| The main research of this paper is the axial cooling fan for vehicles.In the design parameters of the fan,the distribution of the torsion angle and the forward sweep angle at different radiuses have a great influence on the aerodynamic performance of the fan.In this paper,a mature optimization algorithm is used to optimize the fan design parameters,and the optimization results are compared with the experimental results.The influence of the specific design parameters on the aerodynamic performance of the fan is analyzed.The classical leaf-momentum theory of wind turbine is applied to the axial cooling fan of the vehicle,and the theoretical model of the relationship between cooling fan geometry parameters,fan speed and air volume-torque is established.Based on the differences in energy conversion between the cooling fan and the wind turbine,this model corrects the classic leaf element-momentum in the direction of leaf element load,boundary conditions at the entrance and exit,and so on.Realize the application of leaf-momentum theory in fan air volume and torque theory calculations.Subsequently,based on experimental measurements and theoretical calculation methods,the fan air volume and torque theoretical calculation model were verified.The results show that the theoretical calculation method of fan air volume and torque not only can reflect the variation law of air volume and torque with fan speed,but also has high calculation accuracy.In the model studied in this paper,the average error between the air volume theory algorithm and the experimental results is 3.57%,and the average error between the torque theory algorithm and the experimental results is 1.51%.Based on the theory of the leaf-momentum momentum theory for calculating the air volume torque,using the optimization of the particle swarm algorithm,when the target air volume is reached at a specific speed,the torque is used as the objective function to achieve the minimum torque and distribution of the cooling fan chord length and twist angle.After optimization,the distribution of optimized chord twist angles at different radii was obtained.A CFD simulation model was established.The related theories of fluid mechanics and turbulence models were briefly introduced.The number of grids,including the number of grids in the rotation domain,was used to verify the accuracy of the simulation.The effect of the number of grids on the simulation accuracy of the fan was obtained.The simulation analysis of the turbulence model's choice was made,and the influence of different turbulence models on the fan simulation accuracy was obtained.Different parametric sweep models were established and their flow was simulated using computational fluid dynamics.The effects of forward sweep angle on the cooling fan flow,air flow and torque were investigated under different fan speeds.The results show that the average relative error between the CFD calculation value and the experimental measurement value is 3.08% in the calculation of the air volume,and the average relative error between the CFD calculation value and the experimental measurement value is 2.79% in the resistance torque.With the increase of the forward sweep angle,at the same rotational speed,the average pressure of the air at the entrance of the fan cascade continues to increase;within the cascade flow path,the pressure gradient between the blade lift surface and the blade suction surface gradually decreases;the blade lift surface The pressure difference with the suction surface gradually decreases.As the forward sweep angle increases,the velocity of the air at the inlet of the fan cascade gradually decreases at the same rotational speed,and the increase of the air velocity gradually decreases in the cascade flow passage.As the forward sweep angle increases,the air volume of the fan gradually decreases at the same rotation speed;the resistance torque of the fan gradually decreases. |
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