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The wind tunnel test has been performed at the HDG wind tunnel, which is a closed return circuit with a closed test section of 0.6 x 0.6 m. (width x height) and 1 m. length, and a contraction ratio of 5.85. This tunnel can be pressurized up to 100 bars to achieve high Reynolds numbers. The wind tunnel speed is controlled by rpm regulation of the constant pitch fan in the range from 3.5 to 35 m/s, which allows for Reynolds number effect simulations with negligible Mach influence as it stays always below 0.1.
The test section used for the measurements is a dedicated 2D test section where the model is horizontally installed in the mid part into a remote controlled alpha mechanism capable of performing 360º of angular setting of the model. Top and bottom wall centerlines are equipped with 23 pressure taps each, equally distributed over the whole length of the test section, which can be used to calculate wall interference properties

A 150 mm. chord 2D model reproducing the shape of the TU-Delft DU00-W-212 airfoil was manufactured out of steel. The trailing edge thickness was increased to a 0.333% of the chord in order to allow for pressure tap installation in the trailing edge.
The model was equipped with 90 pressure taps with a diameter of 0.2 mm at the mid span. To avoid pressure readings being influenced by the taps, taps were aligned with a minimum angle to the chord of 10 degrees. Minimum distance of the center of the pressure taps was designed to be 2 mm, to allow for tube connection inside the model. Pressure taps were distributed to catch the predicted main flow features at operating conditions of the designed airfoil.
The model is installed in the test section center and rotates around the point at 1/3 of the chord from the leading edge.

Data Provider: 

AVATAR project


Besides the pressure taps on the model, a wake rake with 118 total and 8 static pressure probes was installed around 2 chords downstream of the trailing edge of the model. Using a traversal mechanism it can be moved from centerline to the vicinity of one sidewall. As the model pressure taps of the model are at the mid span, the wake rake useful range to determine undisturbed drag is limited from 100 to 200 mm out of the centerline (y = -100 to - 200 mm in test section coordinate system). The wake rake covers 300 mm in height around the center, allowing for the evaluation of the wake even at high angles of attack
Lift and Pitching Moment Coefficients were calculated by integration of the pressure distribution over the airfoil. Drag was calculated from the flow loss of momentum by integrating the total and static pressures in the airfoil wake.

Measurement Campaign: 

The tests have been performed at 5 different Reynolds numbers: 3, 6, 9, 12 & 15 million, and at Mach numbers always below 0.1. For some Reynolds numbers tests have been performed at different Mach numbers, i.e. using different tunnel total pressure. For all the testing conditions the turbulence intensity level of the flow is always below 0.5%.
Each polar started at 0º angle of attack to do the positive angles sweep up to the maximum positive angle of attack, then the 0º was repeated to start the negative angles sweep to the maximum negative angle of attack. After that, some angles of attack were measured again to check repeatability. Classical corrections following the formulas of Allen and Vincenty, as well as corrections obtained from wall pressure distribution were calculated for each data point. All the data presented have the corrections applied


The data correspond to 7 test cases:

1. Reynolds number 3 million, Mach number 0.074
2. Reynolds number 6 million, Mach number 0.055
3. Reynolds number 6 million, Mach number 0.029
4. Reynolds number 9 million, Mach number 0.083
5. Reynolds number 9 million, Mach number 0.043
6. Reynolds number 12 million, Mach number 0.058
7. Reynolds number 15 million, Mach number 0.081

For each case, there is one data file containing the aerodynamic force coefficients data for the measured angles of attack (AoA), and several pressure coefficients (Cps) files (one for each AoA) containing the pressure data read at each model pressure tap.

Aerodynamic force coefficients file:
This file contains the value of the aerodynamic coefficients (lift, drag and pitching moment) for all the measured angles of attack. It also contains the instant value of Reynolds and Mach numbers at each angle of attack.
The values are organized by columns. Every row corresponds to a particular measured point at a certain angle of attack.
The header indicates the type of data contained at each column:
Pnt: number of point
    Alpha: Angle of attack
    CL: Lift coefficient
    CD: Drag coefficient
    Cm: Pitching Moment coefficient
    L/D: Lift to Drag ratio
    Rey: Reynolds number
    Ma: Mach number
The name of these files contains the value of the Reynolds and Mach numbers of their corresponding case, and ends with “_Coef.txt”:

Reynolds number (in millions)                  Mach number

Pressure coefficients files:
There is one pressure file for each measured point at each case.
The first line of the file shows the angle of attack, Reynolds and Mach number values for the corresponding point.
The second line is the header of the pressure coefficients data. These data are organized in three columns:
    x [m]: is the x coordinate of the pressure tap
    z [m]: is the z coordinate of the pressure tap
    Cp [-]: is the static pressure coefficient measured at the pressure tap.
Every line contains then the pressure coefficient values of each of the 90 model pressure taps.
The name of the files contains the value of Reynolds and Mach numbers, followed by text ‘Cps’ and the number of the measured point as it appears in the force coefficient file.

Reynolds number (in millions)            Mach number         nº of point


Ceyhan Ozlem, Pires Oscar, & Munduate Xabier. (2017). AVATAR HIGH REYNOLDS NUMBER TESTS ON AIRFOIL DU00-W-212 [Data set]. Zenodo. DOI



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