多翼ファンの設計技術に関する研究(第2報,軸系のねじり振動モデルの基礎的検討)

This study aims to clarify deformation and stress generation mechanisms in a multiblade fan under static and dynamic torsional moments, and to establish a simple lumped inertia model for the dynamic analysis. Static and dynamic torsional tests were carried out to investigate the deformation and stress of the blades. Numerical calculations of the deformation and stress using the finite element method were also carried out under the same loading conditions. By comparing the experimental results with the numerical ones, the generation mechanisms of the deformation and stress of the blade were clarified. The results of these investigations are as follows. The relative displacement between the main and side plates causes the bending deformation in the flatwise and edgewise directions and the torsional deformation of the blade under the static and dynamic torsional moments. The stress caused by the deformation in the flatwise direction mainly governs the strength of the blade. Good coincidence is found between the static stress distribution and the dynamic one in the first mode. This means that the simple lumped inertia model is suitable for further dynamic analysis of the rotating fan shaft system.