Zhou ZiDan, Wang ShengKun, Yan ZeXiang, Wang DaoYuan, Deng JinJun, He Yang, Yuan WeiZheng
Key Laboratory of Micro/Nano Systems for Aerospace, Ministry of Education and Shaanxi Key Laboratory of Micro and Nano Electromechanical Systems, School of Mechanical Engineering, Northwestern Polytechnical University, Xi'an 710072, P. R. China.
ACS Appl Mater Interfaces. 2021 Nov 10;13(44):53155-53161. doi: 10.1021/acsami.1c13456. Epub 2021 Oct 28.
Riblets inspired by shark skin exhibit a great air drag reduction potential in many industries, such as the aircraft, energy, and transportation industries. Many studies have reported that blade riblets attain the highest air drag reduction ability, with a current limit of ∼11%. Here, we propose multilayer hierarchical riblets (MLHRs) to further improve the air drag reduction ability. MLHRs were fabricated via a three-layer hybrid mask lithography method, and the air drag reduction ability was studied in a closed air channel. The experimental results indicated that the maximum air drag reduction achieved with MLHRs in the closed channel was 16.67%, which represents a 52% higher reduction than the highest previously reported. Conceptual models were proposed to explain the experiments from a microscopic perspective. MLHRs enhanced the stability of lifting and pinning vortices, while vortices gradually decelerated further, reducing the momentum exchange occurring near the wall. This verified that MLHRs overcome the current air drag reduction limit of riblets. The conceptual models lay a foundation to further improve the air drag reduction ability of riblets.
受鲨鱼皮启发的脊状结构在许多行业，如航空、能源和交通运输行业，展现出巨大的降低空气阻力潜力。许多研究报告称，叶片状脊状结构具有最高的降低空气阻力能力，目前的极限约为11%。在此，我们提出多层分级脊状结构（MLHRs）以进一步提高降低空气阻力的能力。MLHRs通过三层混合掩膜光刻法制造，并在封闭空气通道中研究其降低空气阻力的能力。实验结果表明，在封闭通道中MLHRs实现的最大空气阻力降低率为16.67%，比之前报道的最高值高出52%。提出了概念模型从微观角度解释实验。MLHRs增强了升力和钉扎涡旋的稳定性，同时涡旋进一步逐渐减速，减少了壁面附近发生的动量交换。这证实了MLHRs克服了目前脊状结构降低空气阻力的极限。这些概念模型为进一步提高脊状结构的降低空气阻力能力奠定了基础。
