Optimization Design Of Impeller With Low Flow Rate And Energy Flow

In 20 th century, fossil energy represented by oil has pushed the rapid development of human social civilization. However, with population explosion and the excessive exploitation of earth resources, energy is increasingly in short supply. Meanwhile, the use of fossil resources has also caused increasingly serious environment pollution。 Human must do something to prevent it from deteriorating and promote renewable energy sources. As sustainable development and low-carbon economy has become a global consensus, developing and utilizing new energy resources has become a new economic growth point. However, china is a country of large population and scarce resources. It is imperative to develop and utilize new energy resources in this country. The utilization of tidal power generation at high efficiency can sharply relieve the plight of energy deficiency.In horizontal-axis tidal power generation device, the importance of is self-evident as the part capturing energy. The design of pedal can directly affect the efficiency of power generation. Considering the slow flows of the seawater along most of the sea coast in our country, it has become an urgent business to optimize the design of paddle for horizontal-axis tidal power generation at slow flow rate.Traditional paddle design directly uses wind power generation device, making use of the lift force caused while the water flows past the paddle.Flowing around the wing section and different flow rates on the outer surface can make a higher surface pressure at below than above, and thus create a lift force from vertical incoming flow resultant velocity. The component is the power it captured, but that does not work at low flow-rate offshore areas. Pressure differential lift force is in direct ratio to flow rate; lower flow rate can sharply drop energy capturing efficiency of the paddle. The thesis proposes a design method for the paddle, different from the traditional design based on wind power generation. Due to the paddle, the water flow breaks down as it goes past it. In this way, the paddle revolves with the power from the impact of seawater vertical to the effluent. Based on blade element theory, the thesis has made analysis on the impact upon paddle and built a dynamical model. Under the conditions of maximum capturing efficiency, it adopts nonlinear optimization to get paddle design parameter and thus forms the outline of the paddleThe thesis has designed two paddles for tidal power. One is designed on the basis of the captured impact power, and the other on the basis of captured differential pressure power. It analyzes the difference of the two paddles in chord length and pitch angle, and processed the paddles in real practice. It makes experiments with the designed paddle testing system, and by comparison of the optimized and unoptimized paddles, it finds that the paddle designed with the captured impact power can obtain higher power in slow flow condition, and thus proves the feasibility and effectiveness of the optimization design method.