STATIONARY TURBINE BLADE HAVING DIAPHRAGM CONSTRUCTION

摘要

56,937 A steam turbine blade has inner and outer rings which are integrally formed with an airfoil. A plurality of such blades are joined by welding the inner and outer rings to form an annular nozzle assembly. The diaphragm structure of the inventive blades offers improved performance over blades of similar length in that performance is improved due to smoother transition between the airfoil and the inner and outer rings as compared to conventional segmental assemblies in which a forged airfoil is welded to inner and outer rings. Furthermore, the present invention allows a thinner trailing edge and reduced manufacturing tolerances than is found in prior art segmental assemblies having forged airfoils with thick trailing edges and relatively large tolerance requirements. The particular design of the inventive blade also controls steam separation by control of the rate of change of convergence and turning angle. Steam velocity increases substantially continuously over the major extent of the suction surface of the blade to avoid flow separation.