基于表面层级结构的亲水微槽道减阻特性研究

RESEARCH ON DRAG REDUCTION CHARACTERISTICS OF MICROCHANNELS BASED ON SURFACE COMPOSITE STRUCTURES

随着全球能源危机日益加剧,流动减阻研究引起众多学者注意.超疏水微槽道内表面的层级结构有助于形成气液界面,从而实现减阻,但亲水微槽道内表面层级结构的减阻特性尚不清楚.文章结合数值模拟和实验研究,对亲水微槽道内空间立柱结构(transverse post structure,TPS)、二次内凹的空间立柱结构(doubly reentrant transverse post structure,DR-TPS)和二次内凹的微脊结构(doubly reentrant surface groove structure,DR-SGS),共3种表面层级结构的减阻特性进行了研究.研究发现,当气液界面稳定时,3种结构均有一定的减阻效果,其中,TPS和DR-TPS减阻效果相似,DR-SGS减阻效果最好,减阻率最高可达11.8%.经模拟发现,TPS和DR-TPS减阻效果低于DR-SGS的原因是它们的层级结构附近存在涡结构,造成了局部增阻.此外,流速对于3种结构的减阻效果也有影响,当流速较大时,结构中的气液界面容易失稳,从而使减阻效果减弱甚至出现增阻现象,TPS,DR-TPS和DR-SGS 3种结构维持气液界面稳定的能力依次增强.

Amidst the escalating global energy crisis,there is a growing scholarly focus on flow reduction.The composite structures of superhydrophobic microchannels facilitate the formation of gas-liquid interfaces,consequently achieving drag reduction.Nevertheless,the drag reduction characteristics of composite structures in hydrophilic microchannels remain uncertain.This study integrates numerical simulation and experimental research to explore the drag reduction properties of three surface composite structures:transverse post structure(TPS),doubly reentrant transverse post structure(DR-TPS),and doubly reentrant surface groove structure(DR-SGS).Our investigation reveals that under stable gas-liquid interface conditions,all three structures demonstrate drag reduction properties.Notably,TPS and DR-TPS yield similar drag reduction effects,while DR-SGS exhibits the most significant drag reduction effect,reaching a maximum reduction rate of 11.8%.Simulation results indicate that the drag reduction effect of TPS and DRTPS is inferior to that of DR-SGS due to localized drag increase caused by vortex structures within the flow field.Additionally,the flow rate impacts the drag reduction effectiveness of the three structures.Higher flow rates make the gas-liquid interface within the structure susceptible to collapse,thereby diminishing the drag reduction effect and potentially leading to increased drag.Furthermore,the sequential increase in the ability of TPS,DR-TPS,and DR-SGS structures to maintain gas-liquid interface stability is observed.