CFD Online Discussion Forums (http://www.cfd-online.com/Forums/)
-   Main CFD Forum (http://www.cfd-online.com/Forums/main/)
-   -   Two questions concerning flutter? (http://www.cfd-online.com/Forums/main/80971-two-questions-concerning-flutter.html)

 lakeat October 12, 2010 15:03

Two questions concerning flutter?

I have Two questions concerning flutter (external flow),

1. Suppose I have a flat plate parallel to the inflow direction in a wind tunnel, while keeping the wind speed constant at a certain value, what happens if the structure damping is zero? will flutter happen when the structural damping is zero?

2. What is the worst shape of a structure, which is the most unstable and has the lowest flutter point? (Structure, I mean rigid body here)

Any ideas? Thanks,

 Alanseu April 7, 2011 07:15

Quote:
 Originally Posted by lakeat (Post 278866) I have Two questions concerning flutter (external flow), 1. Suppose I have a flat plate parallel to the inflow direction in a wind tunnel, while keeping the wind speed constant at a certain value, what happens if the structure damping is zero? will flutter happen when the structural damping is zero? 2. What is the worst shape of a structure, which is the most unstable and has the lowest flutter point? (Structure, I mean rigid body here) Any ideas? Thanks,
Dear sir:

firstly, regarding to the structure damping is zero, you can refer to the plot of V-g curve, the real/ practical structure is not zero forever, which is a positive unknow values for which is changed as the velocity.
In computational method, we can judge the bundary of flutter velocity is at the point of the damp is zero. which is a conservative value, smaller than the real flutter velocity.

secondly, when the structure is located in the flutter, which notes the structer is in the harmonic motion, when the velocity is a little bigger, or the external energy put on the surface of the structure, the structure will locate in unstable motion.

 lakeat April 7, 2011 09:28