸压、缸温以及CO、NO_(x)排放的影响规律。结果表明当点火时机由20°CA BTDC提前至35°CA BTDC时,缸内湍流度增加,燃烧速度加快,峰值压力和峰值温度逐步增高,导致了发动机指示热效率上升,且NO_(x)排放明显上升,CO最终排放量相差较小。然而,点火时机的过度提前会使得着火过早,导致发动机热效率下降。因此,存在最佳点火时机35°CA BTDC,使得瞬时放热率峰值达到最高为1.44 J/(°),且热效率达到最高为24.49%。
Being characterized by a large power-to-weight ratio and high thermal efficiency,X-type rotary engine(XRE)is in broad application to small-scale UAVs of the power system.A CFD numerical model of the XRE is constructed to determine the best ignition timing of the XRE.The in-cylinder flow,combustion performance,and pollutant emission characteristics are investigated under different ignition timing.The effects of ignition timing on the in-cylinder flow field,fuel consumption rate,mean pressure,temperature,and CO,NO_(x) emissions are investigated.The results show that as the ignition timing is advanced from 20°CA(Crank Angle)BTDC(Before Top Dead Center)to 35°CA BTDC,the in-cylinder turbulent turbulence increases.Meanwhile,the combustion rate,peak pressure,and peak temperature gradually go up,leading to the increase of the indicated engine thermal efficiency.Besides,there is a significant increase of NO_(x) emission and a slight change of final CO emission with the increase of ignition timing.However,the excessive advancement of ignition timing makes the ignition premature and the indicated engine thermal efficiency descended.An optimal ignition timing being at the 35°CA BTDC,the corresponding peak instantaneous heat release rate and the indicated thermal efficiency reach to the maximums of 1.44 J/(°)24.49% respectively.
作者
耿琪
王学德
杜洋
杨正浩
何光宇
GENG Qi;WANG Xuede;DU Yang;YANG Zhenghao;HE Guangyu(Science and Technology on Plasma Dynamics Laboratory,Air Force Engineering University,Xi’an 710038,China;School of Mechanical Engineering,Xi’an Jiaotong University,Xi’an 710049,China)
出处
《空军工程大学学报》
CSCD
北大核心
2022年第6期17-24,共8页
Journal of Air Force Engineering University
基金
国家自然科学基金(61873351)。
关键词
X型转子发动机
CFD仿真
点火时机
燃烧
热效率
排放
X-type rotary engine
CFD simulation
ignition timing
combustion
thermal efficiency
emissions
