Laser Vibrometry

The Institute for Thermal Turbomachinery and Machine Dynamics uses commercially available laser vibrometers for vibration analysis. The following image shows one such laser vibrometer being used in laboratory exercises for Master's students in Mechanical Engineering. Students are tasked with designing a turbine blade and using ANSYS Student to perform strength and vibration analyses at different speeds. These results are then compared with laser vibrometer measurements taken with the blade at rest and with broadband vibration excitation.

However, laser vibrometers can also be used to measure line-of-sight density fluctuations. The following figure illustrates how a blade profile was scanned across its surface. Once the frequency spectrum for each point on the surface has been displayed, the location of the laminar-turbulent transition and the zone of relaminarisation along the suction side of the turbine blade become clearly visible.