近壁集中翼型格栅实现湍流管流的净减阻

中文摘要 AI 辅助

湍流管流的摩擦阻力造成了水和天然气输送系统的巨大能耗。整流器可通过抑制湍流来降低该阻力，但通常会产生超过减阻量的压力损失；同样，管道内安装的大涡破碎装置也未实现净减阻。本研究采用NACA0006翼型格栅作为整流器以抑制压力损失，通过数值模拟评估其净减阻效果，模拟采用轴对称雷诺平均纳维-斯托克斯方程的k-ω剪切应力输运模型，结合周期性边界条件。该模型已通过充分发展的湍流管流及此前管道内大涡破碎装置的实验验证。在对应雷诺数（Re）约为10^5的压差下，近壁集中的同心环格栅图案（轴向间距0.5m）使流量提升最高达9.0%，且在5×10^4≤Re≤2×10^5范围内流量提升始终为正。该格栅图案使面积积分的雷诺剪切应力降低29%，并使速度剖面更接近层流分布。近壁布置的有效性与Fukagata-Iwamoto-Kasagi恒等式一致，该恒等式对近壁处的雷诺剪切应力赋予更高权重。

英文摘要

The frictional drag of turbulent pipe flow is responsible for enormous energy consumption in water and natural gas distribution systems. Flow straighteners can reduce this drag by suppressing turbulence, but they generally induce a pressure loss that exceeds the reduction; similarly, large-eddy breakup devices installed in pipes have not achieved a net drag reduction. In this study, a grid of NACA0006 airfoils was adopted as a flow straightener to suppress the pressure loss, and its net drag reduction was evaluated by numerical simulations using the $k$-$ω$ shear stress transport model of the axisymmetric Reynolds-averaged Navier-Stokes equations with periodic boundary conditions. The model was validated against fully developed turbulent pipe flow and a previous experiment on a large-eddy breakup device in a pipe. Under a pressure difference corresponding to a Reynolds number ($\mathit{Re}$) of approximately $10^5$, a grid pattern of concentric rings concentrated near the wall at an axial spacing of 0.5 m increased the flow rate by up to 9.0%, and the flow rate increase remained positive for $5 \times 10^{4} \leq \mathit{Re} \leq 2 \times 10^{5}$. The grid pattern reduced the area-integrated Reynolds shear stress by 29% and brought the velocity profile closer to a laminar one. The effectiveness of the near-wall placement is consistent with the Fukagata-Iwamoto-Kasagi identity, which weights the Reynolds shear stress more heavily closer to the wall.

发表机构

• National Institute of Technology, Yonago College（米子工业高等专门学校）

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