摘要
以Ｒｅ＝ ５ ６４０ 的水平圆湍射流为对象，用粒子动态分析仪详细测量了单相及两相射流近场（ｘ／Ｄ＜ １５）的轴向和径向时均速度、湍动能及颗粒相浓度的分布。实验选用粒径分布分别为２５±３μｍ 、７０±５ μｍ 和１００±１０ μｍ 等的玻璃微珠（密度ρｐ＝ ２ ５９０ ｋｇ／ｍ ３）代表颗粒相，分析了两相圆湍射流中Ｓｔｏｋｅｓ数变化对射流特性的影响。实验结果表明，Ｓｔ＜ １ 时应考虑颗粒相与气相湍流拟序结构的相互影响，在射流近场的横向截面上，颗粒相轴向速度有超前气相的现象。随着Ｓｔｏｋｅｓ数的增大，颗粒相速度低于气相速度。由于颗粒相的加入，与单相射流相比，两相湍射流中的气相湍动能发生变化。当Ｓｔ＜ １ 和Ｓｔ１ 时，气相湍能都呈增大的趋势，但二者增大的原因不同。
Experimental studies on a round turbulent jet exhausted horizontally have been conducted using a Particle Dynamics Analyzer (PDA).Both single phase jet and particle laden jet conditions are examined.The Reynolds number based on the gas jet exit mean velocity and the nozzle diameter is 5 640.Spherical glass beads with nominal diameters of 25 μm,70 μm and 100 μm are used to represent the particulate phase.Their density is equal to 2 590 kg/m 3.Detailed data of the jet including axial velocity,radial velocity,turbulence energy and the particulate phase flux characteristics have been obtained.Analysis shows that the variance of Stokes number has a significant influence on the jet evolution process.Interactions between the gas phase coherent structures and the particles should be taken into account when St<1.The axial velocity of the particulate phase is larger than that of the gas phase on the given cross section in the proximal field downstream the jet.As the St number increases,such phenomena disappear and the particulate phase velocity lags behind that of the gas phase.The presence of the particles in the jet changes the gas phase turbulence characteristics when compared with the single air jet.The increasing tendency of the gas phase turbulence energy occurs when St<1 and St1.And the different causes for them are explained respectively.
出处
《燃烧科学与技术》
EI
CAS
CSCD
1999年第4期435-440,共6页
Journal of Combustion Science and Technology
基金
国家自然科学基金
清华大学煤的清洁燃烧技术国家重点实验室资助
关键词
圆湍射流
两相流
激光测试技术
Stokes数
Round turbulent jet,Two phase flow,Laser diagnostic technique,Stokes number
