Hi everyone,
I'm trying to calculate induction and forces on a wind turbine (modeled using ALM) using the velocities obtained from CFD. The domain is set in such a way that zdirection is streamwise (flow) direction, and x as well as y (xy plane is where rotor plane) are tangential directions. I was hoping if someone could clarify a few points:
1. Does the following relation for tangential velocity hold true > V_tan = sqrt(Vx_r^2 + Vy_r^2) + omega*r*R? where Vx_r is the xvelocity at a node inside the rotor region, Vy_r is the yvelocity at a node inside the rotor region, omega is the rotation speed of a blade in rad/s, r is the distance of the node from the center of the rotor normalized by rotor radius and R is the rotor radius.
2. Does the following relation for tangential induction hold true > b = sqrt(Vx_r^2 + Vy_r^2)/(omega*r*R)?
Thank you in advance!
Relation between CFD and BET velocities
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Re: Relation between CFD and BET velocities
Dear Abhishek,
In both equations, I would expect that instead of the vector magnitude, that you'd want to project the tangential flow velocity normal to the blade axis, i.e., replace
with
in both equations, where,
xhat = unit vector along x
yhat = unit vector along y
nhat = unit vector normal to the blade axis in the xy plane
dot = the vector dot product
Best regards,
In both equations, I would expect that instead of the vector magnitude, that you'd want to project the tangential flow velocity normal to the blade axis, i.e., replace
Code: Select all
sqrt(Vx_r^2 + Vy_r^2)
with
Code: Select all
{ vx_r*xhat + vy_r*yat } dot nhat
in both equations, where,
xhat = unit vector along x
yhat = unit vector along y
nhat = unit vector normal to the blade axis in the xy plane
dot = the vector dot product
Best regards,
Jason Jonkman, Ph.D.
Senior Engineer  National Wind Technology Center (NWTC)
National Renewable Energy Laboratory (NREL)
15013 Denver West Parkway  Golden, CO 80401
+1 (303) 384 – 7026  Fax: +1 (303) 384 – 6901
nwtc.nrel.gov
Senior Engineer  National Wind Technology Center (NWTC)
National Renewable Energy Laboratory (NREL)
15013 Denver West Parkway  Golden, CO 80401
+1 (303) 384 – 7026  Fax: +1 (303) 384 – 6901
nwtc.nrel.gov
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