SYSTEM AND METHOD FOR MODIFYING MODAL VIBRATION ASSOCIATED WITH TURBINE

PROBLEM TO BE SOLVED: To provide a method improving design of an inner turbine shroud, as assistance for modification of vibration in the inner shroud. SOLUTION: The shroud assembly and the method for modifying one or more modal vibration frequencies of the inner shroud 700 of the shroud assembly in the turbine are described. The shroud assembly includes the inner shroud and an outer shroud. The inner shroud includes a first terminal end portion 708, a second terminal end portion 710 opposed to the first terminal end portion, an upper surface 704 and a lower surface 706 adjacent to a plurality of rotary turbine blades. The inner shroud includes rails 712a, 712b formed on the upper surface 704, extending between the first terminal end portion and the second terminal end portion and having an impingement cooling area 716 between them. The inner shroud includes one or more cross-member 718 formed on the upper surface in a direction crossing two or more of rails. The method for avoiding undesired mode excitation in the inner shroud is provided. COPYRIGHT: (C)2010,JPO&INPIT