An optimization approach from hydrofoil to blade has been developed and the CFD analysis for the optimum horizontal axis marine current turbine has been carried out as well. Xfoil is applied for 2D hydrofoil analysis. It combines with Matlab under a frame of Genetic Algorithm (GA) to optimize the hydrofoil. The program obtained optimum new hydrofoils within the constrained range in order to get a linear combination of lift or drag coefficient and twist angle. Finally, a program has been developed based on the Blade Element Momentum Theory (BEMT) for evaluating the hydrodynamic performance of the whole blade. After that, the RANSE solver has also been employed for validating the results. The flow details under uniform inflow and actual shear current inflows have been computed and discussed. The calculation results are compared with the published data. The blades with the optimized hydrofoils have achieved optimum energy efficiency coefficient and thrust force.
Among the extraction devices, the marine current energy is the most promising energy and can fulfil in the inland river or at the sea strait. According to the movements, the marine current extraction devices can be divided into reciprocate and rotation. Horizontal Axis Marine Current Turbine (HAMCT) and Vertical Axis Marine Current Turbine (VAMCT) are two major categories of rotation devices.
There are lots of research on the HAMCT, especially experimental and numerical work on marine current turbines (Bahaj and Batten et al.,2007) (Bahaj and Molland et al.,2007). The high efficient hydrofoils for the MCT are the hot issue while their performance is gaining more and more interests in designing marine current turbines. XFoil and Blade Element Momentum Theory (BEMT) are normally used as analytical tools(Ahmed, 2012) (He, 2013). However, the previous researches are limited in finding an indirect way to optimize the hydrofoil and combine the 2D hydrofoil to 3D blade. By employing Xfoil and Matlab to run a hydrofoil optimization program based on GA, a blade design program via BEMT to analyze 3D blades has been developed in present paper to complete optimization design of MCT blades. At last, RANSE solver has been used to validate the results with both uniform inflow and shear profile inflow inlet conditions.
