On the investigation of ash deposition effect on flow-induced vibration energy harvesting

This paper proposes harnessing the aerokinetic energy in flue systems and it explores the ash deposition effect on flow-induced vibration energy harvesting performance. Bell-shaped and horn-like bluff bodies are designed to simulate different ash depositions on a conventional elliptic cylinder bluff body. Wind tunnel experiments were conducted to investigate the energy harvesting performance using different ash depositions distributed over the bluff bodies. The experimental results show that compared to the baseline model of a conventional elliptic cylinder bluff body, the bell-shaped bluff body suppresses the flow-induced vibration and deteriorates the energy harvesting performance. In contrast, the horn-like bluff body can benefit energy harvesting by reducing the galloping cut-in wind speed and increasing the voltage output. The voltage output of an optimal prototype using the horn-like bluff body is increased by 516%. Computational fluid dynamics (CFD) simulations were carried out to unveil the physical mechanisms behind the phenomena. The CFD analysis results indicate that the appearance of the small-scale secondary vortices (SV) widens the wake flow and increases the aerodynamic force produced by the horn-like bluff body. The flow-induced vibration of the harvester using the horn-like bluff body transforms from VIV to galloping. Therefore, it has been preliminarily demonstrated that the unfavorable ash deposition phenomenon in flue systems has the potential for promoting flow-induced vibration energy harvesting.