摘要
基于纹影法在定容喷射装置上进行了不同喷射压力、环境压力下的氢气射流特性试验,研究外开式喷嘴的氢气射流特性及喷射参数的变化规律。结果表明:氢气射流近场呈现锥形结构,且形成了喷射轨迹线,而射流远场逐渐发展成大尺度球形涡流结构。喷射压力增大,轴向和径向贯穿距离增大而卷吸率减小;背景压力增大,轴向和径向贯穿距离减小而卷吸率增大;射流锥角的变化与喷射压力或背景压力关系不大,但随喷射时间逐渐从80°变小并趋于22°。另外通过归一化分析发现,贯穿距离在不同边界条件下均具有较好的自相似性,自相似系数(x/y)逐渐趋于0.59左右,径向扩散性优于单孔喷嘴氢气射流。合理利用氢气射流特性可以优化直喷氢内燃机的混合气形成,为外开式喷嘴的喷射策略优化提供依据。
Based on the schlieren method,the characteristics of hydrogen jets were tested on a constant volume injection device under different injection pressures and ambient pressures.The hydrogen jet characteristics of outward-opening nozzles and the variation laws of injection parameters were studied.The results show that the near-field of hydrogen jet presents a conical structure and forms a jet trajectory and the far-field of jet gradually develops into a large-scale spherical vortex structure.With the increase of jet pressure,axial and radial penetration distances increase and entrainment rate reduces;while increasing background pressure will show the opposite trend.The jet cone angle gradually decreases from 80°and becomes stable at close to 22°,and willnot be affected by jet pressure or background pressure.According to the normalization analysis,it is found that the penetration distance has a good self-similarity under different boundary conditions and the self-similarity coefficient(x/y)gradually approaches about 0.59.The radial diffusivity is also better than that of single-hole nozzle.Reasonable use of hydrogen jet characteristics can optimize the mixture formation of direct injection hydrogen engine,which provides a basis for the injection strategy optimization of outward-opening nozzle.
作者
张策
孙柏刚
汪熙
包凌志
柴华
ZHANG Ce;SUN Baigang;WANG Xi;BAO Lingzhi;CHAI Hua(School of Mechanical Engineering,Beijing Institude of Technology,Beijing 100081,China;China North Engine Research Institute(Tianjin),Tianjin 300400,China)
出处
《车用发动机》
北大核心
2020年第4期7-12,24,共7页
Vehicle Engine
基金
国家自然科学基金(51276019)。
关键词
氢内燃机
外开式喷嘴
纹影法
射流特性
hydrogen engine
outward-opening nozzle
schlieren method
jet characteristics
