A smart pipe energy harvester excited by fluid flow and base excitation

This paper presents an electromechanical dynamic modelling of the partially smart pipe structure subject to the vibration responses from fluid flow and input base excitation for generating the electrical energy. We believe that this work shows the first attempt to formulate a unified analytical approach of flow-induced vibrational smart pipe energy harvester in application to the smart sensor-based structural health monitoring systems including those to detect flutter instability. The arbitrary topology of the thin electrode segments located at the surface of the circumference region of the smart pipe has been used so that the electric charge cancellation can be avoided. The analytical techniques of the smart pipe conveying fluid with discontinuous piezoelectric segments and proof mass offset, connected with the standard AC–DC circuit interface, have been developed using the extended charge-type Hamiltonian mechanics. The coupled field equations reduced from the Ritz method-based weak form analytical approach have been further developed to formulate the orthonormalised dynamic equations. The reduced equations show combinations of the mechanical system of the elastic pipe and fluid flow, electromechanical system of the piezoelectric component, and electrical system of the circuit interface. The electromechanical multi-mode frequency and time signal waveform response equations have also been formulated to demonstrate the power harvesting behaviours. Initially, the optimal power output due to optimal load resistance without the fluid effect is discussed to compare with previous studies. For potential application, further parametric analytical studies of varying partially piezoelectric pipe segments have been explored to analyse the dynamic stability/instability of the smart pipe energy harvester due to the effect of fluid and input base excitation. Further proof between case studies also includes the effect of variable flow velocity for optimal power output, 3-D frequency response, the dynamic evolution of the smart pipe system based on the absolute velocity-time waveform signals, and DC power output-time waveform signals

Fluid-structure interaction in liquid-filled piping systems

Fluid-structure interaction in liquid-filled piping systems is modelled by extended waterhammer theory for the fluid, and beam theory for the pipes. All basic coupling mechanisms (Poisson, junction and friction coupling) are modelled. Two different solution procedures are presented. In the first procedure the governing set of equations is solved by the method of characteristics (MOC). In the second procedure the fluid equations are solved by the method of characteristics, while the pipe equations are solved by the finite element method in combination with a direct time integration scheme (MOC-FEM). The two procedures are compared with each other for a straight pipe problem. The MOC-FEM procedure is also verified against a solution procedure in which the pipe equations are solved by modal superposition. The mathematical model is validated by simulation of two experiments known fromliterature: a straight pipe experiment and an experiment with one freely moving elbow. A provisional guideline is formulated which states when interaction is of importance