Natural Frequency and Resonance Study of FGM Turbo-Machinery Blade Using Campbell Diagram

Abstract

Abstract Turbo machinery rotating blades are a vital component of aero-engines for transferring the energy of gas flow to kinetic energy. Rotating turbo-machinery blades are prone to fail under working fields with high temperature, high speed, high pressure and resonance of blades with prime engine. Vibration of the turbo-machinery blades need to be studied carefully for safe and reliable operation of the engine. Thermal barrier coatings (TBC) layers are used to protect the blade metal at higher operating temperature though these can be plagued due to phase instability, thermal instability and adherence problems. TBCs also tend to spall due to thermal expansion mismatch with the super alloy substrate or because of erosion/impact caused by particles in the high-velocity combustion gases. Functionally graded materials (FGMs) are a relatively new class of materials that can solve these problems in high-temperature environments and can be considered as potential material for making gas turbine blades. Unlike composite materials the functionally graded materials (FGMs) are free from delamination and debonding and have the ability to withstand high temperature without TBC coatings. In this present study natural frequency of the FGM turbine blade for various rotational speeds during actual operation is determined using finite element technique. As the aero-engine is complex in nature therefore harmonic resonance can always occur in the aero-engine system and it is difficult to determine the natural frequency at varying speed during actual operation. The chances of failure of the blade also increase because of harmonic resonance. Hence, the resonance property is required to investigate of the FGM blade in details. Various rotational speed and operating temperature is considered to determine the natural frequencies of the blade. The resonance studies for each case are performed using the Campbell diagram. Resonance margin is calculated for each case and safe operating speed is determined. This study could serve as ready reference for safe operation of turbo-machinery engine considering FGM blade for specific range of engine speed.