振荡翼改进运动模型的能量捕获性能分析

为了提高振荡水翼的水动力性能和能量捕获效率,基于传统简谐运动模型提出改进运动模型,通过引入俯仰运动系数k,推导改进后俯仰运动规律的一般形式,利用Fluent软件建立水翼的二维模型,综合分析半主动振荡模型下不同俯仰运动系数、折算频率和俯仰振幅等运动参数对水翼能量捕获性能的影响。结果表明:与传统简谐运动模型相比,改进运动模型能够使水翼升力系数在较长时间段内维持较大数值,提高水翼的升力系数和捕能效率;在相同的折算频率和俯仰振幅下,减小俯仰运动系数会增大俯仰角转动的角速度,进而增大俯仰运动所消耗的能量;不同俯仰振幅下对应不同的最优折算频率,折算频率越低水翼的捕能性能越不稳定,俯仰振幅越大,转动俯仰角所消耗的能量越多。在给定参数条件下,水翼的能量转化效率可超过40%。

Energy harvesting performance analysis on improved motion model of oscillating hydrofoil

In order to improve the hydrodynamic performance and energy harvesting efficiency of the oscillating hydrofoil, an improved motion model was proposed based on the traditional simple harmonic motion model. By introducing the pitch motion coefficient k, the general form of the improved pitch motion law was deduced. The two-dimensional model of the hydrofoil was established using Fluent software, and we further analyzed the effects of different pitch motion coefficients, motion frequency and pitch amplitude on the hydrofoil energy capture performance under the semi-active oscillation model. The results showed that, when compared with the traditional simple harmonic motion model, the improved motion model could make the lift coefficient of hydrofoil maintain a larger value for a longer period of time, meanwhile the lift coefficient and energy capture efficiency of the hydrofoil also were improved. Under the same value of reduced frequency and pitch amplitude, reducing the pitch motion coefficient could increase the angular velocity of the pitch angle rotation, thereby increasing the energy consumed by the pitch motion. Different pitch amplitude corresponded to different optimal reduced frequencies. The lower the reduced frequency, the more unstable energy-capturing performance of the hydrofoil, the greater the pitch amplitude, and the more energy consumed for turning the pitch angle. Under the given parameters, the energy conversion efficiency of the hydrofoil could exceed 40%.