CASCADE STRUCTURE OF STEAM TURBINE

PURPOSE: To synchronize to vibration in the tangential direction, the axial direction and the torsional direction by moving mass distribution in each of blades in final blade cascades four pieces of which constitute a group. CONSTITUTION: Blades 10 constituting the final blade cascade are fundamentally made tapered vanes seen from a direction crossing with a blade vertical rotating surface. Additionally, a pair of connecting parts 12, 14 is provided on a point shown by cross sections F-F, B-B so as to install the blades 10 on adjoing blades. Hereby, movement of mass distribution is made on each of the cross sections. Consequently, each of the groups constituted of 4 pieces is synchronized against vibration in the tangential direction, the axial direction and the torsional direction on each of the groups constituted by 4 pieces. Consequently, each of the groups constituted of four pieces is synchronized to vibration in the tangenstial direction, the axial direction and the torsional direction. Consequently, characteristic frequency of the blade cascade can be clearly discriminated from harmonic vibration of turbine rotating speed.