165 / 2021-03-31 16:22:38

Research on the Influence of Crack Parameters on the Vibration Characteristics of Gas Turbine Compressor Blades

compressor blade; blade crack; modal analysis; finite element method

Machine condition monitoring and fault diagnosis

As one of the core components of the gas turbine compressor, the blades are prone to cracks and even breakages when working in harsh environments such as high pressure, high speed, and alternating heavy loads, which may lead to blade failure. The generation and propagation of cracks will change the natural vibration characteristics of blades. Therefore, it is necessary to research the influence of different types of crack faults on the natural vibration characteristics of blades, which can provide a theoretical reference for the blade crack fault diagnosis. Firstly, the finite element model of the healthy gas turbine compressor blade was established, and the modal parameters were analysed; secondly, in order to revise the finite element model, the blade modal experiment platform was built to carry out the modal experiment of the healthy blade based on the moving hammer method, and the influence of different sensor installation methods on the modal test results was analysed; finally, based on the revised finite element model, the modal parameters of the blade with different types of crack faults were analysed, and the mapping relationship between the crack faults and the natural vibration characteristics of the blade was established. The results show that crack type variation would affect the natural vibration characteristics of the blade, which will lead to modal coupling and modal shape switching characteristics. As a result, the same order vibration mode of blade has different mode shapes at different crack positions and shapes. The results of this paper may serve as a theoretical basis for the diagnosis of compressor blade crack faults based on vibration characteristics.