Vortex-Generator Model and Its Application to Flow Control

Jirasek, Adam

doi:10.2514/1.12220

Cited by 110 publications

(77 citation statements)

References 9 publications

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“…However, non-aerodynamic constraints such as material property, manufacturability, and stealth capability in military applications often conflict with the aerodynamic constraints, and either passive or active flow control is required to overcome the difficulty. Passive control devices, for example, vortex generators (Jirasek, 2004), have proven to be effective in delaying flow separation under some conditions. However, they can introduce a drag penalty when the flow does not separate.…”

Section: Introductionmentioning

confidence: 99%

Active control of flow separation over an airfoil using synthetic jets

You¹,

Moin²

2008

Journal of Fluids and Structures

191

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We perform large-eddy simulation of turbulent flow separation over an airfoil and evaluate the effectiveness of synthetic jets as a separation control technique. The flow configuration consists of flow over an NACA 0015 airfoil at Reynolds number of 896,000 based on the airfoil chord length and freestream velocity. A small slot across the entire span connected to a cavity inside the airfoil is employed to produce oscillatory synthetic jets. Detailed flow structures inside the synthetic-jet actuator and the synthetic-jet/cross-flow interaction are simulated using an unstructured-grid finite-volume large-eddy simulation solver. Simulation results are compared with the 2005 experimental data of Gilarranz et al., and qualitative and quantitative agreements are obtained for both uncontrolled and controlled cases. As in the experiment, the present large-eddy simulation confirms that synthetic-jet actuation effectively delays the onset of flow separation and causes a significant increase in the lift coefficient. Modification of the blade boundary layer due to oscillatory blowing and suction and its role in separation control is discussed. r

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Section: Introductionmentioning

confidence: 99%

Active control of flow separation over an airfoil using synthetic jets

You¹,

Moin²

2008

Journal of Fluids and Structures

191

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“…Reference [6] suggests that this asymptotic behavior is reached for c VG > 5. Reference [8] found that the flow in an S-duct is independent of the value of c VG for values greater than seven. The default value for c VG in Wind-US is 10, but it may be changed by the user.…”

Section: Bay Vortex Generator Modelmentioning

confidence: 99%

Modeling Vortex Generators in a Navier-Stokes Code

Dudek

2011

AIAA Journal

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A source-term model that simulates the effects of vortex generators was implemented into the Wind-US NavierStokes code. The source term added to the Navier-Stokes equations simulates the lift force that would result from a vane-type vortex generator in the flowfield. The implementation is user-friendly, requiring the user to specify only three quantities for each desired vortex generator: the range of grid points over which the force is to be applied and the planform area and angle of incidence of the physical vane. The model behavior was evaluated for subsonic flow in a rectangular duct with a single vane vortex generator, subsonic flow in an S-duct with 22 corotating vortex generators, and supersonic flow in a rectangular duct with a counter-rotating vortex-generator pair. The model was also used to successfully simulate microramps in supersonic flow by treating each microramp as a pair of vanes with opposite angles of incidence. The validation results indicate that the source-term vortex-generator model provides a useful tool for screening vortex-generator configurations and gives comparable results to solutions computed using gridded vanes.

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“…The forces exerted on a fluid by a vortex generator are averagely distributed on every grid cell and are added as source terms into the difference equations when NavierStokes Equations are discretized in this region. It is difficult to locate the grid cells where the VGs should be, so the model was modified by Adam in 2004 with a new name jBAY model [2], in which VGs were replaced by sheets without thickness and the method how to locate the cells was also been improved. Although there is no need to estimate the strength of shedding vortices from the tip of VGs in the first kind of model, forces acted on the flow by VGs are very empirically dependent.…”

Section: Introductionmentioning

confidence: 99%

Modeling of delta-wing type vortex generators

Zhang

Yang

et al. 2011

Sci. China Technol. Sci.

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A numerical model of delta-wing type vortex generator was developed in two steps. The first step was to obtain a parameterized model of the shedding vortex based on delta-wing theory, which relates the geometry parameters and flow field parameters to the strength of shedding vortex which directly decides the source term. In the second step, a method was proposed to add source terms into the flow control equations so that the shedding vortex could be simulated numerically. As soon as the numerical model was completed, two cases: One for a plate and another for an airfoil segment were investigated for test. Comparison showed that the flow field structure and aerodynamic performance agreed well with those obtained from cases with real vortex generators. vortex generators, modeling, source term Citation:

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Vortex-Generator Model and Its Application to Flow Control

Cited by 110 publications

References 9 publications

Active control of flow separation over an airfoil using synthetic jets

Active control of flow separation over an airfoil using synthetic jets

Modeling Vortex Generators in a Navier-Stokes Code

Modeling of delta-wing type vortex generators

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