入口速度比对同轴喷射流三维温度振荡影响的实验研究

实验测量同轴喷射流模型三维温度场和二维速度矢量场，分析不同入口速度比对三维温度振荡的影响。实验结果表明：R<1时，冷热流在底部完成了混合行为，平均温度不呈轴对称分布，而R≥1时，呈轴对称分布，但流体瞬态温度不呈轴对称分布。随着R的增加，冷流随高度增加温度上升的梯度减小，而热流温度下降的梯度则增大；R>1时，流场温度振荡强度小于R≤1的，其强温度振荡发生在冷热流之间和热流与环境流之间的区域。不同R下，温度振荡主要频率均分布在7Hz以内。

Experimental Investigation on Effect of Inlet Velocity Ratios for 3-D Temperature Fluctuation Caused by Coaxial-Jet Flow

An experiment was performed to study the effect of inlet velocity ratios for 3-D temperature fluctuation caused by coaxial-jet flows based on the 3-D temperature and 2-D velocity fields.The experiment results show that the mixing behavior is completed at the bottom of test section in R<1 condition.The averaged temperatures at the bottom of the flow field are asymmetric in R<1 condition,while those are symmetric in R≥1 conditions.The transient temperatures are asymmetric in these cases.With the increment of inlet velocity ratios,the gradients of cold fluid temperatures decrease in height direction,while those of hot fluid temperatures increase.In R>1 condition,the intensities of temperature fluctuations are less than those in R≤1 conditions.The strong temperature fluctuations occur in the regions between the hot and cold flow,as well as between the hot flow and environmental flow in this case.The frequencies of temperature fluctuations are less than 7 Hz.