The influence mechanism of blade crack on the acoustic characteristics of compressor

Abstract

A fault diagnosis method for blade cracks based on noise is proposed, and the mechanism of blade cracks on the rotor-stator interaction is studied. First, compressor noise is tested. The results show that blade cracks lead to significant changes in the blade passing frequency (1BPF). Thus, 1BPF is extracted for compressor blade crack identification. To investigate the influence mechanism of crack on 1BPF, the compressor characteristics are analyzed using the finite element method and dynamic mode decomposition. It is determined that the 1BPF of the compressor mainly originates from the trailing-edge potential flow field of the front-stage blade interfering with the rear-stage blade and is generated at the leading edge of the rear-stage stator blade. Because cracks affect 1BPF, and 1BPF is related to the trailing-edge potential flow field of the front-stage blade, the interaction mechanism between cracks and the trailing-edge potential flow field is studied. The flow field of an isolated blade is analyzed using finite element analysis, revealing that crack generation leads to enhanced fluctuations in the potential flow field of the blade, which in turn promote the rotor-stator interaction between the front and rear blades. This is finally reflected in changes in the 1BPF amplitude. Wind tunnel tests verify this theory. This paper analyzes the acoustic characteristics and influence mechanism of blade cracks on the compressor, providing a theoretical foundation for related research.