| After the reform and opening up, Chinese economic develops rapidly. Driven by strong electricity demand, coal and electricity production capacity is growing, which is currently able to basically meet the market demand. But the security of energy supply and energy environmental situation has been grim. In the "Thirteen Five" period, China’s economy is facing a new situation, economic transformation is imminent. Government put forward five development concepts including innovation, coordination, green, opening and sharing. The energy in the future will be clean, efficient, low-carbon and renewable. Marine energy will have great progress.In the field of ocean current power generation, the horizontal axis tidal current energy generation device occupies a major position in the market because of high energy utilization factor. The horizontal axis generating device is difficult to be started at low flow rates, hard to resist pressure at high velocity and be sealed underwater. As opposed to the vertical axis tidal current energy generation device, although the energy utilization factor is not high, it is easier to be started and not affected by the flow direction with stable structure.The hydrodynamic performance analysis of vertical axis tidal current energy turbine is similar to the vertical axis wind turbine power generation. According to the theory based on the mathematical model can be divided into three categories:(1) a method based on momentum theorem,(2) vortex theory based methods,(3) CFD method based on solving the N-S process. Three laws of physics(the law of conservation of momentum, conservation of mass, conservation of energy) are the basis of computational fluid dynamics. Fluent main task is to solve incompressible viscous fluid motion equations, the N-S equation. This paper discusses the turbulence model, the rotate model and choses rotational coordinates method to establish the motion model that can simulate the rotating blades and the interaction between the flow field, which accurately describe the flow field characteristics of blade rotation area.This paper analyzes the influence to hydraulic turbine with different number of blades by ANSYS Fluent and simulates the different number of blades of the turbine’s case at a flow rate. Then author gets pressure, turbulence intensity and velocity magnitude contours. By analyzing the pressure on both sides of the blade, Savonius-blade produces positive torque to drive the turbine rotary motion in the counterclockwise direction in one, three, four-quadrant. As the same time, they make negative torque in the second quadrant to hinder turbine rotary motion. 2 and 3 blade turbine’s pressure gradient distribution is more uniform in the larger area which makes the turbine obtain stable torque easily. By analyzing the image shows that the turbulence intensity for 2, 3 and 4 blade Savonius turbine is more evenly distributed compared with 5-8 blades. This can result in cavitation and reduce the efficiency of the turbine when it works. From the point of view of energy efficiency, 2--4 blades Savonius turbine have a better performance. By analyzing drag and torque graph, 2 blades Savonius turbine can achieve greater resistance and torque, it is possible to obtain greater efficiency.A new innovative design of two Savonius rotors coaxially in the opposite direction is presented in the paper which is different from the traditional design. The traditional generator has only a pair of stator and rotor and matched with traditional Savonius rotor. Enlarging the relative speed between the magnetic pole and the coil pole by making the two poles rotate in the opposite direction in the innovative Savonius current turbine design. In this way, it can enhance the power generation efficiency of the Savonius current turbine.Savonius rotor is a typical style of vertical-axis turbine. Author selects FRP material as the impeller after analyzing the advantages and disadvantages of the main material. The paper makes a study on bearing design and verification to ensure the safety of the device. Through the ANSYS CFX module, the article has received the pressure turbine cloud, the speed cloud and the distribution of stress and deformation of the impeller structure. After analyzing the finite element simulation result, the torque during rotation is acquired. According to the calculation formula, the power can be calculated.At the end of this paper, the design idea of the power flow energy generating device is considered, and the corresponding flume experiment is designed. The experiment was used to verify the performance of Savonius blade with 2-4 impellers, and the similarity between the theoretical calculation by the computer simulation and the performance of the small tidal energy generation device. The results show that, in the case of the same relative velocity, the torque of the 2 blades Savonius impeller is slightly larger, and the result is the same as that of the simulation. The measured power generation is 277.18 W, and the results calculated by the computer simulation have little difference, the error is 6.1%, which belongs to the reasonable error range, which verifies the validity of the power generation device. |
PDF Full Text Request