Interpretation of Experimental and Theoretical Data for Prediction of Mode Shapes of Vibrating Turbocharger Blades

The blading in large turbochargers is subjected to vibration excitation originating from pulsations in the exhaust gas stream coupled with the blade pass frequencies. The amplitude of vibrations induced are a source of concern to design engineers as they can seriously affect the operation of the turbocharger. This paper discusses theoretical and experimental investigations aimed at identifying the natural frequencies and the associated mode shapes for a single turbocharger blade. Modal Analysis, Electronic Speckle Pattern Interferometry (ESPI), and Finite Element Analysis are all used in an attempt to categorize the modal patterns.