Blade Vibration Monitoring Techniques in Turbomachinery

Blade vibration monitoring in turbomachinery is essential for ensuring the structural integrity, performance and safety of gas and steam turbines. Unchecked vibration can lead to fatigue cracks, blade deformation and catastrophic failure. Modern monitoring approaches fall into two broad categories: contact and non-contact methods. Contact techniques, such as strain gauges, offer high fidelity but are intrusive and limited by temperature and mounting constraints. Non-contact methods have become dominant, with blade tip timing (BTT) leading the field. BTT utilises a series of casing-mounted probes—optical, eddy-current, capacitive or microwave—to record the precise time of arrival of each blade tip. Deviations from uniform arrival times reveal vibration amplitudes and frequencies. Complementary measurements of tip clearance inform on blade deformation and aero-mechanical loading. Signal-processing advances address the inherent under-sampling of BTT data, employing circumferential Fourier fitting, sparse reconstruction and order analysis to recover synchronous and asynchronous vibration modes. Recent developments focus on handling variable rotor speeds, improving probe configurations and integrating deep-learning features for fault diagnosis. Together, these techniques enable on-line condition monitoring, reducing maintenance costs, extending component life and improving turbine efficiency across power generation and aero-engines.

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Blade Vibration Monitoring Techniques in Turbomachinery publication trend

The graph below shows the total number of articles in blade vibration monitoring techniques in turbomachinery across all publications each year (not limited to Nature Index journals).

Technical terms

Blade tip timing (BTT): A non-contact method that records the time at which blade tips pass sensors to infer vibration characteristics.

Time of arrival (ToA): The precise moment a blade tip is detected by a sensor, used to calculate vibration amplitude and frequency.

Engine order (EO): A multiple of the rotor speed representing specific vibration harmonics linked to blade dynamics.

Synchronous vibration: Blade oscillations that occur at integer multiples of the rotation speed, often indicative of resonance.

Tip clearance: The gap between blade tips and the casing, critical for aerodynamic efficiency and also used as a diagnostic signal.

References

1. Sparse Representation Based Frequency Detection and Uncertainty Reduction in Blade Tip Timing Measurement for Multi-Mode Blade Vibration Monitoring. Sensors (2017).
2. A Non-Uniformly Under-Sampled Blade Tip-Timing Signal Reconstruction Method for Blade Vibration Monitoring. Sensors (2015).
3. An Improved Circumferential Fourier Fit (CFF) Method for Blade Tip Timing Measurements. Applied Sciences (2020).
4. Reconstructed Order Analysis-Based Vibration Monitoring under Variable Rotation Speed by Using Multiple Blade Tip-Timing Sensors. Sensors (2018).
5. A Blade Tip Timing Method Based on a Microwave Sensor. Sensors (2017).