Mondal Tanmoy, Hnaien Nidhal, Ajmi Mariem, Ghachem Kouather, Kolsi Lioua
Department of Applied Mechanics, Motilal Nehru National Institute of Technology Allahabad, Prayagraj, Uttar Pradesh 211004, India.
Laboratory of Thermal Processes, Research and Technology Centre of Energy, Hammam Lif 2050, Tunisia.
ACS Omega. 2022 Aug 1;7(32):27864-27875. doi: 10.1021/acsomega.2c00609. eCollection 2022 Aug 16.
A combined turbulent wall jet and offset jet (also known as the dual jet) with and without the presence of a parallel co-flow stream is studied. The standard -ω turbulence model is used to predict the turbulent flow. The study focuses on the effects of the co-flow velocity (CFV) on the heat-transfer characteristics of the dual jet flow with the bottom wall maintained at a constant wall temperature. The CFV is varied up to 40% of the jet inlet velocity, and the height of the offset jet is varied from 5 to 11 times the jet width with the inlet Reynolds number taken as 15,000. The heat-transfer results reveal that the local Nusselt number ( ) along the bottom wall exhibits a peak at the immediate downstream of the nozzle exit, followed by a continuous decay in the rest of the converging region before showing a small rise for a short streamwise distance in the merging region. Further downstream, in the combined region, gradually decreases with the downstream distance. Except the merging region, no influence of co-flow is observed in the other two flow zones (converging and combined regions). In the merging region, for a given offset ratio (OR), remains nearly constant for a certain axial distance, and it decreases as the CFV increases. As a result of the increase in the CFV, the average Nusselt number decreases, indicating a reduction in overall convective heat transfer for higher values of the CFV. A regression analysis among the average Nusselt number (), CFV, and OR results in a correlation function in the form of within the range OR = 5-11 and CFV = 0-40%.
研究了存在和不存在平行共流时的组合湍壁射流和偏置射流（也称为双射流）。采用标准-ω湍流模型来预测湍流流动。该研究聚焦于共流速度（CFV）对底部壁面保持恒定壁温的双射流流动传热特性的影响。CFV变化至射流入口速度的40%，偏置射流的高度在射流宽度的5至11倍之间变化，入口雷诺数取为15000。传热结果表明，沿底部壁面的局部努塞尔数（ ）在喷嘴出口紧邻下游处出现峰值，随后在收敛区域的其余部分持续衰减，然后在合并区域沿流向的短距离内出现小幅上升。在更下游的合并区域， 随下游距离逐渐减小。除合并区域外，在其他两个流动区域（收敛区域和合并区域）未观察到共流的影响。在合并区域，对于给定的偏置比（OR）， 在一定轴向距离内几乎保持恒定，并且随着CFV的增加而减小。由于CFV的增加，平均努塞尔数降低，表明对于较高的CFV值，整体对流换热减少。对平均努塞尔数（ ）、CFV和OR进行回归分析，得到了在OR = 5 - 11和CFV = 0 - 40%范围内形式为的相关函数。
