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Calculating pressure fields and using them to modelling loads on an object?

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Message 1 of 3
dylanad
433 Views, 2 Replies

Calculating pressure fields and using them to modelling loads on an object?

Hi all,

I'm nearing the end of a large, somewhat self-directed undergrad project, and have hit a dead-end very late in the piece because of some very shonky approximations I made (or didn't think about). Basically, I'm trying to model (over 360 degrees) the loads on the blades of a cross-flow, vertical-axis tidal turbine, similar to this: *this*, but in water, and there's a few different designs to model.


The shonky approximation I talked about earlier was calculating the lift and drag for each blade for each angle of attack (with every angle of attack having a new Reynolds number too, because of the angular velocity of the turbine adding to the flow velocity), giving a resultant force and direction, which I then distributed over both the 'top' and 'bottom' halves of the blade, pointing in the resultant direction I mentioned. This is obviously a REALLY bad approximation, giving stress directions that are completely wrong, and creating a huge peak in stress near the trailing edge of the foil. I created the parts in Solidworks and then ported them across to AutoDesk Simulation.

SO: long story short, I am looking for a way to calculate the pressure field around an object in flow, and then apply this pressure field in order to then perform a stress analysis on the object. If there is a way to do this in AutoDesk Simulation, or another AutoDesk program that I'm able to get a student trial of, I would LOVE to hear about it! I've had to overhaul my methodology so many times, and at this point, I'm desperate!

 

EDIT: I should say that I'm just looking to perform a static analysis of the blade as a fixed beam (have been using a brick element)- no motion of the turbine is necessary, just the incident flow on the blade.

 

Thanks for any help you're able to give me.

Dylan

 http://upload.wikimedia.org/wikipedia/commons/9/9e/Darrieus.jpg

2 REPLIES 2
Message 2 of 3
S.LI
in reply to: dylanad

Autodesk Simulation could solve this kind of coupling problems.

Pressure calculation from CFD processors, then export it to stress analysis processor to obtain stress/strain in the structure.

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Message 3 of 3
Joey.X
in reply to: S.LI

In Autodesk simulation Multiphysics, do fluid flow analysis with MRF(Multiple Rotating Frame of reference) for this rotating device, notes that this step can get result of reaction force which has contribution from (a) pressure (normal to surfaces), (b) shear stress (tangential to surfaces). 

The second step is doing linear stress analysis, which can apply fluid reaction force in first step as one of the loadings. 

 

Jianhui Xie, Ph.D
Principal Engineer
MFG-Digital Simulation

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