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本文用热线风速仪及数据采集系统对轴对称热卷吸紊流流动近口区的速度和温度分布特性进行了较系统的研究,用烟可视化技术揭示了流动特征。实验发现,在近口区的过渡段中出现波动产生、发展及崩毁现象。测量表明,在z/D约等于5时,流动的径向速度和温度分布呈线性规律,波动崩毁后,流动迅速成为充分发展,此时轴中心处脉动量基本不变,平均量呈高斯分布。实验结黑与chen等人的数值计算结果进行了比较,指出了计算模型的某些缺陷,提出了符合实际情况的修正。
In this paper, we use the hot-wire anemometer and data acquisition system to systematically study the velocity and temperature distribution of the turbulent flow in the vicinity of the axial symmetry, and reveal the flow characteristics with the smoke visualization technology. The experiment found that in the transition zone near the mouth of the area fluctuations occur, the development and collapse phenomenon. The measurement shows that at z / D about 5, the radial velocity and temperature distribution of the flow have a linear law. After the collapse of the wave, the flow rapidly develops fully. At this time, the pulsation in the center of the shaft is basically unchanged and the average is Gaussian distributed. The experimental results are compared with the numerical results of Chen et al., Some defects of the computational model are pointed out, and the corrections to the actual situation are proposed.