Would you please help me how I can determine natural frequency of pipe conveying fluid?

Would you please help me how I can determine natural frequency of pipe conveying fluid?

Has me curious about the application too. Standing waves set up by sudden valve closure ie. water hammer could be an interesting simulation, if not impossible due to nonlinearities. Damping aside, I suppose knowing the mode list and the standing wave's frequency one could determine if the water hammer is dangerous or not. Simulating damping well is a black art and its mis application has lead to many false conclusions.

Dear Kevin,

Thanks.I want to find natural frequency effect with considring damming of fluid in 1st step then structural damping in 2nd step.In software if use first flowworks simulation then use result for frequency analysis ,but these results is no effect in narural frequency result?!!!

How can we do these analysis with fluid damping and structural damping? if we use composite ,then how can we use fluid effect on composite for natural frequency?

Dear Jerry,

Thanks.I want to find natural frequency effect with considring damming of fluid in 1st step then structural damping in 2nd step.In software if use first flowworks simulation then use result for frequency analysis ,but these results is no effect in narural frequency result?!!!

How can we do these analysis with fluid damping and structural damping? if we use composite ,then how can we use fluid effect on composite for natural frequency?

Banad,

Are you trying to find the natural frequency of the pipe in bending? As a first pass approximation, I would just calculate the weight of the pipe and of the fluid per unit length, then calculate the natural frequency of the pipe using a density that give you the same weight per unit length as the pipe plus the fluid. I wouldn't expect that to be too far off.

Jerry S.