Nature inspires researchers to explore the surroundings with the aim to come up with novel ideas. Consequently, the passive drag reduction technique of introducing the riblets to the surface of the object in a fluid flow was also bio-inspired. Shark-skin infused longitudinal riblets effects on a fluid flow have been widely investigated since the discovery was made in 1970s. Even though the desired drag reducing performance was captured, due to complications in implementing the technology in real-world applications other options had to be investigated further. Inspired by graceful birdâs flight, researchers found an alternative. Vaguely examined herringbone-type riblets covering the surface of a bird feather might be carrying a huge potential as a way of improving the flow performance over the objects in a fluid flow. By examining the convergent/divergent riblet foils fitted on a bio-inspired pigeon wing model in a wind tunnel, several observations were made. At Reynolds number below 100000 the riblets work as a fluctuations dampening mechanism especially shown at 2D aerofoil model. Furthermore, the increased lift coefficient and reduced drag coefficient was captured at almost all incidence angle for 3D wing model. It was observed that riblets tend to influence the inner structure of the near wake of 2D aerofoil model. The observations made during the experiment notify about the positive effect on a flow introduced by the riblets, and the lessons learned should be a good background for further research within the field.
|Date of Award||1 Aug 2021|
- The University of Manchester
|Supervisor||Andrew Kennaugh (Supervisor) & Shan Zhong (Supervisor)|
- herringbone riblets
- wind tunnel