Learning Forum

[oncernhan]

Hi all,

I am calculating the total moment of a Vertical Axis Wind Turbine in 2D as shown below (experimenting with only one blade).

I set up the CFD with sliding mesh (grey area) in trasient simulation

I have a question: When I calculate moment coefficient, does ANSYS Fluent already take into account the relative velocity between the blade (rotational velocity) and the wind (inlet velocity)?

To make it clearer, let's denote: V(a/g): Velocity of air with respect to (wrt) the ground a.k.a inlet velocity, V(t/g): Velocity of turbine wrt the ground a.k.a tangential velocity and V(a/t): Velocity of air wrt turbine 

V(a/g) = V(t/g) + V(a/t) - In vector notation

In other words, does ANSYS Fluent automatically calculate Cm, Cl and Cd based on the relative velocity (Va/t)?

 I can extract Cm versus flow time but I'm not sure how ANSYS Fluent calculate Cm (as well as Cd and Cl) when there is a sliding mesh involved.

Thank you very much. 

[Rob]

It should calculate based on the velocity (relative) on the blades: check the User's Guide for the calculation/equations/definition and follow the links.  You may find forces & moments to be more useful than the coefficients: again check those definitions as they're a function of the reference values.