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Experimental study on vibration of a rotating pipe in still water and in flow

100%

Geng X. , Wu W. , Liu E. , Lin Y. , Chen W. , Rheem C.-K.

2023

tom nr 1

65--77

To illustrate the vibration characteristics of a rotating pipe in flow, experiments were conducted for a pipe in flow, a rotating pipe in still water and a rotating pipe in flow. For the pipe in flow without rotation, the trajectory diagram is ‘8’ shaped. For the rotating pipe in still water, a multiple frequency component was induced, and a ‘positive direction whirl’ was found. For the flow and rotation, at a flow velocity of 0.46 m/s, the vibration is dominated by the combination of flow and rotation. With an increase in rotating frequency, the trajectory of the rotating pipe varies from an ‘8’ shape to a circular shape and the ‘reverse direction whirl’ is induced, which is different from ‘positive direction’ in still water. The vibration frequency ratio increases uniformly with flow velocity. At a flow velocity of 1.02 m/s, at which the frequency is close to the theoretical natural frequency, the vibration frequency ratio is f*≈1. Predominantly governed by vortex-induced vibration (VIV), the vibration behavior of a rotating pipe subjected to fluid flow conditions has been found to exhibit complete vanishing of whirl. The vibration characteristics of a rotating pipe in flow are studied by the experiments which is benefit for structural drilling design.

Minimization of critical flow velocity of aeroelastic energy harvester via delayed feedback control

86%

Sarbinowski F. , Starosta R.

2020

tom Vol. 31, nr 2

art. no. 2020225

The paper describes the procedure of modelling and optimization of the aeroelastic energy harvester from the point of view of their operation at very low flow velocities. Using analytical solutions of models of different device variants, the relationships between their efficiency and flow velocity were presented. By way of analytical considerations, the conditions for high performance operation of the device have been demonstrated, indicating at the same time the difficulty in maintaining it at low operation velocities. As a solution to the problem, the application of external delayed feedback control was proposed and its effectiveness was demonstrated.

Investigation of the Effects of the Incident Flow Angle on Vibration Behavior in Heat Exchanger Tube Bundle

58%

Usman M. , Khushnood S. , Nizam L. A. , Tanveer W. , Shafi A. , Ayub M. , Khan H. F. , Rustam B.

tom Vol. 13, no 2

186--194

An experimental study on the incident flow angle effects on the vibration behavior was carried out on aluminum tube in parallel triangular tube bundle with P/D ratio of 1.375. Fluid elastic instability is the most fatal mechanism from all the vibration mechanisms and therefore must be dealt with a lot of attention. Experiments were performed on low speed water tunnel with the velocity of water ranges from 0.3 m/s to 0.7 m/s. The experiments were designed in a unique way to study the effects of incident flow angle on the vibration behavior. The monitored tube was mounted flexibly in an array of rigid tubes. The experiments were conducted on a flexible tube for different velocities ranging from 0.3 m/s to 0.7 m/s with different array rotated angles (0 to 90 degrees). It was observed that the vibration level was significantly high at 75 degree configuration as compared to other rotated angle configurations. It was also observed that the damping response is dispersed with all positive values, indicating that there is no instability in the tube.