Motion Amplification - Fan Blade Cracking - LASER TACH

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We are getting some fantastic results with the latest cutting edge technology from RDI Technologies Inc. the LASER TACH. Following on from a trial run at one of our regular power plants in the UK. We were asked to model the motion of some ACC cooling fan blades during operation at a site where they were experiencing a significant number of cracks near the root of the blades.

The site did not know if the cracks were due to a transient event, ie gusts of wind or if it there is some vibration motion on the blades leading to cyclic fatigue failures. A different designed fan was installed on one unit which we used as a comparison to the old blade design where the cracks had been occurring.

The LASER TACH works by syncing the IRIS M Motion Amplification Camera via a pulse from a tachometer. ( 1XRPM of the fan in this case). This results in freezing the rotating component on the image, very similar to a strobe light. The big difference is then we can collect many images in this case 200 revolutions and create an MA video. We can then filter to non-synchronous individual frequencies of interest on the rotating component and motion amplify to visualize and measure the motion. Quite amazing really.

As you can see from the footage of the old fan design, significant flexing motion over a shot distance is occurring constantly in the exact location of where the cracking has been occurring. In contrast the new fan design shows much less motion with a limited amount of flexing near the shaft next to the fan hub. The Motion Amplification data clearly shows that the problem is present all the time and is not a transient event caused by gusts of wind. The site is now in the process of replacing the old fan design with the new design to improve reliability.

Significant savings have been made as this testing has removed the need for external wind baffles to counteract the transient wind gusts.

#motionamplification #vibrationanalysis #conditionmonitoring #irism #reliability