Dynamic Characteristics And Correlation Analysis Of Low Velocity Impeller With Different Media

Turbomachinery can convert fluid energy in nature into mechanical energy,which is widely used in ocean current power generation and wind power generation.It is the main research object of using renewable energy in China.In the ’ 14 th Five-Year Plan ’,it is emphasized to pay attention to the development of wind power and hydropower energy.However,the current turbine is less economical to generate electricity in low flow velocity areas,and it is difficult to use fluids with a flow velocity of less than 1m / s.Therefore,the simulation model of the mechanical dynamic characteristics of the lowspeed impeller is established,and the correlation with the dynamic performance of the impeller in water and air is analyzed.The dynamic characteristics of a,b and c impellers in different media were obtained by experimental test.The simulation models of a,b and c impellers were established by Fluent software.The dynamic characteristics of impellers in different media were analyzed,and the correlation coefficients of impellers in different media were obtained.In addition,based on the test and simulation results,a new lowspeed starting impeller is designed.The hydrodynamic characteristics are analyzed by using the simulation model and the correlation coefficient,and verified by the vehicle test in the air.The specific research contents are as follows :1.The results show that the dynamic characteristics of a,b and c impellers in water and air are similar,and the angle of attack and different blade shapes all affect the starting performance and dynamic characteristics of the impeller.Through comparative analysis,the power factor of a,b and c impellers in water medium is greater than that in air medium,and the maximum power factor difference is 2 %,5 % and 0.4 % respectively,which conforms to the similarity theory,that is,the power factor similarity theory corresponding to the same tip speed ratio in different media.2.The dynamic characteristics of impeller a,b and c in different media are simulated by Fluent software,and the torque coefficient,flow field distribution and velocity vorticity change of impeller in different media are analyzed from the perspective of flow field.The results show that under the condition of low flow velocity,the maximum starting torque of impeller c is 2.01 N·m and 0.689 N·m respectively,and the energy conversion efficiency is the highest.At the same time,the correlation coefficient of the impeller in different media is established,and the simulation model of dynamic characteristics analysis of different media is finally obtained.3.A new impeller was designed to start at low speed.Four groups of impellers with different chord lengths and twist angles were designed by increasing the number of blades,increasing the twist angle and reducing the design tip speed ratio.Based on the calculation results of the simulation model,No.3 impeller was selected for vehicle test to verify the accuracy of the simulation model.Combined with the vehicle test results,the dynamic characteristic curve of No.3 impeller water medium test is obtained by using the correlation coefficient.The research results can provide theoretical basis for the design and optimization of low velocity impeller.