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Vortex Generators - NTUA t18 Airfoil

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Scope

Tests concern the flow past VGs on an airfoil at Re = 0.87e6. Test details are given in the relevant Test Case. The input data are the airfoils and VG geometries as well as the test conditions. )

Data Accessibility

Data are freely available to everyone under a Creative Commons Attribution 4.0 International License.

Objectives

The objective of this benchmark is to validate different VG modelling approaches against experimental data.

Input data

Tests concern the flow past VGs on an airfoil at Re = 0.87e6. Test details are given in the relevant Test Case. The input data are the airfoils and VG geometries as well as the test conditions.

Validation data

The validation data are:

  1. Pressure distribution along the wing chord for the examined incidence range for the cases with and without VGs

  2. Force and drag coefficient polars for the cases with and without VGs

  3. Velocity, vorticity and Re stress data on three planes normal to the flow and five planes normal to the wing span for the case without VGs, as shown in Figure 1, for the α = 10° case.

  4. Velocity, vorticity and Re stress data on three planes normal to the flow for the case with VGs as shown in Figure 2, for the α = 10° case.

Figure 1: Stereo PIV measurement planes for no VGs case. Planes normal to the flow are shown with solid green line. The red dotted line shows the planes normal to the wing span.

Figure 2: Stereo PIV measurement planes for the VG case. Planes A, B and C are shown with solid green line. The axes are shown twice, once non-dimensionalized with the wing chord (c) and once with the VG height (h). In the latter case the x axis starts at the VG TE.

The provided pressure data are included in the following file:

  • Pressure measurements.xlsx
    • The first four sheets contain the pressure distribution along the wing chord for the two cases
    • The fifth sheet contains the force and drag coefficient polars for all cases

The provided Stereo PIV data are included in two separate files, one for each case. The files are named No VGs.dat and VGs at 0.3c.dat and are Tecplot input files. The variables are listed in Table II. Velocities are non-dimensionalized with free stream velocity, vorticity with chord divided by free stream velocity and Reynolds stresses with free stream velocity squared.

Variable name

Variable

U normalized

Normalized streamwise velocity

V normalized

Normalized vertical velocity

W normalized

Normalized spanwise velocity

u'v'/Uinf^2

Normalized u'v' shear stress

u'w'/Uinf^2

Normalized u'w' shear stress

v'w'/Uinf^2

Normalized v'w' shear stress

u'u'/Uinf^2

Normalized u'u' normal stress

v'v'/Uinf^2

Normalized v'v' normal stress

w'w'/Uinf^2

Normalized w'w' normal stress

Normalized Vorticity

Normalized Vorticity

Table II: Variables included in the provided data files.

Model runs

The numerical simulations should provide full polars for the cases with and without VGs. If a 3D model is used for VG modelling the flow field data (velocity, vorticity Re stress) should also be provided.

Output data

The following name convention is specified for the polar and pressure data:

[CodeName]_[case]_[content].txt

For example, a valid file name would be:

NTUA_MaPFlow_noVGs_polar.txt

For the flow field data the following naming convention should be used

[CodeName]_[case].plt

where:

[CodeName]

is the code name of the set of results provided

[case]

Could be one of the following options:

noVG” for the clean case,

VG” for the case with VGs

[content]

Could be one of the following options:

Polar”

And should contain:

alpha (degrees), CL, CD

Pressure data”

x/c,Cp

Field” *

X, Y, Z, U, V, W, Ox, Oy, Oz, Re_uu, Re_vv, Re_ww, Re_uv, Re_uw, Re_vw

* Field data will be processed with Tecplot. Different planes should appear as separate ZONES

X, Y, Z

are the point coordinates

U, V, W

are the velocity components

Ox, Oy, Oz

are the vorticity components

Re_xx

are the relevant Reynolds stresses

Remarks

The relevant data are analysed in (Manolesos et al., 2013; Manolesos & Voutsinas, 2014; Manolesos et al., 2014; Manolesos & Voutsinas, 2015)

Manolesos, M., Papadakis, G., & Voutsinas, S. G. (2013). Experimental and computational analysis of stall cells on rectangular wings. Wind Energy, 17(6). doi: 10.1002/we.1609

Manolesos, M., Papadakis, G., & Voutsinas, S. G. (2014). Assessment of the CFD capabilities to predict aerodynamic flows in presence of VG arrays. Journal of Physics: Conference Series, 524(1), 012029.

Manolesos, M., & Voutsinas, S. G. (2014). Study of a stall cell using stereo particle image velocimetry. Physics of Fluids, 26(4), 045101. doi: http://dx.doi.org/10.1063/1.4869726

Manolesos, M., & Voutsinas, S. G. (2015). Experimental investigation of the flow past passive vortex generators on an airfoil experiencing three-dimensional separation. Journal of Wind Engineering and Industrial Aerodynamics, 142, 130-148.

Terms and Conditions

No NDA is required

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