TRANSVERSE VIBRATIONS OF TENSIONED PIPES CONVEYING FLUID WITH TIME-DEPENDENT VELOCITY

✍ Scribed by HALIL RIDVAN ÖZ; HAKAN BOYACI

• Publisher: Elsevier Science
• Year: 2000
• Tongue: English
• Weight: 344 KB
• Volume: 236
• Category: Article
• ISSN: 0022-460X
• DOI: 10.1006/jsvi.2000.2985

✦ Synopsis

In this study, the transverse vibrations of highly tensioned pipes with vanishing #exural sti!ness and conveying #uid with time-dependent velocity are investigated. Two di!erent cases, the pipes with "xed}"xed end and "xed}sliding end conditions are considered. The time-dependent velocity is assumed to be a harmonic function about a mean velocity. These systems experience a Coriolis acceleration component which renders such systems gyroscopic. The equation of motion is derived using Hamilton's principle and solved analytically by direct application of the method of multiple scales (a perturbation technique). The natural frequencies are found. Increasing the ratio of #uid mass to the total mass per unit length increases the natural frequencies. The principal parametric resonance cases are investigated in detail. Stability boundaries are determined analytically. It is found that instabilities occur when the frequency of velocity #uctuations is close to two times the natural frequency of the constant velocity system. When the velocity #uctuation frequency is close to zero, no instabilities are detected up to the "rst order of perturbation. Numerical results are presented for the "rst two modes.

2000 Academic Press