Abstract
An application of electromagnetic devices of the motional type (i.e. eddy-current dampers) to improve the dynamic stability of a cantilever pipe discharging fluid is proposed. When the flow velocity reaches a critical value, this system loses stability through the flutter. A contactless damping device is used. This actuator is made of a conducting plate attached to the pipe that moves together with it within the perpendicular magnetic field that is generated by the controlled electromagnets. During the motion the eddy currents in the plate and a resultant drag force of a viscous character are generated. First, an optimal control problem that aims to stabilise the system with the optimal rate of decrease of the system’s energy is posed and solved. Then a state-feedback parametrization of the obtained optimal control, which can be used in a closed-loop scheme is proposed. The effectiveness of the designed optimal controller is validated by making a comparison with the corresponding passive solutions on the specially designed and constructed experimental test stand of a pipe conveying air.
Highlights
The dynamics of pipes with flow have been studied intensively for over half a century [1]
The flow velocity, masses of the fluid, the pipe and the actuators, and the length of the pipe should be such that the system exhibits periodic planar oscillations that could be captured by linear model (1), and the external damping stabilizes the system
This paper has investigated the application of eddycurrent dampers to improve the stability of the cantilever pipe discharging fluid
Summary
The dynamics of pipes with flow have been studied intensively for over half a century [1]. When the flow velocity inside the cantilever pipe exceeds the so-called critical value, self-excited flutter vibrations arise. This behavior is specific to cantilever pipes; that is, pipes which are supported at both ends are prone to a buckling type of instability [5]. When a strong stream of water flows inside a garden hose, its free end makes a snake-like motion on the grass. These kind of systems are prone to changes of their physical parameters and to the introduction of new effects. The destabilizing effect of damping has attracted attention of the researchers, due to its positive impact on devices used for energy harvesting [10]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
