Good evening
As part of a TIPE, I modeled a counter-rotating propeller on Solidworks and then simulated its operation with Meca3D . However, I would need to know the thrust that the one can generate when it turns in the water. The problem is that I have no idea how to do this (what efforts, etc...).
Could someone help me?
Thank you in advance.
PJ: a screenshot of my modeling on meca3D.
Hello @quentinprt
Solidworks for its CAD part will be of no use to you apart from the modeling you have already done. They are boat propellers because on an airplane there is no chance that it will work given the 3D CAD.
At best you would need the FlowSimulation module which is not a freeware but a "trestréscherware" and whose implementation is quite, to very difficult: for those who do not master the simulation. The level of knowledge acquired in Terminal and a little beyond is certainly not enough to achieve your goals because the calculations on the propellers are hyper-complex and even worse for the counter-rotating ones (cf the A400M).
All is not lost though ;-) I suggest you look at the HELICIEL software which is a specialized software on your subject (also mecaflux)
Good luck and I hope that your TIPE will satisfy everyone and especially you first ;-) ;-)
Kind regards
PS: to show you the magnitude of the task I suggest you read this topic which will surely give you good information.
https://www.lynkoa.com/forum/solidworks/mod%C3%A9lisation-dune-h%C3%A9lice-davion
Hello
Thank you for this answer. In this case, I'm going to look at the software you told me about and I'll try to see if my institution doesn't have FlowSimulation (who knows...).
Thank you again.
Kind regards.
Hello
After checking I was able to see that my establishment has Flow Simulation, so I started to get to grips with it.
Now I would like to know how to get the thrust generated by my propeller? (I saw that you can tell the software different objectives (global, surface...) so which "objectives" should you ask the software and where to apply them?)
Thank you for your answers.
Quentin
Good evening
Flow simulation is a complex software and in my experience cannot be controlled with a snap of the finger or a power of will.
In addition, you attack the cliff without experience or skills acquired in general in engineering school
If you think carefully you will see that you are not in the case where it is the fluid that is in motion (like the air that enters and leaves an electronic box to cool it).
In your case it is the movement of the propeller that moves the fluid (water in this case).
To help you a little bit check out this
Kind regards
Good evening
In reality I have read that the displacement of the propeller in the water will be equivalent (probably to simplify) to the displacement of the water in a fixed propeller.
I could see that to calculate the thrust with Flow simulation, it would be enough to choose a surface objective by selecting all the blades and choosing the Force according to the direction of the flow (flow to which I would have given the speed at which my propeller moves here 40kn (~20m/s)).
Do you think this method can also be used for a counter-rotating propeller?
Unfortunately I don't have the possibility to fully master the software, so I am forced to only find out what could be useful to me (I have already figured out how to put my propeller in rotation and start the calculation of the streamlines). However, my final objective would simply be to check with flow simulation the "theoretical" results, then to vary the parameters of my propeller to observe their influence on the thrust.
Kind regards
Hello
My research has progressed a little and I have managed (with the method presented in my last message) to obtain rather consistent thrust values. However, something is bothering me:
Indeed, when I observe the streamlines on flow simulation, I notice that the water is slowed down at the exit of my counter-rotating propeller, yet the rotation speed is that of the real model.
Is this normal?
Attached is a photo of the phenomenon.
Thank you
Hello
This is normal to some extent for the following reasons
Contrary to popular belief, the speed of the flow does not increase in speed, unlike the reactor.
(Source wikipedia) The advantages of counter-rotating propellers include the ability to recover some of the rotational energy lost by the forward propeller, resulting in better overall efficiency; the ability to use a lower rotational speed for the same diameter than with a conventional propeller (or the same rotational speed for a smaller diameter); Lower blade load, resulting in reduced cavitation and associated noise.
Read more on Wiki
Kind regards
For the record, if you put a propeller of too large a diameter and a very powerful engine, well it's the boat that rotates around the propeller (real case) which doesn't happen with a counter-rotating (look at what is said about torpedoes. ;-) It is for this reason that the powerful outboards have two engines at the rear and the large inboards have two propellers with two shafts spaced apart.
Super! Thank you very much for that answer.
Kind regards.
Good evening
I did a simulation with a single propeller rotating on Flow simulation and I still observe that the liquid is slowed down at the exit of the propeller. Where could this come from?
(The rotation speed is 1280rpm or 134rd/s)
(The water arrives in the propeller at a speed of 40kn or 20.57m/s)
Thank you.