I am trying to do the simulation over and iced airfoil so I prove that with ice there is a degradation in generated lift.. I will compare the lift curves.. Althoug I hit the great problem, I simulated the iced airfoil and the value of Cl keeps rising even after AoA = 28°...
Here are my conditions:
I made a rotating mesh(inside of it is a airfoil as a rotating wall), inside of a another mesh, which I connected together... so this is how I managed to make the airfoil rotate during every timespet 200 timesteps, ine timestep is 0,005s, rotational speed of mesh is -0,5 rad/s than you make some simple counting 200 timesteps = 28°
I attach also my clean airfoil curve, my iced airfoil curve, the picture of my iced airfoil and the inputs I used for simulating
Thanks to everyone who will reply :)
Maybe you'll find your answer searching under "dynamic stall". I would suggest reducing your pitching rate by reducing the rotational speed of the grid and increasing the time step size, both by a factor of 100. In fact a good technique for this kind of simulation is to use sinusoidal pitching with large amplitude (for example 20+-20° for your case) , and observe the hysteresis. For the fully attached flow the pitching must be slow enough that the hysteresis is zero. The maximum and minimum lift will always have a hysteresis (see also "lift bifurcation"), which can be helpful to make decisions about how sensitive the airfoil is to stall conditions.
I wonder about the attempt to accurately predict C_L with a pure tetrahedral mesh, i.e. no distinct boundary layer mesh. But maybe this is a limitation of the icing model in Fluent, where I'm currently not aware of? But this way the boundary layer is not accurately predicted for sure and forces corresponding to lift of an airfoil are very sensitive to that.
Regards,
Dr. Th. Frank.
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