Flow-induced vibration of twin-pipe model with varying mass and damping: A study using virtual physical framework

TL;DR

This study uses a virtual physical framework to systematically analyze flow-induced vibrations in twin-pipe models, revealing how mass ratio and damping influence their dynamic responses and hydrodynamic interactions.

Contribution

It introduces a flexible virtual physical testing approach to explore FIV in twin-pipes, highlighting the effects of mass ratio and damping on their vibrational behavior and hydrodynamic features.

Findings

In-line hydrodynamic interaction increases with mass ratio.

Torsional moment coefficient stabilizes around 0.46 at low mass ratios.

Resonance behavior persists at mass ratio 1.0.

Abstract

Flow-induced vibration (FIV) commonly occurs in rigidly coupled twin-pipe structures. However, the limited understanding of their FIV responses and hydrodynamic features presents a major challenge to the development of reliable engineering designs. To bridge this gap, the present study systematically investigates the FIV characteristics of a rigidly coupled twin-pipe model with elastic support using a virtual physical framework (VPF), which enables flexible control of structural parameters during physical testing. A distinctive feature of twin-pipe structures is the presence of in-line hydrodynamic interactions and torsional moments arising from the rigid coupling. The in-line interaction is primarily compressive and becomes more pronounced as the mass ratio increases. The torsional moment coefficient exhibits a rise-fall trend with increasing reduced velocity $U_R$ and stabilizes around 0.46 at low mass ratios. In addition, an "amplitude drop" phenomenon is observed at $U_R=6$, attributed to energy dissipation from the downstream pipe. The mass ratio significantly affects FIV amplitude, frequency, and hydrodynamic coefficients. As the mass ratio decreases, the synchronization region broadens and the hydrodynamic coefficients become more stable. At mass ratio of 1.0, a "resonance forever" behavior is observed. Damping primarily suppresses FIV amplitude, with minimal impact on dominant frequency and hydrodynamic coefficients. These findings provide valuable insights into twin-pipe FIV mechanisms and support a scientific basis for future structural design optimization.