有凸起表面上旋转蒸汽-水两相流的流体动力学:形状优化和温度升高对减阻的影响

Q1 Chemical Engineering
Afrasyab Khan , Khairuddin Sanaullah , Andrew Ragai Henry Rigit , Atta Ullah
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引用次数: 1

摘要

本文研究了带凸板对旋转蒸汽-水两相流的减阻作用。研究了具有三角形、正弦和梯形形状的不同类型的突出物。在尺寸和方向上进行了变化和修改(沿着或穿过,平装或突出到旋转流中),以测试这些突出物的有效性。在5巴进气压力和转速范围从360到1440的情况下,梯形结构提供了最有效的减阻效果。从凸起附近流体区域的PIV图像还发现,梯形凸起的减阻主要是由于凸起上方形成了二次流结构。一方面,相邻突起之间的横向间距创造了增强和膨胀的区域,以对抗来自主要旋转核心流体的较高相反惯性力。而在另一方面,这些间距证明了轴向延伸的涡在突出尖端以上的影响。通过观察流体介质温度升高的影响,还研究了进一步的减阻趋势。在温度升高25-60 °C的情况下,梯形突起可将阻力降低1.3%至1.6%。在努塞尔数上升的影响下,减阻曲线呈上升趋势。这种趋势归因于粘度的降低。而在普朗特数增大的影响下,阻力减小呈减小趋势,这主要是由于边界层压降和摩擦压降的增大所致。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
Hydrodynamics of the swirling steam-water two-phase flows over a surface with protrusions: Shape optimization and effect of rise in temperature on drag reduction

The current study studies the drag reduction offered by the plate with protrusions to the swirling steam-water two-phase flows. Protrusions of different types, having triangular, sinusoidal, and trapezoidal shapes, are investigated. The variations and modifications were made in the dimensions and orientations (facing along or across, flush-mounted or protruded into the swirling flows), to test the effectivity of these protrusions. At 5 bars of inlet gauge pressure and rpm varying from 360 to 1440, the trapezoidal shape provides the most effective drag reduction. It is also found from the PIV images of the fluid region near the protrusions that the drag reduction in the trapezoidal-shaped protrusions occurs mainly due to the secondary flow structures formation over those protrusions.

On the one hand, the lateral spacing between the adjacent protrusions created the region of strengthening and expansion against the higher opposite inertial forces from the main swirling core fluids. While on the other hand, these spacings justify the impact of the axial elongation of the vortices above the protrusion tips. Further trends in drag reduction have also been investigated by observing the effect of the rise in the temperature of the fluid medium. Reduction in drag from 1.3 to 1.6% is noted using the trapezoidal protrusions for a temperature rise of 25–60 °C. It is also observed that the drag reduction profiles show a rising trend under the influence of the rising Nusselt Number. This trend is attributed to the decrease in viscosity. Whereas under the influence of a rising Prandtl number, the drag reduction shows a decreasing trend, mainly attributed to the rise in the pressure drop at the boundary layers and the pressure drop due to the friction.

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来源期刊
Journal of King Saud University, Engineering Sciences
Journal of King Saud University, Engineering Sciences Chemical Engineering-Fluid Flow and Transfer Processes
CiteScore
12.10
自引率
0.00%
发文量
87
审稿时长
63 days
期刊介绍: Journal of King Saud University - Engineering Sciences (JKSUES) is a peer-reviewed journal published quarterly. It is hosted and published by Elsevier B.V. on behalf of King Saud University. JKSUES is devoted to a wide range of sub-fields in the Engineering Sciences and JKSUES welcome articles of interdisciplinary nature.
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