Fluid-Solid Coupling Analysis And Optimization Of Engine Cooling Fan

It's only about 30% of the thermal energy generated by fuel combustion in the engine that is converted into mechanical energy for effective energy.About 50% of the remaining thermal energy needed to be cooled by the cooling system.In order to meet the requirements of thermal dissipation for the cooling system,in addition to low temperature environmental conditions and high-speed driving conditions of the car,most of cooling system required cooling fans to increase the air volume.The cooling fan played an irreplaceable role in the engine cooling system.Its designing and operation condition were directly related to the thermal dissipation effectivity of the entire cooling system.If the cooling fan stopped running due to faults,the internal heat in the engine would be difficult to be dissipated,which might lead to serious consequence.Firstly,based on the advantages of ANSYS CFD software and ANSYS CFX software in the field of fluid analysis of rotating machinery,researched the difference and the application condition between the structural grid and the unstructured grid.The article provided a complete theoretical system for the accurate simulation of flow field in the engine cooling fan.It's introduced that the scheme of aerodynamic performance test and the layout of the wind tunnel for the engine cooling fan in the article.Based on the experiment,we simplified the cooling fan and established the aerodynamic performance calculation model of the inner and outer basins.It's also introduced that the method of meshing and boundary condition setting of fan steady flow field calculation.Finally,the calculation results of steady flow field are compared with the results of aerodynamic performance test.The result showed that the error range between the two parts was less than 5%.The result laid an important foundation of the following fluid-structured coupling calculation.Based on simulation results of the flow field,an analytical model of the cooling fan structure was established.It's the strength and mode of the fan structure that were analyzed during fluid-structured coupling with numerical simulation.The position of max deformation occurs at the top end of the fan blade.In High temperature environment,The working frequency of the cooling fan was58.4 Hz,the passing frequency of blade was 467.2 Hz.In order to improve the axial stiffness of fan blade,the design structure of adding aluminium alloy insert in the hub of fan impeller is proposed.The fluid-solid coupling analysis under high temperature environment is added to the cooling fan model before and after optimization.The structural analysis results of fan before optimization and after optimization are compared and analyzed.The axial deformation of fan blade after optimization is reduced and the operation of fan blade is reduced.The jitter value can improve the reliability design quality of the fan assembly.Additional inserts in the fan blade have little effect on the free modal analysis results of the fan assembly: The frequencies were close to each other and the mode shapes were similar;The influence of the pre-stress mode was also small with considering the fluid-solid coupling: The frequencies were close to each other and the mode shapes were similar.