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OpenFAST / openfast

Main repository for the NREL-supported OpenFAST whole-turbine and FAST.Farm wind farm simulation codes.
http://openfast.readthedocs.io
Apache License 2.0
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Question about blade icing simulation #1891

Closed Wangzhenyu12 closed 8 months ago

Wangzhenyu12 commented 8 months ago

Hello everyone!

What I want to study is blade icing. I know there is no blade icing related module in OpenFAST at the moment, so I simplified it to study the effect of blade airfoil changes on the dynamic response of the structure without considering the mass change due to icing. The icing is set on the upper half of the blades of the 5MW onshore wind turbine, the airfoils are all NACA64_A17, and the ice is concentrated near the leading edge of the airfoils. The maximum thickness of ice divided by the chord length is about 0.3.

I don't need to be very precise in my calculation results. Now I have some questions:

  1. I know the airfoil of the blades after icing, and when I open the NACA64_A17_coords.txt I find that the x/c values are all between 0-1. When I modify the coordinates, do I still have to make sure that new x/c is also between 0-1.
  2. Do I must modify the Cl, Cd, Cm curves in NACA64_A17.dat? If yes, I wonder what is the difference between modifying airfoil coordinates or not under new Cl, Cd, Cm curves?
  3. Do I need to modify BlSwpAC in NRELOffshrBsline5MW_AeroDyn_blade.dat?
  4. Please tell me if there are any other parameters that need to be modified.

Thanks!

jjonkman commented 8 months ago

Dear @Wangzhenyu12,

Here are my answers to your questions:

  1. Yes, the x/c values (X_Coord) should be normalized values between 0 and 1 (inclusive). However, the airfoil shape is used only for visualization, not directly in the aerodynamic calculations of AeroDyn.
  2. Yes, icing will have a direct effect on the airfoil data Cl, Cd, and Cm. These are the main aerodynamic parameters influenced by icing.
  3. AeroDyn blade inputs BlCrvAC and BlSwpAC identify the reference point of the aerodynamic forces computed by AeroDyn. I would not expect these to change with icing, but I supposed that depends on how you are changing Cl, Cd, and Cm.
  4. In addition to a decrease in aerodynamic performance (through modification of Cl, Cd, and Cm), I would expecting icing to increase the blade masses (within the structural module, not AeroDyn).

Best regards,

Wangzhenyu12 commented 8 months ago

Dear jjonkman Thanks for your quick reply, which solved my problems perfectly.

Best regards,