Airfoil Design And Performance Analysis On Bi-directional Horizontal Axis Tidal Turbine

As a research heat on new renewable energy field, tidal current energy owns the characteristics of greater energy density, lower noise as well as more easily to predict etc. However, current tidal turbines are more likely performed only under one direction, which can cause energy wasting. Hence, considering about actual conditions about tidal turbines’ utilization, to develop bi-directional tidal turbines is urgently needed, while design on reversible airfoils has become the key to success. With the foundation of traditional lowspeed airfoils, comparison of influences on airfoil performance has been done under various geometric factors, which has given two excellent airfoils with different cambers. Reversejointed method has been applied to reversible airfoils design, while hydrodynamic performance has been also studied. Aiming at testing feasibility of reversible airfoils’ design method, bi-directional tidal turbines have been designed based on reversible airfoils mentioned above.(1) Research on method of 2D numerical simulation of airfoil flows have been conducted, while option mode of every step in simulation process has been also checked. Example validation of NACA4412 has proved accuracy of numerical simulation method. This method has been used to simulate 4 groups’ airfoils of different geometric factors, which resulted in influences on airfoil performance caused by such factors.(2) Based on consequences gained above, two excellent airfoils have been chosen as the original model. Using intercepting the different chord length on original model of reversejointed method to get new reversible airfoils, then numerical simulation has been conducted under the design condition of tidal turbines. The results has revealed that although hydrodynamic performance become decreased, due to its bi-directional working condition, the operating efficiency has been improved.(3) Depending on Wilson design theory, with the goal of obtaining maximum coefficient tidal energy utilization, then considering about the influence of tip loss, optimization toolbox of Matlab software has been applied to iterative calculation on getting blade parameters. Power outputs under various flow rates have been simulated by using CFX, while variation curves about Cp-v have also been studied. Thus, accuracy of design method on reversible airfoils has been validated by comparing those results.In summary, reversible airfoils designed by reverse-jointed method can be well applied to bi-directional tidal turbines design method aiming at reaching their coefficient of energy utilization. Thus, this method can provide suitable references for follow-up development about bi-directional tidal turbines.