Features of vibrations of moving blades in the last stages of a high-capacity steam turbine

Journal Article · Thu May 01 04:00:00 EDT 1975 · Therm. Eng. (USSR) (Engl. Transl.); (United States)

OSTI ID:7260835

Simin, O N

Increase in unit capacities of turbine units leads to increase in the length of blades, to a decrease in their natural frequencies and, as a result, to appearance of a great number of forms of vibrations in the zone being tuned out. To ensure reliable operation of these stages it is necessary to check the actual level of dynamic stresses occurring in the moving blades. Taking into consideration the difficulties in tests under full-scale conditions, a model experimental turbine was constructed of five stages to represent in a scale of 1:3 the flow section of the low pressure part of a high-capacity turbine; a water brake was used as the load. In testing, the equality of the main similarity criteria was maintained: M, Sh (Strouhal), and of the parameters of the working medium for the flow section. Similarity was not observed with respect to Reynolds numbers for the model and the full-scale machine. For the first three model stages, these numbers are within the zone of self-similarity; in the last two stages, owing to difference in Reynolds number, the profile losses (and disturbing forces associated with them) may prove to be higher in the model stages. With respect to conditions of similarity, the speed and the natural frequencies of the model blades are three times greater than in the full-scale machine. The design of the exhaust, of the lacing joining the blades (in all investigated stages two damping wires were fitted in each stage), relative sizes of clearances, as well as steam pressure at rated load in the model and in the full-scale turbines coincided.

• Research Organization: Leningrad Metal Working Plant
• OSTI ID: 7260835
• Journal Information: Therm. Eng. (USSR) (Engl. Transl.); (United States), Journal Name: Therm. Eng. (USSR) (Engl. Transl.); (United States) Vol. 22:5; ISSN THENA
• Country of Publication: United States
• Language: English

Related Subjects

20 FOSSIL-FUELED POWER PLANTS
200104* -- Fossil-Fueled Power Plants-- Components
BENCH-SCALE EXPERIMENTS
FUNCTIONAL MODELS
MECHANICAL VIBRATIONS
OPERATION
RELIABILITY
REYNOLDS NUMBER
STEAM TURBINES
STRESSES
TESTING
TURBINE BLADES
TURBINES
TURBOMACHINERY