Tutorial how to do a flow simulation to a rotating propeller?
The purpose of this tutorial is to see the trajectories of a fluid, that is moved by a outboard propeller. Usually in flow simulations, we adjust the fluids options (speed pressure etc), but what happens when we want to see how a fluid is pushed by a propeller?? This is how you calculate it...
These are the steps to do a flow analysis...
Answered with a tutorial: https://grabcad.com/tutorials/tutorial-how-to-do-a-flow-simulation-to-a-rotating-propeller
I've just tried this with my http://grabcad.com/library/impeller-ideal-for-cfd-or-3d-print and it worked quite well, is there anyway you could expand the tutorial to add the propeller so that it is inside pipe or housing (such as a pump)?
What is the importance of the rotating region boundary. In this tutorial, it seams pretty close to the blade tip. Is it necessary to do it like this? I try to do it with a turning gear and I'm getting a velocity discontinuity between my rotating region boundary and the free air around it (the rotating region diameter is .25in away from a .5in high tooth for a 4in dia gear). Any idea why? Is it a mesh refinement issue? Thanks for the post anyway, it helped a lot.
I've been trying to search on how to find the RPM of a turbine using solidworks flow sim., given that you know the mass flow rate or volume flow rate. but i did not find any descent or exact tutorial so i gave up and ask my VAR and they said that Flow Simulation does not have this capability but they said that maybe other CFD software can do this, so anyone could recommend a CFD software that can do this. thanks,
Hi, I am new to this forum and found this useful tutorial. It is very useful. I further need to know if turbine impeller is housed in the volute casting how to carryout flow simulation? How to include non rotating parts outside the rotating region, for example casing inside surface, in the simulation?
The rotating region has to engulf only the rotating parts or acn go completely till the inner face of the shell where the propeller is. I mean if you have a tug boat propeller, then you put the rotating region only around the propeller(to contain the propeller?) or will the inner surface of the shroud?
Thanks Andreas- is the only tutorial online so clear and helpful//
Is not by chance that the original developers called the company NIKA
I want to add to my comment: if you have a tugboat propeller- that is a propeller in a cylindrical shell, you have to put the rotating region to c ontain only whatever is rotating there?-that is the propeller? or you can put the rotating region up to the inner surface of the cylindrical shell?
What if the shell has inside some redirecting fins(small that is ) to direct the flow in axial direction, cutting the rotation of the fluid(induced by the propeller)?
Who invented this method of rotating region? is the product of a very clever mind who had a deep insight in the relative motions and meshing(FEA theories)- .
Then , I heard that you have to put in the gap between the propeller and the inner surface 2-3-4v4n 4 cells to be sure all is OK. and having a lot of RAM.
Andreas are you still there? can you help?
Im new at this forum.
Jehan: Define a fluid speed along the Z axis (Negative sign as it is a speed "relative" to the propeller)
Regarding this propeller setup:
The fluid speed is set up to 0m/s. It means that flow motion, thrust and torque are going to be computed for the "static" propeller condition which for most cases is not practical.
For a real analisys, a parametric study would be the way to go.
In quite a rough way the thing would go as follows .............
As first step, an initial guess of the ship service speed, propeller RPM and hull drag must be known.
Then, with fixed RPM, a range of fluid speeds around the required Ship speed, must be studied(-Vz in this model). The goal is to overcome the hull drag, with the minimum required torque.
Take the best result from above and define a new parametric study.
Fix speed of advance (-Vz) and check a range of RPM around the required one.
Once again, Best thrust with less torque is the best choice.
Thust would come from Force[Z] surface goal.
Torque from Torque[Z] surface goal.
Hope this can help.
Because you are solving this problem using a rotating reference frame (RRF) approach, then in Step 2, you should make the cylindrical sketch (representing the RRF) slightly larger than the rotating propeller. The idea here is that you are solving the RRF separately from the global (rectangular) computational domain and the solver needs to transfer information back and forth. Thus having a few (say 2-3) computational cells between the rotating impeller body and the diameter of the rotating RF cylinder is of utmost importance. I also typically recommend to define a volumetric mesh control using the RRF cylinder for these solutions.
If you are performing an internal calculation with a RRF, then best practice is to still extend the RRF body beyond the rotating impeller, even if it goes into the solid housing around it. It's better to bury the RRF body into the way and define any walls that it crosses as Stators (in the Wall boundary condition).
Overall though, a nice tutorial for beginners.