The Fluid-structure Coupling Analysis of Steel-Wire-Reinforced Flexible Pipe Under Inner Fluid Pressure Impact

Identifying dynamic characteristics of the fluid filled steel-wire-reinforced flexible pipe is vital in controlling the pipe vibration. A direct fluid-structure coupling method based on finite element analysis is proposed and validated by modal simulation of an oil filled T-shape pipe. An innovative way of modeling steel-wire-reinforced rubber pipe is put forward. The modeling method is validated by modal test of the water-filled pipe. The 2nd Mooney-Rivlin constitutive model is used for the rubber material. Transient dynamic simulations of a bending steel-wire-reinforced pipe filled with water under step and sine-shape pressure impact are performed for the first time. Different fluid turbulence models are used to evaluate the influences on pipe vibration. The dynamic characteristics of the water filled flexible pipe is researched under different fluid pressures. The vibration peak frequencies of the water-filled pipe under various impact excitations coincide well with the fluid-structure coupling modes of the pipe.

A Simple Method to Design and Analyze Dynamic Vibration Absorber of Pipeline Structure Using Dimensional Analysis

Vibrations due to mechanical excitation and internal and external fluid flow can cause fatigue in pipelines and leaks in fittings. A beam-based dynamic vibration absorber (beam DVA) is a device comprising an L-shaped beam with a concentrated mass at its free end that can be used to absorb and dissipate vibrations in the pipeline. In this paper, a mathematical equation is extracted to design the beam DVA using the dimensional analysis (DA) method and data recorded from 120 experimental tests. In the experimental studies, the pipes are fabricated in 1-inch, 2-inch, and 3-inch sizes. Each pipe is subjected to harmonic excitation at different frequencies, and the amplitude of vibration of the pipe is evaluated by changes in the geometric characteristics of beam DVA and concentrated mass. The proposed methodology is validated using the finite element method and simulation in the SIMULINK/MATLAB. The results showed that, out of the nine effective dimensionless parameters identified in pipe vibration control, mass ratio and stiffness ratio have the highest and lowest impacts on pipe vibration absorption, respectively.

Sweeplus®: An Integrated Solution to Pipe Vibration Failures

This paper discusses our efforts to develop a robust branch fitting that can withstand AIV related to higher sound power levels than a standard contour fitting and accommodate FIV related vibration loads, without compromising project cost and schedule. Numerical simulation results and experimental test data are presented to substantiate our claims that a sweeplus® performs much better than any other contoured branch fittings available in the market with respect to any AIV, AR and FIV related risks. The aerodynamically shaped new fitting can withstand higher sound power level (PWL) limits in AIV, has smoother curvature to reduce flow separation, vortex formation and shedding thereby lowering peak stress concentrations and avoiding AR and FIV related risk, has an extended fatigue life, while adhering to ASME B16.9 Code requirements.

Research on the Impediment to Vibration Wave Propagation of Pipe from a vibration isolation mass

In order to control the pipe vibration, the performance of flexible connection with vibration isolation mass in impeding vibration wave propagation is studied. Based on the principle of impedance mismatching and numerical analysis method, the influences of vibration isolation mass and rotational inertia on the vibration wave propagation in pipe were discussed. The results show that the isolation mass is good at reducing the vibration of wave transmission in intermediate and high frequency domain. Meanwhile, The larger rotational inertia of the isolation mass, the better the damping effect. A useful reference was provided for the application of flexible connection to the vibration isolation and noise reduction of ship pipe.

Numerical Study of Orifice Cavitation-Induced Instability and Pipe Vibration

Different kinds of orifice are widely used as a resistance element to reduce pressure in various piping systems. However, due to strong shear and turbulence mechanisms around the orifice, it is susceptible to instabilities that generate pressure fluctuations and pipe vibrations. Especially when cavitation occurs, this effect can be very strong. The present work tries to characterize orifice-induced instability by means of numerical simulations and assess pipe vibration levels. Firstly, by taking an elongated orifice as an example, the fluctuating pressure around the orifice is obtained by a Large Eddy Simulation with a 2D unsteady model of cavitation. Secondly, the pipe vibration response is studied with experiment. The variation trends of pressure fluctuation and pipe vibration are analysed under different operation conditions. The results of the simulations can provide a good explanation for pipe vibration. A relationship between orifice cavitation-induced instability and vibration is established based on numerical simulations and experimental results.