A Study On The Effect Of The Structure And Parameters Of Engine Annular Cooling Fans On Performances

An engine cooling fan which performance directly affects the energy consumption, emission and noise of an engine is an important component of the engine cooling system. With the rigorous requirement of circumstance protection and the continuous improved engine performance, the requirement of the engine cooling system is higher and higher. The development of efficient engine cooling fans becomes an important research project.The traditional process of cooling fan design is mainly the optimization design through test and empirical method. With the development of computer technology and calculation method, computational fluid dynamics(CFD) has been applied widely. CFD simulation has the features of short development cycle, low cost and showing abundant flow characteristics, which has become an important part of the process of cooling fan design and research.Firstly, the test of aerodynamic performance of engine cooling fans is introduced in this thesis, and the aerodynamic performance parameters of fans such as air volume, static pressure, brake horsepower, and static efficiency can be obtained through the test and relevant calculation. According to the test condition of aerodynamic performance of an annular fan, a CFD calculation model is developed in Fluent and used to calculate and to analyze the aerodynamic performance of the tested annular fan. The model is validated by comparing the measured and the calculated data. The flow characteristics of the annular fan are analyzed with the post-processing techniques of the software.Used the CFD calculation model, the relation between aerodynamic performance of an annular fan and the ring structures and dimension parameters is investigated. The results of the calculation show that the fillet in the ring of an annular fan will improve its static efficiency. The relative parameter on the axial direction has great influence on the aerodynamic performance of an annular fan, and each annular fan has the best static efficiency with a blade exposure rate. However, the radial relative parameter affects little on the static efficiency of an annular fan.Finally, the aerodynamic performance of annular fans with a rounded shroud, a plug-in shroud and a labyrinth shroud is analyzed contrastively. The effects on aerodynamic performance of an annular fan with a plug-in shroud and a labyrinth shroud are studied, which from the clearance between the shroud and the annular fan. The results show that the smaller clearance makes the aerodynamic performance of an annular fan better.