The effects of leading-edge tubercles on dynamic stall

Hrynuk, John; Bohl, Douglas

doi:10.1017/jfm.2020.216

Cited by 41 publications

(8 citation statements)

References 41 publications

(103 reference statements)

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“…Studies in the literature 4,43 indicate that MAVs equipped with leading-edge tubercles on their wings can sustain higher lift beyond the post-stall angle of attack, thereby augmenting their maneuvering capabilities. Additionally, it is well documented that tubercle airfoils offer aerodynamic advantages for wind turbine blades [44][45][46] and helicopter rotor blades. 46 The current study introduces a multi-objective optimization model (as shown in Fig.…”

Section: Methodsmentioning

confidence: 99%

On the investigation of the aerodynamics performance and associated flow physics of the optimized tubercle airfoil

Pinapatruni,

Duddupudi,

Dash

et al. 2024

Physics of Fluids

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In the present study, the evolutionary multi-objective optimization is employed to design the optimum amplitude and wavelength of sinusoidal leading-edge tubercles for the NACA0012 (National Advisory Committee for Aeronautics) airfoil to improve its aerodynamic performance at Reynolds number of 5.0 × 104 than that of the NACA0012 smooth leading-edge or baseline airfoil. Here, the optimum tubercle is found to have an amplitude of 11.71% and a wavelength of 25% of the baseline airfoil chord, respectively. Through a combination of in-house water tunnel experiments and numerical simulations, it is additionally established that the optimized tubercle airfoil exhibits superior lift and reduced drag characteristics compared to the baseline airfoil, particularly in the post-stall high angle of attack regime. Furthermore, it is noticed that the optimized tubercle design enhances the gap between large separation regions or stall cells along the tubercle airfoil span during the post-stall regime. Consequently, a more pronounced attached flow regime is developed between the consecutive stall cells, contributing to the tubercle airfoil's improved aerodynamic characteristics compared to the baseline airfoil. Our investigations also revealed that the formation and arrangement of the stall cells on the tubercle airfoil span are associated with a biased wake mechanism similar to the one observed in the wake of side-by-side arranged circular cylinders.

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Section: Methodsmentioning

confidence: 99%

On the investigation of the aerodynamics performance and associated flow physics of the optimized tubercle airfoil

Pinapatruni,

Duddupudi,

Dash

et al. 2024

Physics of Fluids

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“…Of note, the team noted that the humpback whale is the only baleen whale that relies on manoeuvrability while capturing its prey, hinting at a possible role of tubercles in dynamic situations ( Hain et al, 1982 ; Miklosovic et al, 2004 ). With this biological insight, engineering studies have since confirmed that tubercles act to delay or control dynamic stall ( Hrynuk and Bohl, 2020 ). The mechanism for this improved response is attributed to streamwise vortices that develop off of the crests of each tubercle.…”

Section: Tuberclesmentioning

confidence: 99%

“…The mechanism for this improved response is attributed to streamwise vortices that develop off of the crests of each tubercle. These vortices add energy to the flow, allowing the underlying flow to remain attached even at high angles of attack and, thus, reduce the likelihood of both dynamic and static stall ( Hansen et al, 2010 , 2011 ; Hrynuk and Bohl, 2020 ; Watts and Fish, 2001 ).…”

Section: Tuberclesmentioning

confidence: 99%

Lessons from natural flight for aviation: then, now and tomorrow

Harvey

Croon

Taylor

et al. 2023

Journal of Experimental Biology

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Powered flight was once a capability limited only to animals, but by identifying useful attributes of animal flight and building on these with technological advances, engineers have pushed the frontiers of flight beyond our predecessors’ wildest imaginations. Yet, there remain many key characteristics of biological flight that elude current aircraft design, motivating a careful re-analysis of what we have learned from animals already, and how this has been revealed experimentally, as well as a specific focus on identifying what remains unknown. Here, we review the literature to identify key contributions that began in biology and have since been translated into aeronautical devices or capabilities. We identify central areas for future research and highlight the importance of maintaining an open line of two-way communication between biologists and engineers. Such interdisciplinary, bio-informed analyses continue to push forward the frontiers of aeronautics and experimental biology alike.

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“…Furthermore, the velocity profiles in the wake separation region, in addition to lift coefficients, were calculated as non-constant time-averages and were more consistent with experimental values. Hrynuk et al [13] investigated the effect of leading-edge tubercles on the dynamic stall of an airfoil. It was shown that leading-edge tubercles can delay the dynamic stall of an airfoil.…”

Section: Introductionmentioning

confidence: 99%

Implementation of a PAFV turbulence model for airfoil flow simulation on OpenFOAM

Yan,

Sun,

Sun

et al. 2024

Phys. Scr.

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To further develop a more effective turbulence model and to improve the calculation accuracy of the flow around airfoil, a new PAFV turbulence model has here been constructed by using a deformation rate tensor and the grouping of an average fluctuation velocity. To evaluate the applicability of the PAFV turbulence model, the numerical calculations of flow around the airfoil have here been implemented, which was based on the OpenFOAM calculation platform. On the basis of grid independence research, the model was used to calculate the low-speed flow-around problem for the plano-convex airfoil NACA4412 and the symmetric airfoil NACA0012. It was also compared with the S-A (Spalart-Allmaras) and SST (Shear Stress Transport) k-ω turbulence models. Firstly, the maximum lift angle-of-attack case of the NACA4412 airfoil was calculated. Thereafter, numerical calculations were performed for the flow around the airfoil in the multi-angle-of-attack case of NACA0012 airfoil. The results showed that the NACA4412 airfoil had an obviously separated vortex at the trailing edge of the airfoil at the maximum lift angle of attack. Also, there was a certain velocity loss downstream of the trailing edge, as was calculated by all three models. However, the results of the PAFV turbulence model were found to be better than those of the S-A and SST turbulence models. The three turbulence models showed comparable accuracies for the calculations of the surface pressure coefficients of the NACA0012 airfoil. However, the S-A and SST k-ω turbulence models were slightly better for the calculations of the mean velocity profiles of the NACA0012 airfoil. Also, the PAFV turbulence model was more accurate for the calculations of the lift and drag coefficients. In conclusion, the PAFV model can make effective predictions for the airfoil low-speed flow around the problem at hand, which in turn preliminarily verifies the applicability of this turbulence model for the low-speed flow around airfoil problems.

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The effects of leading-edge tubercles on dynamic stall

Cited by 41 publications

References 41 publications

On the investigation of the aerodynamics performance and associated flow physics of the optimized tubercle airfoil

On the investigation of the aerodynamics performance and associated flow physics of the optimized tubercle airfoil

Lessons from natural flight for aviation: then, now and tomorrow

Implementation of a PAFV turbulence model for airfoil flow simulation on OpenFOAM

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