Learning Forum

[seckin]

Hi 

 

I found an underwater modal analysis example of immersed propeller. I followed the instructions from the tutorials.

However i can not get the same according to the academical studies. 

As you know, added water mass should reduce the natural frequencies, but ?n my study nothing happens.

My questions;

1- Tutorial fixed the propeller hub. Is it correct, because i want to simulate underwater free modal?

2- ? tried two studies. first one ? only fixed the hub of propeller and only examine the propeller. the second one i fixed the hub of propeller and add a volume for water then followed instruction from the tutorial. I expected that the reduction of the natural frequencies but nothing changed.

I attached the model at the link below

https://www.dropbox.com/s/5cksnowd4aaytjw/mypropeller.wbpz?dl=0

Could you please examine the model and tell me where i did wrong?

Best Regards and sorry for long post.

[Keyur Kanade]

Hello, 

Can you please let us know which tutorial you are following?

As ANSYS Employee we can not download attachments. So can you please insert images and describe your problem in details. 

Regards,

Keyur

[seckin]

Hi Keyur 

Thanks for your attention.

First picture is ansys tutorial. Second picture is my study. I followed the same commands, but i can not get the correct results.

i tried two studies. first one ? only fixed the hub of propeller and only examine the propeller. the second one i fixed the hub of propeller and add a volume for water then followed instruction from the tutorial. I expected that the reduction of the natural frequencies but nothing changed.

Could you please examine the model and tell me where i did wrong?

 

 

[seckin]

Also, ansys solved the problem with unsymmetric solver. As i understand the model is correct , because the unsymmetric solver only solves the acoustic problem.

Then i changed the density of water and speed of sound and the natural frequencies still the same.

Thanks again

[Keyur Kanade]

Hi, 

You are using mechanical. I am from fluids background. So moving this thread to Structural Mechanics category for better response. 

 

Regards,

Keyur

[seckin]

Hi Keyur 

 

Do you know any alternative way to do underwater modal analysis? Maybe using flow simulation?

 

Regards

Seckin