Vibration And Stability Of Pipes Conveying Fluid Under Follower Force

More and more fluid-structure interaction problems are put forward in all kindsof engineering field. The flow-induced vibration of the pipe conveying fluid is paidmuch attention，because it is used as a typical transport system in engineering.Fluid-structure interactions of pipes conveying fluid are studied theoretically andnumerically. The influence of different factors and parameters on their dynamicbehaviors of pipes conveying fluid with different supports is investigated. The focus ison the behaviors of pipes conveying fluid under distributed follower force and endfollower force in vibration and instability. The contents are as follows:1. With Pflüger column model and that of a fluid-conveying pipe, the dynamicbehaviors of pipes with different supports under co-action of flowing fluid andfollower force are considered.2. The differential equations of motion of pipes conveying fluid under distributedfollower force or end follower force are established. The dimensionless differentialequations of motion are established via dimensionless method.3. Curves of critical velocity changing with follower force and mass ratio whenthe system gets unstable are obtained via eigenvalues. System stability region changewith different parameters of critical value can be analyzed via the curves.4. Complex frequencies with different parameters (fluid velocity、 followerforce、mass ratio) are obtained. The effects of the mass ratio, follower force andvelocity of flow on the dynamic behaviors of pipes with different supports areanalyzed.5. The free pipe gets unstable mainly via the third mode and fourth mode. Thepipes under other supports get unstable via the first three modes.Conclusions can be drawn from the numerical results and analyses：stabilities ofpipes conveying fluid with different supports (free-free form, free-support form andsupport-support form) under follower force have great differences. Dynamic behaviors are similar to those under the effects of distributed follower force and endfollower force.