Propeller Thrust Method

Aidan.B · October 20, 2015, 22:19

Hi All,
I'm attempting to calculate the thrust generated by an RC aircraft propeller and I'm wondering about my method.
I made a small cylinder around the propeller shape and subtracted it. I then made a second cylinder the exact same size, and a larger cylinder and subtracted the smalle from the large to give me two domains, the outer domain and inner domain with cylinder cut out. In CFX I set an interface between the two, input, output and walls on the larger cylinder and set the propeller shaped cut out to be a wall. I've then rotated the inner domain. My trouble is that this rotated the air within the domain, as well as the propeller walls. Is there a way that I can make the air continue its expected path until acted upon by the propeller? Have I gone about this in the wrong way.

I have looked through the rotor-stator tutorial, but as I understand, the whole stator will be rotating along with the blades, so, it doesn't quite match my problem.

Thanks in advance!

-Maxim- · October 21, 2015, 03:40

can you please post pictures of your settings? How did you set up your inner domain?
I would make the inner domain smaller - basically only around the propeller.
Did you use Stage interface or Frozen Rotor?

ghorrocks · October 21, 2015, 06:49

Quote:

My trouble is that this rotated the air within the domain, as well as the propeller walls.

This is a FAQ: http://www.cfd-online.com/Wiki/Ansys...f_reference.3F

It is all good, you are just not viewing it as you expect.

Aidan.B · October 21, 2015, 18:40

Maxim,

I've used Frozen Rotor.

I've attached the inner domain settings. The domain has a wall as the propeller, and an interface around the outside.

My force calculations on the propeller give a result in the range of 0.001 N, where I'm expecting 1-10 N. Would my method be close to what I require, or should I be using an immersed solid?

Thanks ghorrocks, that is much more like I expected.

October 20, 2015, 22:19	Propeller Thrust Method	#1
Aidan.B New Member Aidan Bryant Join Date: Mar 2015 Posts: 2 Rep Power: 0	Hi All, I'm attempting to calculate the thrust generated by an RC aircraft propeller and I'm wondering about my method. I made a small cylinder around the propeller shape and subtracted it. I then made a second cylinder the exact same size, and a larger cylinder and subtracted the smalle from the large to give me two domains, the outer domain and inner domain with cylinder cut out. In CFX I set an interface between the two, input, output and walls on the larger cylinder and set the propeller shaped cut out to be a wall. I've then rotated the inner domain. My trouble is that this rotated the air within the domain, as well as the propeller walls. Is there a way that I can make the air continue its expected path until acted upon by the propeller? Have I gone about this in the wrong way. I have looked through the rotor-stator tutorial, but as I understand, the whole stator will be rotating along with the blades, so, it doesn't quite match my problem. Thanks in advance!

Thread Tools	Search this Thread
Show Printable Version Email this Page	Search this Thread: Advanced Search
Display Modes
Linear Mode Switch to Hybrid Mode Switch to Threaded Mode

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
Underwater Propeller CFD analysis with Ansys CFX	Alaeddine	CFX	7	March 30, 2018 01:37
The problem of unsteady state calculation of propeller static thrust.	liulangdefeng2222	FLUENT	11	July 7, 2015 11:17
Propeller Thrust	mahdisajjadi	FLUENT	1	December 1, 2014 20:24
Turbulence inflow generation - recycling method	panda60	OpenFOAM Running, Solving & CFD	15	April 25, 2013 01:34
Fluent 6.3.26 vs 12.1 and partition method	Anorky	FLUENT	0	April 27, 2010 10:55

October 21, 2015, 03:40		#2
-Maxim- Senior Member Maxim Join Date: Aug 2015 Location: Germany Posts: 413 Rep Power: 13	can you please post pictures of your settings? How did you set up your inner domain? I would make the inner domain smaller - basically only around the propeller. Did you use Stage interface or Frozen Rotor?

October 21, 2015, 18:40		#4
Aidan.B New Member Aidan Bryant Join Date: Mar 2015 Posts: 2 Rep Power: 0	Maxim, I've used Frozen Rotor. I've attached the inner domain settings. The domain has a wall as the propeller, and an interface around the outside. My force calculations on the propeller give a result in the range of 0.001 N, where I'm expecting 1-10 N. Would my method be close to what I require, or should I be using an immersed solid? Thanks ghorrocks, that is much more like I expected.