Heated horizontal plane jets find wide applications in engineering appliances such as air curtains and discharge of industrial effluents. In the present study, experimental investigations are conducted on a heated horizontal plane jet with the Reynolds numbers in the transitional regime, using a hotwire anemometer. In the far to very far-field (20 < x/d < 100) centreline velocity decay and jet spread increases faster with the decrease of Reynolds number. This is because, with the increase of Reynolds number, the turbulent kinetic energy is distributed on a broadband of scales. As a result, larger scales, which are responsible for increased entrainment, get weaker. The shifting of the centre plane generally occurs in the far region for low Reynolds number jets. A comparison with the result of an isothermal jet at similar Reynolds numbers from the literature at identical conditions shows that the turbulence intensity is decreased due to heating. Centreline velocity decays slowly and half-width increases marginally for a heated jet when compared with an isothermal jet. The effect of heating is prominent for low Re jets. Spectral development shows a delayed transition due to heating. Probability density function plots reveal lack of equilibrium and presence of large-scale eddies in the flow field.

中文翻译：

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雷诺数和浮力对过渡区平面射流流动发展影响的实验研究

加热水平面射流广泛应用于工程设备，如空气幕和工业废水排放。在本研究中，使用热线风速计对雷诺数处于过渡状态的加热水平面射流进行了实验研究。在远场到非常远场 (20 < x/d < 100) 中，中心线速度衰减和射流扩散随着雷诺数的减小而增加得更快。这是因为，随着雷诺数的增加，湍流动能呈宽带尺度分布。结果，导致夹带增加的较大尺度变得更弱。中心平面的移动通常发生在低雷诺数射流的远区。与文献中相同条件下类似雷诺数的等温射流结果的比较表明，湍流强度因加热而降低。与等温射流相比，加热射流的中心线速度衰减缓慢，半宽度略有增加。对于低 Re 射流，加热的影响是显着的。光谱发展显示由于加热而延迟转变。概率密度函数图显示流场中缺乏平衡和存在大尺度涡流。光谱发展显示由于加热而延迟转变。概率密度函数图显示流场中缺乏平衡和存在大尺度涡流。光谱发展显示由于加热而延迟转变。概率密度函数图显示流场中缺乏平衡和存在大尺度涡流。