Method for extracting inherent frequency difference between blades by single or uniformly distributed blade end timing sensor

Abstract

The invention discloses a method for extracting an inherent frequency difference value between blades by a single or uniformly distributed blade end timing sensor. The method comprises the following steps: acquiring the actual arrival time of a rotating blade by using a single blade end timing sensor or uniformly distributed blade end timing sensors; converting the difference between the theoretical arrival time and the actual arrival time into displacement data of the blade end according to the rotating speed and the blade length of the rotating blade; selecting displacement data of blade ends of two rotating blades with the same blade length at the same rotating speed; intercepting displacement data and respectively carrying out discrete Fourier transform, wherein the sampling frequency is approximate to the average rotating speed to obtain frequency spectrum data; and respectively extracting corresponding frequency remainders after aliasing the inherent frequencies of the two blades from the frequency spectrum data, and subtracting the two frequency remainders to obtain the inherent frequency difference between the two blades.

Description

technical field [0001] The invention belongs to the field of non-contact non-destructive detection of blades, in particular to a method for extracting natural frequency difference between blades by a single or evenly distributed blade end timing sensor. Background technique [0002] Rotor blades are key components of large-scale equipment such as gas turbines and aeroengines. They often rotate at high speed under high temperature and high pressure conditions, and are subjected to cyclic alternating loads and dynamic loads such as centrifugal force and aerodynamic force. vibration. Statistical data show that blade damage accidents account for about one-third of the total structural failures of gas turbines, so it is necessary to perform fault detection on rotor blades. However, the traditional contact blade vibration measurement method, such as the strain gauge measurement method, needs to be shut down and it is difficult to monitor the vibration of all blades, and the blade...

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Problems solved by technology

In the actual use of the tip timing measurement method, multiple tip timing sensors are often used to reduce the aliasing effect caused by undersampling, but the installation of multiple tip timing sensors in the actual limited space will cause greater trouble , and it also increases the measurement cost. Traditional methods, such as c

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