[cvcdcvcd]

hello
I just wanted to do a cfd analysis on helicopter blade
the case is 2-d with usual movements of the helicopter, the blades are rotating with velocity omega, also moving forward with advance velocity and some pitching movement for each blade is assumed to exist.
my question now is, for the moving grid of above:
1-which software package is the best for modeling and solving?
2-how hard the job is using that software package?
3-sholud I write any code with that software package?
the project is solved assuming viscous flow, so turbulence modelling is another aspect.
isn't it better at all to write a code manually?
is open foam capable of this?
thanks everyone

[fluid23]

When you say 2-D, are you (1) implying that you are analyzing the airfoil at a particular span location with flow conditions that vary with time representative of the cyclic motion of the rotor? Or... are you (2) saying that you want to analyze the rotor using quasi-2D method (something like blade element momentum method)?

If the answer is (1), then just about any code should handle that analysis. Each has it's own learning curve and the term 'hard' is highly subjective. No user code should be required, but you will need boundary conditions setup to vary with time to match whatever your flow condition should be.

If the answer is (2), then I would recommend star-ccm. It has a tool called virtual disk with an option for blade element method that allows you to specify the geometry and the aerodynamic characteristics of the rotor in the context of other CFD analyses. For example, you could use this to approximate the effect of a propeller in front of a wing or use a series of them to predict the flow field in a wind farm. Now if you are looking for tip vorticies or other higher level effects this will not work, but it is a good baseline estimate of rotor performance.

[GorkemAtay]

What a wonderful answer this is! Not only the content but also the order.

[cvcdcvcd]

hello again
thanks so much MBdonCFD
I have to handle case 1:
a 2d airfoil which is pitching, plunging, and variational free stream velocity, typically sinusoidal free stream velocity
my case is a helicopter blade, airfoil extracted at a particular span from hub, but similar cases of pitching and plunging airfoil are in turbine blades, for example
which software can do that for me the best? and good future, as I am newbie and I am going to learn a cfd soft and live with it!
openfoam? fluent? cfx?
thanks in advance so much

[fluid23]

If you are a newbie, I would avoid openfoam. From what I understand it has a higher learning curve than most other software. Fluent/CFX I am sure would do the job. I am personally partial to star-ccm+. It is a fairly easy to use and robust package.

[cvcdcvcd]

thanks so much
I think you are right
I have to do more research and then decide
by the way, star ccm is another soft which can do the job, if whatever written in its brochure is true!

[cvcdcvcd]

hello everybody again!
after some discussion with my instructor, I arrived to the conclusion that I must use overset grid. to explain more, for the accuracy of the results, I must employ two grids. there is one background grid fixed and another grid, which encircles the airfoil and moves with it, the motions of pitching and variational free stream must be applied to this grid, too.
after some research I found that dynamic mesh in fluent makes or generates the new grid, not moving it, but my instructor says that newly generated grid by fluent may not provide enough accuracy, as we need.
I used fluent 6 user manual, does any body know that in recent versions of fluent overset grid has been added or not?
what other soft wares can one suggest, providing overset moving grid as I need for my case? there must be one fixed grid and one moving grid over that.
thanks so much

[adrin]

If you are in the U.S. (I forget if you have to be a U.S. citizen) then NASA's OVERFLOW code is both open source and is overset-grid-based. It is used for rotor blade flow simulation often.

adrin