National Repository of Grey Literature 2 records found  Search took 0.01 seconds. 
Running excitation of blades bunches
Půst, Ladislav ; Pešek, Luděk
Application of additional damping elements or friction connection into blades’ shroud very effectively restricts undesirable vibrations of turbine blades vibrations. The previous investigation of dynamic properties of five-blades-model connected either by a rubber element, by direct Coulomb friction contact or by modified Coulomb friction contact showed very positive results. However, only one type of excitation force vector with one harmonic force acting on the first mass has been used in these studies. Proposed paper will be oriented on the response of the same fiveblades- bunch provided again by means of the same types of dry friction damping connections, but excited by running harmonic force. This type of excitation corresponds better to the real excitation in the steam or gas turbine. Influence of friction forces type, running velocity (depends on ratio of stator and rotor blades numbers), amplitudes of excitation forces, etc. will be analysed and presented.
Vibrations of blades bunches
Půst, Ladislav ; Pešek, Luděk
Paper describes a mathematical model for analysing the dynamic characteristics of five-blades bunch with different damping connections among individual blades. The connections of blades by means of special rubber elements either with the fixed contact with neighbouring blades or with one-sided slip is presented. Systems with dry friction connections among blades by means of direct contacts or by inserted dry friction elements are described as well. As an example of analysis results, response curves of five-blades-bunch excited on first blade at different dry friction force in the first bending resonance is shown. Elaborated analysis create the basic theoretical background for evaluation of measurement on experimental bladed disk set in the laboratory of Institute of Thermomechanics of ASCR and it is also applied for evaluation of effectiveness of methods for suppression of forced vibration of blades.

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