This paper presents the results of a numerical study of the effect of a positive longitudinal pressure gradient in a pipe with a sudden expansion on the turbulent two-phase flow structure and local heat transfer. It is shown that a longitudinal pressure gradient has a significant effect on flow characteristics and heat transfer in separated gas-droplet flow. Increasing the diffuser opening angle leads to a significant increase in the degree of flow turbulence (almost twofold increase compared to gas-droplet flow in a pipe with a sudden expansion at $$\varphi=0^\circ$$ ). It is found that in the flow under study, the length of the recirculation zone is significantly increased in comparison with separation gas-droplet flow at $$\varphi=0^\circ$$ and the point of maximum heat transfer rate is shifted downstream. Furthermore, the coordinate of the point of maximum heat transfer rate does not coincide with the coordinate of the reattachment point of the detached two-phase flow.

中文翻译：

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突然膨胀的轴对称扩散器中的气滴流动结构和传热

本文介绍了对突然膨胀的管道中正纵向压力梯度对湍流两相流结构和局部传热的影响的数值研究结果。结果表明，纵向压力梯度对分离的气体-液滴流中的流动特性和传热具有显着影响。增加扩散器开度会导致流动湍流程度显着增加（与在 $$\varphi=0^\circ$$ 处突然膨胀的管道中的气体液滴流相比，增加了几乎两倍）。发现在所研究的流动中，与分离气滴流相比，在$$\varphi=0^\circ$$时，再循环区的长度显着增加，并且最大传热率点向下游移动. 此外，