Study on stable thrust of separated undulating fins

• Published in: Ocean engineering 2024-08, Vol.306, p.118046, Article 118046
• Main Authors: Li, Guanghao, Liu, Guijie, Ma, Penglei, Li, Gongbo, Fang, Xin
• Format: Article
• Language: English
• Subjects: Biomimicry; Flow field analysis; Fluid dynamics experiment; Thrust stability; Undulating fins
• ISSN: 0029-8018; 1873-5258
• DOI: 10.1016/j.oceaneng.2024.118046

Constrained by their inherent motion characteristics, undulating fins generate fluctuating thrust during movement, which is disadvantageous for precise underwater positioning and control. Drawing inspiration from the principles of biomimicry and leveraging the excellent maneuverability and propulsion capabilities of dragonflies, this study establishes a separated undulating fins model based on the dragonfly's unique front and rear wing structures. The impact of different phases of the separated undulating fins on thrust is studied by numerical simulation methods and quantitatively evaluate thrust stability using the range and standard deviation. Refining relevant theoretical derivations, the mapping relationship between the phase and thrust stability is established. The intrinsic mechanism behind the generation of stable thrust by separated undulating fins is revealed through flow field analysis. A new undulating fin validation platform is designed and constructed, with experimental results demonstrating a good concordance with numerical simulation outcomes. The study reveals that separated undulating fins can effectively reduce thrust fluctuations, with the range of thrust being only 48% of that of traditional undulating fins and the standard deviation being only 35% of that of traditional undulating fins. This research provides a novel approach and theoretical support for the precise control of underwater robots equipped with undulating fins. •Propose a novel method for reducing the oscillatory nature of thrust in traditional undulating fins.•Provided methodologies and criteria for evaluating the stability of thrust.•Uncovered the mapping patterns of relevant parameters on thrust influence.•Revealed the intrinsic mechanisms through which discrete undulating fins can enhance thrust stability.