Tip timing measurements using fiber optic sensors

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Tip timing measurements using fiber optic sensors

SEDI-ATI offers fiber optic on/off probes consisting of bundles of optical fibers resistant to +600 °C in order to perform tip timing measurements during engine tests.

The challenge

Approaching multi-fiber optical links in a very high-temperature and highly vibrating turbine environment.

Major constraints

  • high-temperatures: > +600 °C
  • mechanical stress: chocs, vibrations, low bend radius

Aero-engine turbines put to the test

Turbine blades are critical parts of aeronautic engines. They are subjected to high mechanical stresses at very high temperatures. In the event of breakage, the integrity of the engine, or even of the aircraft, can be compromised.

What is tip-timing?

Tip-timing is involved in the qualification of engines and turboshafts. This technique enables to monitor the vibratory modes of turbine blades in operation and to detect possible blade deformations.

Measuring blades deformation using optical fibers

The campaign of tests consists in mounting optical sensors on the engine casing, in front of the blades, in order to measure their time of passage. The amplitude of vibration of each blade as it passes in front of the sensors can be deducted from the passage times of the blades and the speed of rotation.

Principle of the optical measurement

We use what we call “on/off probes” made out of bundles of fibers to perform the optical measurement that relies on the photon-emission/photon-reception principle.

An emitting fiber is used to illuminate the blades. The reflection on the blades is captured by the collecting fibers placed around the emitting fiber. The optical signals are then analyzed and interpreted using specific algorithms.

In aircraft engines, turbine blades are parts that operate at very high temperatures. SEDI-ATI designs quality optical probes that can withstand +600 °C.

SEDI-ATI solution

On/Off optical probes consisting in bundle assemblies of optical fibers resistant to +600 °C, and soldered at the tip.

Advantages of the SEDI-ATI solution

  • Our fiber assemblies withstand engine and turboshafts testing conditions.