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QBlade ForumQBlade: Structural DynamicsRegarding proper utilization of a …

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Regarding proper utilization of aeroelastic simulation outputs?

#1 · 19. March 2023, 07:57

Quote from Brian on 19. March 2023, 07:57
Hello,
We have successfully created a turbine and ran an aeroelastic simulation for a VAWT. We are now looking to use the outputs to analyze the components in an nonlinear SOLIDWORKS simulation. This is particularly important for some of our turbine’s features such as the blade-to-torque tube connector and the trust structure that supports the turbine.
Our initial approach was to interpolate the blade shape into a square cross section at both ends of the blade. This would allow the blade ends to easily fit into the connection device we designed. Our simulation plan was to gather internal force data, in Qblade, at the point where the blades become a square cross section. Then, in SOLIDWORKS, we would delete all of the blade, except for the square cross section ends that seat into the connector. We would then read in the internal forces from that final node, into a SOLIDWORKS nonlinear study, as a boundary condition on the face of the square cross section. In your opinion, would this setup allow for an accurate simulation of the displacements, stresses, and strains that arise in the connector, torque tube, and truss structure due to the forces on the blades.
The method outlined above would not allow us to analyze the effects of the forces on the blades of the VAWT in detail. If we were to take the deformation values, obtained from Qblade simulation output data, at key points along the blades, and then read them in as boundary conditions in a nonlinear SOLIDWORKS study, do you believe we could obtain stresses and strains within the blades that are somewhat accurate? If not, would you be willing to provide some suggestions as to how we might start the setup for such a simulation. Note that I have attached our ‘.qpr’ file below. Thank you so much for your time.
Any help would be greatly appreciated.
Thank you in advance.
P.S. If you need the qpr file just let me know since ven in a zipped file, it is too large to attatch to this posting.

Hello,

We have successfully created a turbine and ran an aeroelastic simulation for a VAWT. We are now looking to use the outputs to analyze the components in an nonlinear SOLIDWORKS simulation. This is particularly important for some of our turbine’s features such as the blade-to-torque tube connector and the trust structure that supports the turbine.

Our initial approach was to interpolate the blade shape into a square cross section at both ends of the blade. This would allow the blade ends to easily fit into the connection device we designed. Our simulation plan was to gather internal force data, in Qblade, at the point where the blades become a square cross section. Then, in SOLIDWORKS, we would delete all of the blade, except for the square cross section ends that seat into the connector. We would then read in the internal forces from that final node, into a SOLIDWORKS nonlinear study, as a boundary condition on the face of the square cross section. In your opinion, would this setup allow for an accurate simulation of the displacements, stresses, and strains that arise in the connector, torque tube, and truss structure due to the forces on the blades.

The method outlined above would not allow us to analyze the effects of the forces on the blades of the VAWT in detail. If we were to take the deformation values, obtained from Qblade simulation output data, at key points along the blades, and then read them in as boundary conditions in a nonlinear SOLIDWORKS study, do you believe we could obtain stresses and strains within the blades that are somewhat accurate? If not, would you be willing to provide some suggestions as to how we might start the setup for such a simulation. Note that I have attached our ‘.qpr’ file below. Thank you so much for your time.

Any help would be greatly appreciated.

Thank you in advance.

P.S. If you need the qpr file just let me know since ven in a zipped file, it is too large to attatch to this posting.

#2 · 20. March 2023, 18:48

Hi Brian,

I think that the process that you describe is close to how stresses are obtained in practice. You compute loads with a lower order beam model and then apply these loads to a higher order model to obtain stresses.

Typically you split up these loads into the ultimate loads, the largest loads that the structure will experience during its lifetime, and the fatigue loads, which are oscillating loads that act on the structure for a large number of cycles.

BR,

David

#3 · 20. March 2023, 20:58

Hello,

Thank you for getting back to us. Another question we have is, would we use only the forces, or both the forces and the moments at the tips of the blades to be used as inputs on our connector/ torque tube FEA model? I ask because we are not sure if the forces are causing the moments, or if they are independent in this scenario.

Another issue we are running into is that the simulations are failing during or just after the ramp-up. We are using the fix ramp-up simulation method. If we set the TSR to anything above 3.5, the simulation fails due to what we believe is an incredibly high deformation of the blades, torque tube, and tower. But what is interesting is that if the turbine can survive the ramp-up, the major deformation quickly subsides, and the deformations decrease to a much more acceptable level, on the order of 1 in, during the CFD portion of the simulation.

#4 · 21. March 2023, 15:51

Hi Brian,

yes, you need to apply both the forces and moments to your FEA model.

Regarding the issue with the rampup: During the rampup time to rotor is accelerated to arrive at the specified rpm/TSR once the rampup time is over. If you keep the rampup time fixed and increse the rpm/TSR this means that the acceleration of the rotor is getting larger and larger. Simply try to increase the rampup time – that should solve you problem.

Best,

David