Computational Fluid Dynamics Based Optimal Design of Vertical Axis Marine Current Turbines
Abstract Marine turbines are being increasingly used to harness kinetic energy of water and convert it into other useful forms of energy. Widespread commercial acceptability of these machines depends upon their efficiency. This largely depends upon the geometric features of the marine turbines such as number of blades, shape of blades etc. Researchers have been using experimental facilities to optimise these machines for maximum power generation. With the advent of advanced computational techniques, it has now become possible to numerically simulate the flow of water in the vicinity of marine turbines and monitor their performance output. In this work Computational Fluid Dynamics (CFD) based techniques have been used to analyse the effects of number of blades within the stator and rotor, of an in-house built Vertical Axis Marine Current Turbine (VAMCT), on the performance output of the turbine. Furthermore, an effort has been put forward towards better understanding of the flow structure in the vicinity of the blades during transient interaction between rotor and stator blades. This study provides vital information with regards to the flow sensors’ requirements and placements in order to monitor various blade configurations of a VAMCT in real world. The results of this study show that the torque output from a VAMCT is a strong function of blade configurations and there is a significant degradation in the performance output of marine turbines as the inequality between the number of rotor and stator blades increases. Hence, CFD has the potential to optimise the design of marine turbines and can be used as a potential modelling tool in the near future for on-line health monitoring of such systems.
Using of CFD software for setting the location of water stream micro turbines
The aim of this work was to estimate the efficiency of CFD software in calculating flow velocity magnitude in natural water streams. These kinds of estimations are essential for setting the locations of water stream micro turbines. These devices can be useful to provide electricity in areas remote from power generating facilities or as backup power supply in case of power grid failure. The analysed water stream has length of 100 m and its average slope was approximately 10%. Water velocity varies in the range from 0.5 m3 *s−1 to 5 m3 *s−1 . Additionally, the influence of ground roughness on the stream velocity was also an important factor. Results proved to be satisfactory. In the analysed stream, velocities were in a range which allows the proposed micro turbine to be effective. Calculation grid created by CFD software did not have many areas which may raise doubts. Also, the influence of changes in the ground roughness factor was noticeable. Preliminary CFD simulations allow to estimate where in the stream the micro turbine will be most efficient. On the other hand, despite these calculations, profitability and return on the investment still can be questionable.
Hydrofoil optimization and experimental validation in helical vertical axis turbine for power generation from marine current
Abstract A kind of hydrofoil, which is especially for use by helical vertical axis turbine for power generation from marine current, has been optimized by means of traditional genetic algorithms combined with hierarchical fair competition model. Bezier curve is used to parameterize the hydrofoils and numerical analysis is also introduced to evaluate hydrodynamic performance. Special fitness function as well as modified total lift–drag ratio is discussed in detail. Turbine performance tests and flow visualization experiments by PIV are conducted in order to draw a comparison between the optimized and two other competitive hydrofoils. The experimental results demonstrate that the optimized is more suitable to marine condition and beneficial to turbine efficiency improvement, and can be expected to act as a prospective hydrofoil for helical vertical axis turbine.