Coupled Hydro-Aero-Turbo Dynamics of Liquid-Tank System for Wave Energy Harvesting: Numerical Modellings and Scaled Prototype Tests

Abstract

An integrated numerical model is proposed to explore the coupled hydro-aero-turbo dynamics of a novel wave-energy-harvesting (WEH) liquid tank. A scaled prototype of the WEH liquid tank with an impulse air turbine system is made to experimentally validate the numerical model. Multi-layered impulse air turbine systems (MLATS) are creatively introduced into the liquid-tank system. The inherent mechanisms of the coupled hydro-aero-turbo dynamics of the WEH liquid tank with different turbine properties are systematically investigated. The optimal power take-off damping for the WEH liquid tank is identified. Improving Turbine-L1 to Turbine-L2 or Turbine-L3 can increase the averaged power output by about 25% or 40%, respectively. Increasing the tank breadth can effectively boost the power output in a nonlinear way. Under the considered excitation conditions, if the tank breadth is doubled, the maximum averaged power output can be increased by around four times. Through a series of failure tests, Turbine-L3 shows greater reliability in extreme conditions compared to a conventional single-rotor turbine. Even if the most important rotor of Turbine-L3 fails to work, the maximum loss of the averaged power output is only 44%. The present WEH liquid tank with Turbine-L3 shows improved efficiency and reliability.

Keywords: wave energy, liquid sloshing, Wave energy converter, power take-off