自由射流出口临界雷诺数的确定

Determination of critical Reynolds number at outlets of free jet flows

将圆形自由射流按重力相似准则设计成6个系列模型,利用PIV测速系统,对射流模型相应不同出口雷诺数的流场、浓度场形态分布特征进行了试验研究,分析了射流流场及涡量场、轴线时均流速、断面流速分布、射流起始段长度等,得出圆形自由射流出口临界雷诺数Rek≥2 000,以及雷诺数Re<2 000时射流起始段长度L0与出口雷诺数Re的关系为L0=kRe-0.57d0.

Six series models for free round jet flows were designed according to the gravity similarity criterion. An experimental study was performed on the forms of flow fields and concentration fields of the jet flow models with different Reynolds numbers at outlets by use of the PIV system, and some factors, such as the flow field, vortex field, timeaverage velocity along the axial direction, flow velocity distribution in cross-sections, and the length of initial sections of jet flows, were analyzed. The conclusion of critical Reynolds number at outlets of free round jet flows Rek≥2000 and the relationship between the length of initial sections of jet flows L0 and Reynolds number at outlets Re, i.e. L0 = kRe^-0.57 d0 for Re 〈 2 000, were finally drawn.