Numerical study of passive and active flow separation control over a NACA0012 airfoil

“…If vortex generators with the height, h, between 10% and 50% of the boundary layer thickness are placed less than 100h upstream of the separation point, the size of the separation bubble is reduced resulting in a thinner turbulent boundary layer and reduced drag. On the other hand, at a small angle of attack (6 • ), no significant lift augmentation or drag reduction on NACA 0012 airfoil has been found [153].…”

Section: Turbulence and Vortex Generators (Classification: Passive Gmentioning

confidence: 99%

“…To delay the separation, the vortex generators should be placed close to the natural separation point [146,153,154]. The vortex generators have been shown to delay the dynamic stall of wind turbines if placed at the leading edge [145], to weaken the secondary flow in compressor cascade passage if placed at the endwall [74], and to induce reattachment if placed on the suction side of the compressor blade [74,155].…”

Section: Turbulence and Vortex Generators (Classification: Passive Gmentioning

confidence: 99%

Flow Control Methods and Their Applicability in Low-Reynolds-Number Centrifugal Compressors—A Review

Tiainen

Grönman

Jaatinen-Värri

et al. 2017

IJTPP

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Abstract:The decrease in the performance of centrifugal compressors operating at low Reynolds numbers (e.g., unmanned aerial vehicles at high altitudes or small turbomachines) can reach 10% due to increased friction. The purposes of this review are to represent the state-of-the-art of the active and passive flow control methods used to improve performance and/or widen the operating range in numerous engineering applications, and to investigate their applicability in low-Reynolds-number centrifugal compressors. The applicable method should increase performance by reducing drag, increasing blade loading, or reducing tip leakage. Based on the aerodynamic and structural demands, passive methods like riblets, squealers, winglets and grooves could be beneficial; however, the drawbacks of these approaches are that their performance depends on the operating conditions and the effect might be negative at higher Reynolds numbers. The flow control method, which would reduce the boundary layer thickness and reduce wake, could have a beneficial impact on the performance of a low-Reynolds-number compressor in the entire operating range, but none of the methods represented in this review fully fulfil this objective.

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“…As such, historically it has been difficult to perform such simulations for large Reynolds numbers, however, with the continual increase in computational resources available these are becoming more common. 15,16,17 The Lattice-Boltzmann method 18 has also been used to produce time-dependent flow simulations around VGs.…”

Section: Iia High Fidelity Physicsmentioning

confidence: 99%

An Aerodynamic Model for Vane-Type Vortex Generators

Poole

Bevan

Allen

et al. 2016

8th AIAA Flow Control Conference

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General rightsThis document is made available in accordance with publisher policies. Please cite only the published version using the reference above. Full terms of use are available: http://www.bristol.ac.uk/pure/about/ebr-terms A new, physics-based model is presented for flows around vortex generators. The model uses a modified lifting-line method with added physics to account for boundary layer flow. The lifting-line method is extended to also include a vortex lift component and these two components are used to calculate the strength of a vortex shed from an isolated vortex generator. The circulation model is developed further to be used within a CFD framework in a source term approach. Validation is presented, first for the circulation model against a suite of experimental tests for isolated vortex generators where the vortex strength is measured. Excellent agreement is shown that is of the order of the experimental error; 5%. Second, the source term model is validated on a flat plate mounted vortex generator problem, and compared to fully-gridded simulations and the commonly used Bender-Anderson-Yagel model. Again, the new method shows excellent agreement, matching well the circulation decay and velocities downstream of the VG.

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Numerical study of passive and active flow separation control over a NACA0012 airfoil

Cited by 103 publications

References 35 publications

Flow-Control Effectiveness of Convergent Surface Indentations on an Aerofoil at Low Reynolds Numbers

Flow-Control Effectiveness of Convergent Surface Indentations on an Aerofoil at Low Reynolds Numbers

Flow Control Methods and Their Applicability in Low-Reynolds-Number Centrifugal Compressors—A Review

An Aerodynamic Model for Vane-Type Vortex Generators

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