Research On Hydrodynamic Characteristics Mathematical Model In Tidal Current Energy Test Field

Currently, the energy crisis and environmental pollution have been the two major problems to the whole world. As a kind of green clean renewable energy,tidal current energy has very considerable development prospects because of the large storage,good predictability, environmentally friendly and so on. Many countries, which have rich marine resource, have successively formulated the corresponding policy and strategic objectives to promote research progress vigorously in tide power generation technology, and some of the tidal current energy test field has been built. So, in order to understand the influence after placing tidal turbines into flow field and optimize the design of berth, this paper chooses the Putuo-Hulu islands tidal energy demonstration project in Zhoushan as the study area, and using two mathematical models to simulate the near-field and far-field influence on hydrodynamic conditions caused by tidal turbines.Firstly, a briefly introduction from the perspective of numerical simulation has been given in this paper, which is about the research methods and conclusions proposed by scholars at home and abroad on hydrodynamic characteristics in tidal current energy test field. On the basis of energy equation, the author puts forward a method to generalize tidal turbines by calculate the path resistance loss between the upstream and downstream flow section and the equivalent roughness. Then, a 3D model of local flow field which contains the turbine is been built. By applying commercial CFD software and setting seven kinds of turbine’s rotate speed, we can see the similarities and differences in velocity distribution between seven sets of results. According to the turbine generalized method, we can calculate the equivalent roughness and comprehensive roughness of each set, and in turn conclude the relation between flow velocity and comprehensive roughness, which is applied to the specific grid nodes in 2D tidal current mathematical model of tidal test field. In this way, we can simulate the influence of turbines by changing the roughness of grid nodes where turbines placed. According to the results of 2D model calculation, we can analyze the hydrodynamic influence’s degree and range in far field in three simulating cases,respectively when 5 devices in each berth under a tidal wave cycle,only one device in certain berth under the whole tidal process and 5 devices in each berth under the whole tidal progress. It turned out that the size of affected zone that is made by turbines is connected with Flow velocity and terrain near the berth. The further you away from turbines, the smaller incidence to flow field. Overall, The influence degree of the devices to the far field flow is small, as is shown, the minimum velocity variation is about 2%,and the maximum variation is under 8% of the flow velocity before turbines is placed.