Abstract
As complex axial flow machinery, lots of vortex distributes around engine cooling fan. Negative circumferential vorticity (CV) leads to low efficiency and power loss. In order to investigate the adverse effects of CV on aerodynamic performances of the fan, a mathematical physical relationship between CV and aerodynamic performances is established, and the location of the negative CV is found by the method of vorticity analysis. An outer ring is designed for annular cooling fan, and the parameter of aperture rate is defined in this paper. Both static pressure and power loss is overall considerate during the optimization process of the outer ring, and putting forward that optimum range of the aperture rate is different for various annular fans.
Highlights
Axial cooling fan is an important component of engine cooling system
According to Ref. [1]: for the general axial fan, the main source of secondary stream loss comes from the tip leakage vortex
Refs. [2,3,4] tended to performed the structure optimization of fan by traditional method of Computer Dynamic Fluid (CFD), the calculation model of fan-flow-field was built and the distribution of pressure and vortex were further analyzed, and the optimization design of structure was performed by their engineering experience
Summary
Axial cooling fan is an important component of engine cooling system. According to the structure of the fan, it includes annual axial cooling fan and common one. [2,3,4] tended to performed the structure optimization of fan by traditional method of Computer Dynamic Fluid (CFD), the calculation model of fan-flow-field was built and the distribution of pressure and vortex were further analyzed, and the optimization design of structure was performed by their engineering experience. [5, 6] pointed that vortex is the truly source of both pressure lift and resistance, the resistance one does negative work in the flow-field, and the objective of vorticity analysis (VA) is to find the location of negative vortex distributes on blade surfaces and to carry out local optimization. The VA analysis method is widely used in high Mach number (> 0.7) axial machines structure optimization, such as high-pressure gas compressors and turbines It is rarely used in low Mach number (< 0.3) kinds, such as axial cooling fans.
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