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Lift effect and Centrifugal Pressure

Hello everyone

 

Me again,

 

Actually I'm working on a mixer blade and I have to study it's behavior under different loads (centrifugal, vibration etc.).

 

The blade has a shape like an aircraft wing, and when it turns at high speed (~ 15.000 rev/min), we can consider that the lift/drag effect appears and the pressure difference between the upper and the lower surfaces creates a motion and some parts are fixed, so a stress appears. And this takes place in water (density 1000 kg/m^3, more if you consider mixing fruits, vegetables ...)

 

I tried to do a flow simulation to determinate the pressure on upper/lower surfaces but I don't have the licence for it.

I found that there is a load called " Centrifugal Pressure" where you can specify density, rotary speed, center of rotation ... but I don't know if that load is what I need to simulate the lift effect. 

 

Can you tell me more about this load ? And for the lift effect what should I use ?

 

Thank you.

 

Arthus

2 REPLIES

Re: Lift effect and Centrifugal Pressure

Dear Arthus,

"Centrifugal Pressure" is a radially-varying centrifugal pressure load that is applied to the surface of a solid geometry, where the software calculates centrifugal pressure as the sum of the static pressure and the pressure due to rotation.

The CENTRIFUGAL PRESSURE command is intended to account for the load effect of the fluid at the walls of the rotating tank surface, please do not get confused with ROTATION command that creates a body load that acts in the whole structure body. The Rotation command should be used to model rotation loads. Rotation loads are the inertial forces that result from the angular motion of a body about a fixed axis under angular velocity and angular acceleration.

Then in your case if you need to account for drag & lifting forces the only way to get these results is to run a CFD analysis using NX FLOW.

Best regards,
Blas.

Blas Molero Hidalgo, Ingeniero Industrial, Director
IBERISA • 48004 BILBAO (SPAIN)
WEB: http://www.iberisa.com
Blog Femap-NX Nastran: http://iberisa.wordpress.com/

Re: Lift effect and Centrifugal Pressure

Hi Blas,

Thank you for your answer.

 

If I'm understanding right, the CENTRIFUGAL PRESSURE creates a load on surfaces which are in contact with a fluid, correct ? So, if that is correct, it can be applied to my study because the surfaces of the blade rotate and they are in contact with water.

But this load does not take into account the lift effect.

And what is the physical origin of this load ?

 

Thanks, 

 

Arthus