Effect of hydrofoil leading edge waviness on hydrodynamic performance and flow noise

This paper provides a numerical investigation into the effect of the wavy leading edge on the flow structures and noise of a hydrofoil. NACA0012 hydrofoils with straight and wavy leading edges (denoted by SLE and WLE, respectively) are simulated. The simulations are performed using the large eddy simulation approach to obtain the near-field unsteady flow properties and the Ffowcs Williams–Hawkings equation to predict far-field noise. The numerical results at Reynolds number of 2.5×10⁵ show that the fluctuating amplitude of the lift and drag coefficient decreases after the wavy structure is applied to the leading edge, and the flow field around the hydrofoil is changed due to the streamwise vortices generated in each trough by the pressure gradient of the leading edge. In addition, the wavy leading edge can effectively reduce or even eliminate the tonal noise of the foil without significantly changing the noise directivity. Moreover, the effect of inlet velocities on noise reduction is studied with three different velocities(1, 2.5, and 4.8 m/s). It is found that at the higher velocity of the three, the WLE has a better inhibition effect on lift fluctuation and a better noise reduction effect.