Research On The Interaction Theory Of Flowing Air And Wind Turbine Blade And Its Application

The demand for sustainable energy has increased over the past few decades,not only due to the excessive use of fossil energy sources but also due to their massive carbon emission footprints.Among all available alternatives,wind energy is an important one and has gained priority all around the world.The blade of a wind turbine plays an essential role in the extraction of wind energy and harnessing it into electrical power.The airfoils are of significant concern since sections of the blade are composed of different airfoils.Overall,the efficiency of wind energy utilization is dependent on blade design and airfoils used to design the blade Keeping the blade as a center of research objective,the interaction between flowing air and blade surface and its impact on wind energy efficiency are studied in detail to improve the aerodynamic performance.Initially,the interaction of flowing air and the windward and leeward faces of the blade is studied as the direction of air impacting the blade has a significant influence on the utilization and conversion rate of the wind turbine.Improvement in wind energy utilization and the conversion rate of wind turbines has been the focus of experts in the field of wind power.Therefore,the law of momentum is used to find the influence of interaction and air outflow angle at windward and leeward of the blade.A theoretical model and its corresponding formulas of the air outlet angle at blade windward/leeward trailing edge are put forward to improve the wind energy utilization and conversion rate.The result of the study and conclusion provide guidance and beneficial attempt for the improvement of wind power utilization and conversion rate of wind turbine blades.In the second step,the design of airfoil has been studied in detail.An optimized airfoil(named and referred to as SJX)is designed based on the line theory by the weight analogy to pressure difference of airflow.The different characteristics of SJX airfoil,such as lift,drag,and lift to drag ratio is compared with NACA 2409-34,NACA2410,and RK40 at fixed wind velocity and different angles of attack(AOA).During the study,it is found that SJX airfoil and NACA 2409-34 airfoil have very similar characteristics.Based on the Wilson method,blades for horizontal axis wind turbine(HWAT)using SJX and NACA 2490-34 airfoils are designed.Different performance parameters such as velocity distribution,pressure distribution,and power are compared under variable wind velocities at different radial sections of the blade from the center of the rotor using a turbulence model of computational fluid dynamics(CFD)in ANSYS FLUENT.The result of the study suggests that the performance of SJX based airfoil and blade is much more optimized.Finally,the impact of the chord and twist angle in the designing of a blade is studied,and a new theoretical model is presented to find the optimal chord and twist angle of a blade for the optimized performance of wind turbines.The design theory of the element-stream aerodynamic shape of the blade based on the Euler method with the consideration of blade number,hub radius,and air resistance is devised.A study is carried out to design a 1.2 MW wind turbine.The aerodynamic shape of the blade is intended using Glauert,Wilson,and optimizing the chord length and twist angle of blade utilizing the theory of the element-stream aerodynamic shape of the blade based on the Euler method.The data about the aerodynamic performance of the wind turbine was obtained under 20 working conditions.For the proposed method,the blade is designed using obtained chord lengths(ranging from 5.1m tol.1m)and twist angles(ranging from 10 to 350)having cross-section(ranging from 0.1m to 1m)for each element.The utilization rate of wind energy of the wind turbine designed is 0.45(wind speed?8m/s),which is higher than the planned utilization of 0.42.Therefore,the proposed method has not only better aerodynamic performance in the low wind speed,higher wind energy utilization rate,and low starting wind speed but also low manufacturing cost.Proceeding further flow field around the wind turbine designed is analyzed employing distribution gradient for the flow velocity and air pressure on the windward and leeward side of blade elements at the different selected radius.Ultimately,the proposed blade design provides a theoretical reference for the development and efficient utilization of low wind speed wind resources.The design theory of the element-stream aerodynamic shape of the blade on the Euler method is a theoretical exploration and beneficial attempt for aerodynamic shape design of the wind turbine blade,which provides a new idea and reference for the research about blades.