2020级硕士生黄可欣撰写的关于加装叶轮T型通道中热混合特性的文章被国际权威期刊Applied Thermal Engineering 杂志录用。

论文题目：Numerical simulation of the mixing behaviour of hot and cold fluids in the rectangular T-junction with/without an impeller

论文作者：Kexin Huang, Bo Su, Tong Li, Hanbing Ke, Mei Lin, Qiuwang Wang

DOI：10.1016/j.applthermaleng.2021.117942

摘要：

    Thermal stratification is the main reason for thermal fatigue failure in the rectangular Tjunction. An impeller is set in the mixing zone in the rectangular T-junction to improve the mixing behaviour of hot and cold fluids under the deflecting jet with the inflow momentum ratio of MR = 0.49. Blade numbers and blade diameters are investigated for the range of Np = 2 ∼ 4 and Dp* = 0.33 ∼ 0.8, respectively. By the application of large-eddy simulation, the flow fields and temperature fields are obtained in this work. The flow fields show the mixing behaviour between hot and cold fluids can be promoted by setting the impeller with a constant rotation speed, and three flow patterns including the wall jet,
deflecting jet and impinging jet will be observed in the T-junction, which is effective for breaking the thermal stratification. Temperature fluctuation and temperature gradient calculated by mean temperature are compared with that of no impeller. It is found that by adding the impeller the temperature gradient is reduced while the temperature fluctuations almost keep the same. The criterion of mixing length is proposed according to the mass mean temperature and the mixing lengths for different conditions are obtained, as well as the temperature uniformity parameter is proposed to evaluate the mixing degree in the T-junction. The results indicate that the relationship between the mixing length and blade diameter is not monotonic and the optimal operating point is around Dp* = 0.5 for the impeller of 2 blades. By combining the temperature fields and pressure drops, the results indicate among Np = 2 ∼ 4, the impeller of 3 blades is the best choice. Temperature
power spectrum is also investigated and it is possible to control the critical frequency of temperature fluctuation in the duct by changing the blade numbers.