Vortex generator unsteady effect

Wind & Water Airfoils
1

Hi All,

Does anyone have suggestion on modelling the unsteady effect of Vortex Generators/aerodynamic add-ons on the aeroelastic load calculation. How could we use kind of look up table for transient loading of 2Dsection and use that the hystresis in OpenFAST?

Thanks!

Best regards

2

Dear @Ramesh.Kumar,

Can you clarify what information you already have on the influence of vortex generators / aerodynamic add-ons? Do you have steady and unsteady airfoil polar data from wind tunnel experiments or high-fidelity modeling solutions with the vortex generators / aerodynamic add-ons included?

Best regards,

3

Dear @Jason.Jonkman

Thanks for quick look at my post.

Yes, I have the steady polar as well as the transient load history (Cl and Cd) from with wind tunnel data. I can also produce the section load from CFD simulation (modellinf extruded airfoil with add-ons on it). I am sure the vortex induced vibration with broken shear layer would results in lower amplitude oscillations.

If I just change the polar with upgrade does not really does the job…it acts like a different airffoil having higher Cl/Cd or different polar. Could you please suggest how could we model the effects of add-on on the dynamic loads (fatigue) capturing the true unsteady effect it creates.

Best regards

4

Dear @Ramesh.Kumar,

I would say that the typical approach would be to calibrate the unsteady airfoil aerodynamic model of AeroDyn to match the known hysteresis (from wind tunnel experiments) of the airfoil with vortex generators / aerodynamic add-ons included.

Best regards,

5

Dear @Jason.Jonkman

Thanks for the suggestion.

  • I have the time history at difference angle of attack ( not the hystresis as in moving airfoil…like pitching airfoil)
  • Most of the constant unsteady parameters of the input files are default and I did calculate using the script which @Roger.Bergua provided (i.e., AeroDyn_UA_coefficients.m) and these unsteady parameters are based on steady polar.
  • Is above correct when you say calibrate the unsteady model? Could you please explain bit more which parameters and how could I do that?
    unsteady_parameter
    unsteady_parameter1106Ă—697 129 KB

Best regards
Ramesh

6

Dear @Ramesh.Kumar,

I was referring to calibration of the unsteady parameters to match the unsteady hysteresis loop associated with a moving airfoil, but it doesn’t sound like you have such data to calibrate against. Unsteadiness resulting from the vortex generators / aerodynamic add-ons of a static airfoil is not modeled by AeroDyn.

Best regards,

8

for example the the run/setup files for the below paper.

Development and Validation of a New Unsteady Airfoil Aerodynamics Model Within AeroDyn | AIAA SciTech Forum

9

Dear @Jason.Jonkman ,

I managed to get the Cl and Cd hysteresis with UAMod=3 at 10m/s steady wind for IEA-15MW model as below. The pattern seems not quite right. How did you achieve the Cl, Cd plots in above reference.

image
image1322Ă—621 104 KB

Best regards
Ramesh

10

Dear @Ramesh.Kumar,

A driver for running the unsteady airfoil aerodynamics model standalone for a single airfoil, uncoupled from other parts of AeroDyn or OpenFAST, has been developed, as documented here: 4.2.1.8. Unsteady Aerodynamics — OpenFAST v3.5.3 documentation.

Best regards,

11

Dear @Jason.Jonkman

Thanks a lot, I managed to run the pitching cases.

Best regards
Ramesh

1 Like