Dovetail of a steam turbine is a one of the most important factors which effect reliability and performance of a turbine plant. In these years, however, the condition under which steam turbines are operated has become severer. The increase in centrifugal force, due to variation sway and fluctuation of load, is listed. As quite heavy load workes on a turbine blade structure. It is important to estimate stress distribution with experiments. Althouh there are many reports about turbine blades, most of the results are examined by two dimensional stress analysis and static stress. In our present study, we have analyzed the stress distribution of turbine blades with practically simulated turbine blades by means of three dimensional stress analysis method in frozen photoelasticity.
There are two types in turbine dovetail. One is a Straddle type dovetail, the other is a Christmastree type dovetail. We obtained stress distribution and stress concentration factorin terms of strength comparision between two types. The results are shown from the viewpointof stress concentration. And the normal stress around the surface and the shear stress on the Straddle type dovetail are higher than those of Christmastree type dovetail.
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