Numerical Investigation on Flow Separation Control of Low Reynolds Number Sinusoidal Aerofoils

The paper presents a computational analysis of the characteristics of a NACA 634-021 aerofoil modified by incorporating sinusoidal leading-edge protuberances at Re = 14,000. The protuberances are from the tubercles of the humpback whale flipper with leading edge acting as passive-flow control devices that improve performance and manoeuvrability of the flipper. They are characterized by an amplitude and wavelength of 12% and 50% of the aerofoil chord length respectively. Three-dimensional CFD on the modified aerofoil oscillating about a point located on the centreline at quarter-chord has been performed with the frequency and amplitude of oscillation being 4Hz and 10 deg respectively. In addition to the lift and thrust coefficients, near wall flow visualisations and the shedding of vortices during oscillations are presented to illustrate the unsteady flow features on the performance of the oscillating flipper. The results show an improvement in the thrust production when compared to previous studies on similar symmetric aerofoil without the leading edge modifications.

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Unsteady CFD Analysis of an Oscillating Aerofoil Inspired by Dragonfly Wings

Ho¹,

New²,

Matare³

2017

Topical Problems of Fluid Mechanics 2017

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An unsteady two-dimensional CFD analysis of an oscillating (dynamically pitching) aerofoil inspired by dragonfly wings was conducted to investigate its aerodynamic and flow characteristics. The aerofoil morphology was an idealised geometry based on the crosssection near the mid-span of a dragonfly wing. The aerofoil was made to oscillate at 2Hz with amplitude of 10° with an upstream flow such that the chord Reynolds number was 14,000. The methodology mirrored a previous study but with slight differences due to the difference in geometry. Complex flow structures near to the aerofoil surface revealed significant effect on lift and drag characteristics. Lift and drag hysteresis indicate that there is net lift generated but no net thrust. Instantaneous lift and drag shows there is a difference in both the negative and positive peak lift and drag values between when the aerofoil is pitching up and when it is pitching down. This is consistent with previous studies. Comparisons with previous studies on oscillating smooth aerofoils do not indicate that such corrugated aerofoils exhibit any advantages. It is possible that any performance enhancements will only manifest itself when operating in tandem with other aerofoils in close proximity such as between the fore and hind-wing of a dragonfly.

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Numerical Investigation on Flow Separation Control of Low Reynolds Number Sinusoidal Aerofoils

Abstract: The paper presents a computational analysis of the characteristics of a NACA 63 4 -021 aerofoil incorporated with sinusoidal leading-edge protuberances at Re = 14,000. I.

Cited by 3 publications

References 8 publications

Flow Control by Hydrofoils with Leading-Edge Tubercles

Flow Control by Hydrofoils with Leading-Edge Tubercles

Effect of Leading Edge Protuberance on Thrust Production of a Dynamically Pitching Aerofoil

Unsteady CFD Analysis of an Oscillating Aerofoil Inspired by Dragonfly Wings

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