| The supply of fossil fuels has become increasingly tense,and environmental problems have been intensified worldwidely.As a clean and pollution-free green renewable energy,the tidal current energy(TCE)has been developed and utilized as an effective way to alleviate the energy shortage and environment pollution reduction with its advantages of large reserves,wide distribution,high predictability,little environmental pollution,etc..The main device of development and utilization of TCE is hydraulic turbine mounted on the carrier,which constitutes the power generation system converting the kinetic energy to electrical energy.At present,there are many classifications of tidal current generation devices and each has a unique application background and advantages.According to the carrier,it can be divided into the pile foundation type,the base type and floating type.According to the turbine,it can be mainly classified as horizontal axis type and vertical axis turbine type.Among them,power generation device of turbine with vertical axis floating incorporates their characteristics respectively with its simple structure,easy manufacturing technique,low cost,low maintenance and management cost,ideal adaption to the flow changes,and low draft requirements.In recent years,it has become a heated topic,and experiment demonstration units have been run in China,Italian and some other countries.However,the present researches of tidal current power generation devices of vertical shaft turbine are focused more on floating carrier and mooring system study than on the vertical shaft turbine,floating carrier and mooring system under the action of coupling,the trend of the power generation device performance prediction research.And it is the key which is restricting the tidal current power generation device design,experimental demonstration study and engineering application.Therefore,this dissertation provides a theoretical basis and technical support in such devices research and engineering application based on the researches of hydrodynamic performance of floating tidal current energy power generation unit of the vertical axis turbine,in this paper,the establishment of tidal current energy generation device test prediction methods,platforms and numerical prediction method about hydrodynamic performance.In terms of the test methods and design of floating tidal current energy power generation device of turbine with vertical axis mooring,this dissertation first determines the scale ratio of model tests according to the prototype of generation device and ship model towing tank situation,researches the connection design of catamaran model and the turbine model,researches the measurement methods of center of gravity of power generation device model and moment of inertia,designes and developes measurements and modulation devices of the center of gravity and moment of inertia,measures and adjusts the model's center of gravity and moment of inertia.Afterwards,the simulation of mooring point and anchor chain is conducted respectively,the mooring simulation achieved through mooring rack,and anchor chain simulations achieved through the mooring.,The instruments and equipment of mooring experimental research are then chosen to carry out the measurement and layout scheme,describe the method of the installation of mooring rack and the mooring pretension adjustment,and give the test conditions.Finally,it forms the test platform and test methods of floating mooring tidal current energy generation device based on the ship model towing tank.In terms of the mooring test research of floating tidal current energy power generation device based on vertical shaft turbine,this dissertation studies the free attenuation and mooring attenuation characteristics of floating tidal current energy power generation device based on vertical shaft turbine,then measures and analyzes the portfolio model under free state in roll and pitch decay,portfolio model under the mooring condition of rolling,and pitching attenuation condition and bow wave attenuation respectively.Then it studies mooring force posture response characteristics in uniform flow and combination mode's response characteristics of device model and introduces and analyzes the experiment of some phenomenon.Afterwards,it carries out the comparative experimental studies on water turbine in turning and not turning conditions in the uniform flow,compares and analyzes the mooring line tension,combination model of the attitude response,and the lateral displacement of the test model under the two conditions,and draws the conclusion.It has carried on the mooring test study on regular wave environment.It also studies the wave height and frequency's influence on model's mooring line tension and movement.Finally,the devices' mooring line tension and posture response is studied and analyzed under the irregular wave environment situation.In terms of the basic theories of the overall performance of the floating tidal energy generating device of turbine with vertical axis,the dissertation first gives a simulation method about the vertical axis turbine,including the basic equations about simulation,RANS equations,turbulence model and near wall region approach,discrete methods,and simulation methods of free variables declination.Domain analysis theories are then advanced based on the three-dimensional potential flow theory,including the definition of the coordinate system,the solving of the liner speed,the first wave force,the average wave drift force,and the second-order wave force transfer function matrix.Based on all above in this part,this dissertation gave the coupled time-domain analysis theory of set hydrodynamic performance analysis;established time-domain coupled motion equation,gave the determination method of wind power,current force and wave power,and gave the turbine load coupling approach.In the overall performance research of the floating tidal current energy generating device of turbine with vertical axis,this dissertation conducts the numerical simulation of the hydraulic turbine current load conditions according to the basic theory in Chapter 4,fits the turbine force data to compute equivalent added mass and damping produced by the rotation of the turbine Then the floating carrier of floating type tidal current power generation device are analyzed in frequency domain radiation and diffraction.Finally,the influence of the turbine's rotation is taken into consideration to study the power generation device hydrodynamic performance by means of the coupling calculation and to forecast the cable tension and movement response of the power device.Typical working conditions are accordingly chosen to be compared with the test results to verify the validity of the numerical prediction method.In the overall performance research of the the floating tidal energy generating set hydrodynamic performance with buoys,the dissertation first devised buoy structure and mooring connection,then conducted the radiation/diffraction analysis results with the frequency domain in Chapter 4,researched the floating tidal energy generating set with buoys and generating set's mooring tension and motion response,and analyzed the affect about buoy for set performance. |
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