Campbell Testing

Accurately determine the natural frequencies and mode shapes of rotating turbine blade (bucket) rows.















Campbell Wheel Testing

Equipment Demonstration Produced by SimuTech Group in Rochester, NY

In this video, our engineers demonstrate strain gauge telemetry on a model rotating disk, designed to simulate vibration of actual turbine bladed discs.

This is the Campbell Wheel demonstration device, developed at Stress Technology, named in honor of Wilfred Campbell of General Electric, who pioneered the study of bladed disc vibrations.

A simulated bladed disc with cover band is driven by a DC motor capable of maintaining precise speed control.  A single air jet directs an axial force against the cover band of the rubber wheel. This air jet is analogous to the retractable steam jet typically used in telemetry testing of actual turbines.

To identify the speed mode frequencies and blade operational mode shapes, a flexible blade disc assembly can be simulated by a rubber wheel.

All the vibration characteristics of both systems are similar. However, the amplitudes of the rubber wheel vibration are considerably larger than the steel disc.  This is an advantage of the rubber wheel that permits visualization of the vibration. To demonstrate the strain gauge telemetry process, a strain gauge has been attached to the rubber wheel, and a transmitter assembly has been positioned on the rotor.

The sensor on the rotating disc produces an analog strain signal on the oscilloscope. The air jet exerts a force on the rotating disk at one location per revolution. This is analogous to the procedure used in full scale telemetry testing of turbines. At certain critical wheel speeds, bladed disc resonance will occur.



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