Study On The Performance Of Diversion Device With Low Flow Rate

Tidal current energy is a kind of inexhaustible, clean and renewable energy. Development and research of the technology and equipment of electric power generation from the tidal current energy has important strategic significance and social and economic benefits. Tidal current energy capturing device is the core of the electric power generation system and the impeller is a key component of the tidal current energy capturing devices, so it is an effective way to improve the energy capturing efficiency of the impeller by setting up a fairwater sleeve around the impeller to increase tidal current velocity.In the paper,the type of fairwater devices was studied mainly on the basis of various types of tidal current energy capturing impeller was analyzed at home and abroad,then the concepts and methods of outer fairwater is proposed on the basis of inner fairwater existing methods.Three streamline curve was analyzed and chose circular curve as the optimize line, then the flow fields of the tidal current created by the inner fairwater sleeve and outer fairwater plate were numerically analyzed by using the CFD method and related software tools. Analysis results show that the effect of velocity increase of inner fairwater sleeve is obvious and the outer fairwater plate is about 65% of that with the inner fairwater sleeve.moreover, the tidal current velocity increases first and then decreases along the direction perpendicular to and away from the outer fairwater plate, and this feature can be fully utilized by the kind of impellers with negative energy capturing region to improve the energy capturing efficiency.In order to verify the correctness of the analysis results of inner and outer fairwater, the tidal current energy capturing impeller and its hydrodynamic performance experiment testing system was designed and manufactured on the basis of laboratory pool condition and the relative motion principle. Then the performance of horizontal and vertical axis impeller as well as fairwater sleeve was tested.It can offer preliminary basis and technical reference for the sea trial.According to the principle of inner and outer fairwater and its performance characteristics, this paper proposes a new fairwater catamaran type structure, it integrate inner and outer fairwater function. Then designed and manufactured the floating catamaran type comprehensive experimental to capture energy and generate power and desalinate seawater. The effect of catamaran’s fairwater and impeller’s energy capturing has test on the sea based on this platform. Test results show that the effect of velocity increase of fairwater catamaran type structure is obvious, tidal current velocity has increased 28% and 13% with inner and outer fairwater respectively. Moreover, the fairwater effect of measured in sea coincide with simulation data perferably.