Centrifugal force on rotating blades

[wisemo]

Hi everyone,

I've got a set of airfoil blades here which are homogenious and have a constant profile (x-section). Each blade is of equal length (as should be).
What would the best way be to calculate the centrifugal force on the blade root as a result of constant angular speed? say o - rads/s

I've just gotten a little confused about involving the 'centre of gyration'.

thanks

mo

 

[LURCH]

If you can calculate the average force throughout the blade, and multiply by the length of the blade, that will give you the total force, all of which is felt at the root of the blade.

 

[Graviman]

Easy, since blade is constant section, estimate the centre of mass position and treat the root forces/stresses as if the mass was concentrated at the mass centre - ie CF = Mass.Omega^2.Radius.

 

[ntn]

I have recently came across a test - "Maximum regulating test" with a limit of +/- 15000 kilo-pound been performed on axial fans. Can anyone explain me what this test is all about & how it is performed.
Thanks in advance.

 

[PJC01]

Hello,

The centrifugal force on rotating blades is a result of the angular velocity of the blades and the mass distribution along their length. The blades experience a force away from the center of rotation, which is known as the centrifugal force. This force is dependent on the angular velocity (ω) and the distance from the center of rotation (r).

To calculate the centrifugal force on the blade root, you will need to use the equation F = mω^2r, where F is the centrifugal force, m is the mass of the blade, ω is the angular velocity, and r is the distance from the center of rotation. The center of gyration is a point that represents the distribution of mass along the length of the blade. It is used to simplify calculations and determine the effective radius of rotation.

To calculate the center of gyration, you can use the equation k = √(I/m), where k is the distance from the center of rotation to the center of gyration, I is the moment of inertia, and m is the mass of the blade. Once you have determined the center of gyration, you can use it in the centrifugal force equation instead of the distance from the center of rotation (r).

I hope this helps clarify the concept of centrifugal force on rotating blades. Let me know if you have any further questions. Thank you.