Study On The Principle Design And Hydrodynamic Performance For A Swing-type River Generator

As a clean and pollution-free green renewable energy,the river current energy has many advantages with wide distribution,large reserves,high predictability and little environmental pollution,etc.The traditional utilization of the river current energy is the construction of hydro power station.Based on the topography gap,the river high potential energy is converted to high speed flow the impact of power turbine.However,the use of the kinetic energy of river becomes an alternative way to generate electricity in the vast plains or river ways of less prone to dam.The core equipment of river kinetic energy generating system is zero head or extremely low head generator to become the focus of research in recent years.The existing flow kinetic energy conversion devices have two categories with rotating-type and swing-type.The key technologies of rotating turbine unit and its hydrodynamic performance studies have conducted a lot of research work with rich achievement.However,rotating-type turbine device is difficult to realize single machine of large-scale structure in the shallow and low flow river way.The swing-type device has an obvious superiority with adapting to unidirectional flow characteristics and owning relatively simple structure,compared with rotating-type device.Based on lift of the interaction between water flow and wing or the principle of vortex-induced vibration,swing-type energy conversion device can get energy or propel.For river power generation,the understanding of the hydrodynamics problem,such as the energy characteristics of linear swing-type device,the law of design parameters,is inadequate.The further research on the mechanism of energy conversion,device configuration design,hydrodynamic performance and load is needed to be carried out.So,based on the background of the hydrodynamic design of swing-type device,the paper studies a new linear swing-type device suitable to the conversion of river energy by theoretical analysis,model tests and numerical simulation method,and carry research on conceptual design,prototype design hydrodynamic performances and load,which provides theoretical methods and the design techniques for developing a new kind of energy conversion device with important significance.Firstly,the paper has introduced the characteristics of the kinetic energy of the river,resources distribution.Then,the paper reviewed and summarized research progress and present situation of rotating-type and swing-type conversion device from the aspects of the device development,key technology,theory and experimental study.Finally,the paper puts forward the main research direction,key problems and solutions.In view of river kinetic energy conversion and prototype design for power generation,considering the shallow river way and the unidirectional river characteristics,the paper puts forward a new type of rivers kinetic energy power generator—linear swing-type generator.Based on research of prototype and structure design,the paper puts forward overall scheme and system layout of the new device.The device uses symmetrical straight airfoil blade as water capacity components,a set or more sets of vertical blades installed on the straight line slide way across the river and both ends of the straight line slide way respectively fixed on both base of the river bank.With an affection of the action of the river,the blade group makes linear reciprocating motion along the way,converts flow kinetic energy into mechanical energy of pendulum motion on a straight line to drive linear generator(or rotating generator)to generate electricity.The main features of the device are the whole machine unit across the width of river way can be designed as far as possible to achieve a single set of maximum capacity.The device owns simple structure,compact layout,power system and mechanical drive system are installed above the water surface to reduce the water sealing difficulty.It is easy to carry out integration design of power generation and bridge construction to improve the comprehensive economic benefits.In view of hydrodynamic numerical simulation method of linear swing-type river generator,based on the viscous CFD theory and software,a hydrodynamic numerical simulation method has been set up to be suitable for the linear swing-type river generator.The influence of the boundary setting of steady and unsteady flow field,meshing generation,partition technology and turbulence model on the numerical results is discussed.Through CFD numerical simulation,the flow field and hydrodynamics of the device has been studied under the action of reciprocating motion.The power characteristics,hydrodynamic load characteristics of energy conversion with symmetrical airfoil straight blade swing-device have been given.And the change rule of the energy conversion and hydrodynamic force with the blade airfoil,horizontal and vertical distance,blade number,blade installation angle,the compactness,movement speed ratio have been revealed,providing a theoretical for the design of linear swing-type energy generator hydrodynamic characteristic parameters,blade layout design and its type selection.In view of the reciprocating reversing characteristics of swing-type river generator,based on the CFD methods,under the action of water flow,a detailed study on the flow characteristics and the force has been carried out in the process of reciprocating swing-type reversing.The analysis for the different types and layout reversing body(sinusoidal,rectangular reversing body)at the two ends of the linear swing-type device with effect on flow field interference and reversing effect has been carried out.The shapes of reversing body,layout scheme and the position of blade shaft have been given.In view of the principle experimental verification on the swing-type device and the verification of CFD simulation method,a prototype test system of swing-type device has been founded,and the test platform of the hydrodynamic characteristics of swing-type device has been designed and manufactured.The test method of the prototype performance and loads has been given.According to the different design parameters and operating conditions,the experimental studies on the performance of the system and observation of phenomena have been carried out.Based on the NACA0018 blade,the test for the steady state,the reversing state,the fixed load with changing the blade angle in the condition of the small blade,the fixed load experimental with changing the blade angle in the condition of the large blade angle and the fixed blade angle experimental with changing the load of swing-type device have been carried.The comparison between the results of the prototype test and the calculated pattern of numerical simulation has been made.At the same time,the validity of the new linear swing-type device and the numerical simulation methods has been verified by experimental study.The improvement direction of principle of the prototype has been pointed out through the experiment.Then again,this paper also refers to the improved swing-type generator-rectangular turbine which.The paper gives the schematic structure and working principle of a rectangular turbine,and outlines the motion and dynamic properties of the blades.Then,by using CFD numerical simulation methods,an analysis about the influences from compactness,blade mounting angle,velocity and other parameters on the turbine performance has been given.In addition,the paper designs an experimental rectangular turbine model and a testing platform,the hydrodynamic experiments have been conducted and the test results are given.Research has shown that if the flexible material blade is used,the device can be used in the one-way flow,which can also be used in the two-way flow natural environment.