A new concept of hydrokinetic turbine using dual oscillating hydrofoils to extract energy from water currents(tidal or gravitational) was presented,which is particularly well suited for riverbeds and shallow waters near the coasts due to its rectangular extraction plane.The corresponding mathematical model and mesh model were established.A domain dynamic mesh strategy was used on fluid domain within sliding interface to make it move with the airfoil.The software Fluent was used to solve the turbulent flow around the airfoil.The influence of the reduced frequency,pitching amplitude and Reynolds number on the NACA0015 oscillating airfoil in aerodynamic characteristics and energy extraction performance was studied in the paper.Results showed that the reduced frequency,pitching amplitude and Reynolds number could influence boundary layer separation and vortex structure around the hydrofoils,affecting lift characteristics,drag characteristics,pitching characteristics and energy extraction performance.Reduced frequency and pitching amplitude had a greater influence on the time averaged power coefficient and energy extraction performance.With the reduced frequency of 0.14,pitching amplitude of 75° and Reynolds number of 5×105, the hydrodynamic and energy extraction performance could be better.The efficiency of energy extraction could reach 40%.
