Hydrodynamic performance analysis of flapping hydrofoil for single-body architecture wave glider

Abstract

Wave energy is directly converted into the propulsion of wave gliders by using the flapping hydrofoils. The propulsive performance of the wave glider has relationships with some parameters, especially spring constant of the submerged flapping hydrofoil mechanism and wave frequency. A numerical model of the submerged passive flapping hydrofoil based on the float response of the single-body architecture wave glider was established to analyze its propulsion in this paper. The float response was analyzed by using Advanced Quantitative Wave Analysis (AQWA) software under different wave frequencies in time domain and frequency domain. The numerical model of the hydrofoil was established, and the forward speed under different wave frequencies and spring constants were analyzed by using ANSYS-FLUENT software. By means of the polynomial curve fit, the corresponding equation describing the response of average forward speed was established. Tank experiment and sea trial were carried out to verify the accuracy of the model and the propulsive performance of the single-body architecture wave glider. The results showed that the speed fluctuation of the flapping hydrofoil was smaller as wave frequency increased under four wave frequencies. At the same time, wave frequency had a close relationship with spring constant, and there was an optimal spring constant under different wave frequencies to maximize the navigation speed of the whole system.