超/亚声速混合层油雾特征

Characteristics of Kerosene Mist in Supersonic/ Subsonic Mixing Layer

关键词:  空间分布  粒径分布  超/亚声速混合层  剪切层  油雾

Key words:  Spatial distribution  Droplet diameter distribution  Supersonic/subsonic mixing layer  Shear layer  Mist

摘要:

为了获得超/亚声速混合层的油雾特征，开展了试验和数值计算研究。借助粒子图像测速系统的脉冲曝光拍摄功能得到混合层内油雾分布及油滴粒径大小，采用商用Fluent软件模拟混合层内油雾运动并获得油滴粒径分布特征。结果表明，沿着流向油雾空间分布包括横向射流区（含横向破碎段与卷吸转向段），和混合层区（含剪切破碎段和跟随运动段）。流向截面油雾分布由近似圆形发展为椭圆形。油雾粒径分布中，Sauter平均粒径（SMD）由初始400μm降低至65μm，横向破碎段和剪切破碎段为SMD减小的主要区域。超/亚声速混合层内较大的速度梯度对燃油液滴的破碎雾化有较强的促进作用，尤其对于大颗粒油滴。

Abstract:

Experimental and numerical investigations were conducted in order to obtain the characteristics of kerosene mist in supersonic/subsonic mixing layer. The spatial distribution and droplet diameter of mist were recorded by pulse exposure photography of particle image velocimetry system while the motion and droplet diameter distribution of mist were obtained by a commercial software Fluent. Results show that the spatial distribution of the mist along streamwise direction is comprised of cross jet region including cross jet breakup stage and entraining diverting stage， and mixing layer region which covers shear breakup stage and droplet tracing stage. The shape of spatial distribution in streamwise cross sections changes from circle to ellipse. The Sauter mean diameter （SMD） of droplets decreases from 400μm to 65μm. The cross-jet breakup stage and shear breakup stage are the two main stages reducing the SMD. The large velocity gradient of the supersonic/subsonic mixing layer is beneficial to the droplet breakup， especially for larger diameter droplets.