Flutter synchronization for turbo-compressor rotor blades

Initiation and development of flutter of axial turbo compressor rotor blades

“…Time dependence of rotation speed of a rotor by type BLISK (it is the abbreviations of Integrally Bladed Disk Design) of studied axial turbo compressor is given in [3]. In the BLISK the blades oscillations are weakly structurally and constructionally damped compared to a disk with inserted blades (having a natu ral dissipation in the lock), and the weakly damp lightens an ini tiation of a flutter.…”

“…In the BLISK the blades oscillations are weakly structurally and constructionally damped compared to a disk with inserted blades (having a natu ral dissipation in the lock), and the weakly damp lightens an ini tiation of a flutter. The work [3] shows the tensometric records of oscillation of the blades 3, 5, and 14, carried out in the antin ode of flexural mode with frequency f B ≈ 81 Hz (the sampling frequency is about ≈20 kHz). In the time range t = 4-20 s the torsion modes of the blade are initially excited with a frequency f T ≈ 178 Hz close in this time interval to the harmonic 3f R of rotor rotation speed, transmitted to the blades by aerodynamic traces in the airflow.…”

“…With increases of rotor rotation speed, the torsional mode falls out from resonance at the frequency f T , and a flutter comes at lower frequency f B ≈ 81 Hz of blades flexural mode. The work [3] shows the sync process of the flexural oscil lations of blades 3, 5, and 14 of first rotor stage under a flutter. The spectral parameters of the oscillations records are deter mined by the Prony method.…”

Bifurcation of resonance during flutter of the blades of a turbocompressor rotor

“…The fea ture of the development of flutter at the rotational fre quency of the blades is its decrement (Fig. 4) [3]. Stabilization of the rotational frequency of the tur bocompressor rotor does not interrupt the develop ment of the flutter of the blade cascade.…”

“…The phase shift between vibrations of neighboring rotor blades determines aerodynamic damping at the torsional or bending blade frequency, which depends on parameters m and N b . In the range of phase shift from 0 to 180°, i.e., with the number of the most valu able diameters m = 1, 2, and 3, the aerodynamic damping factor (logarithmic decrement) δ is positive and circular modes of collective vibrations of the blades are unstable [3]. Frequency of the mode of pulsations of the pressure of the air flow with m node diameters is associated with the frequencies of the tor ( ) π σ = = ± ± ± − 2 , 0, 1, 2, ..., 1 , The rotating separation is the localized separation (and/or rotation) cell of the flow which rotates after the rotor with a frequency on the order from 30 to 70% of rotation frequency of the rotor.…”