Apparatus for indicating the vibration of turboengine rotor blades

1,143,339. Detecting vibration in turbines, electrically. TSENTRALNY ORDENA LENINA INSTITUT AVIATSIONNOGO MOTOROSTROENIA IM. P.I. BARANOVA. Feb.5, 1968, No.5638/68. Heading G1N. Apparatus for indicating the vibration of the outer ends of turbine rotor blades relative to the blade roots, comprises a pulse transmitter 1 Fig. 1 fixed to a stationary part opposite to marks 9 (e. g. pins or recesses) on a disc 10 on the rotor shaft producing pulses 20 Fig. 5 as the marks 9 pass it. The angular pitch of the marks corresponds to that of the blades. A transmitter 2 is fixed to a stationary part adjacent the radially outer ends of the blades, is angularly displaced from transmitter 1 by an angle # 1 , and produces pulses 21 as the blade ends pass it. The angle of displacement of the transmitters is representative of a predetermined vibration amplitude to be indicated. Pulses 20 are shaped in a unit 3 to produce pulses 22. Pulses 21 are shaped in a unit 5 stretched in a unit 6 to produce pulses 23. Both sets of pulses are fed to a gate 4. Due to the initial displacement angle between transmitters, in the absence of vibration the pulses 20, 21 do not coincide and there is no output from gate 4. When vibration occurs the pulses from transmitter 2 are phase modulated and if the vibration amplitude becomes equal to or exceeds a pre-set value for one blade the phase displaced pulses 24 from transmitter 2 will either coincide with or lead the pulses 25 from transmitter 1, and pulses 26 27, will sometimes coincide, so that gate 4 will open producing pulses 28. The output of the gate is fed to a neon warning lamp 7 and to a recorder 8. Alternatively the transmitters may be positioned to sense: - interacting blade vibrations as illustrated in Fig. 2 (not shown); torsional vibrations of blade Fig. 3 (not shown); a plurality of vibration amplitude levels Fig. 4 (not shown). The transmitters may be capacitive or inductive.