クリスマスツリー型蒸気タービン翼根溝の引張荷重と遠心荷重による応力分布の比較

抄録

In turbine design, because the joint between the turbine blade and the rotor bears the largest stress, it is important to study the stress at this position. The fir-tree type is one of the most efficient joint configurations for blade fastenings.
Many papers have reported on the fir-tree turbine blade, but these mostly dealt with experiments using two-dimensional analysis and tensile load, rather than centrifugal load. Data are of minimal value if the stress distribution of tensile load is evaluated in the same light as centrifugal load. We therefore experimented on the fir-tree straight entry type with threedimensional stress analysis in frozen photoelasticity. The loading methods were given with both tensile and centrifugal loads.
The results: Radially in both the tensile and centrifugal loads the highest stress concentration point was the tip serration. Axially in the tensile load the stress concentration at the edge was low. In the centrifugal load the distribution was uniform.