J055021 数値流体解析による建設機械用冷却ファンの高性能化に関する研究(〔J055-02〕流体機械の研究開発におけるEFD/CFD(2))

Abstract

We have developed a new design tool, which can optimize high performance blade shapes of a cooling fan for an excavator. The developed tool can take account of static pressure efficiency, aerodynamic noise and production cost by computational fluid dynamics (CFD) and numerical optimization. The cost was evaluated by volume of the blade. The performance of the fan, namely static pressure efficiency and aerodynamic noise were calculated using commercial CFD software based on an incompressible Reynolds-averaged Navier-Stokes (RANS) solver. Numerical optimization using a genetic algorithm (GA) was used for determining the optimized shape of the fan. The baseline shape of optimization was a blade shape of current product. The design variables were blade length at hub, mean, and tip in span wise direction. We confirmed trade-off relation not only between static pressure efficiency and volume of blade but also between static pressure efficiency and noise level. We selected the optimized blade shape on the condition that the static pressure efficiency became maximum, the volume of the blade and the noise level were almost the same as baseline shape. The static pressure efficiency of the optimized shape was increased by 5 % than that of the baseline shape. We also confirmed that the difference in flow field between the baseline and optimized shapes was strength of vorticity and total pressure loss near the trailing edge caused by tip leakage flow. This difference in flow field influenced static pressure efficiency.