Turbine blade testing technique uses mechanical vibration and detection of frequency response to determine characteristics of each blade

摘要

Each blade is subjected to a mechanical excitation (16) and its acoustic response is detected by an acoustic detector (18) and a corresponding electrical signal generated. Using a Fast Fourier Transform (FFT) technique the frequency response of the blade is determined. The wheel is then accepted or rejected according to the distribution of frequencies obtained. The acoustic monitoring technique for a bladed turbine wheel operates whilst the wheel is in motion. Each blade is subjected to a mechanical excitation (16) and its acoustic response is detected by an acoustic detector (18) and a corresponding electrical signal generated. Using a Fast Fourier Transform (FFT) technique the frequency response of the blade is determined. The electrical signal and the associated frequency response are memorized and the characteristic frequencies of each blade are determined. The wheel is then accepted or rejected according to the distribution of frequencies obtained. Faults within the wheel may be determined by comparison of the response obtained with the responses obtained by known wheel faults.