Optical tip timing method based on tip surface microstructure

Abstract

The invention relates to the field of optical tip timing methods, and specifically relates to an optical tip timing method based on a tip surface microstructure. A mechanical processing means is usedto enable the tip surface to form a micro-surface with a characteristic structure along a vertical direction of the movement direction of a tip, and the scattered light intensity of the surface of themicrostructure is used to carry out time discrimination. The method comprises the following steps: step (1), constructing a tip surface characteristic structure; step (2), performing tip surface parameter calibration; step (3), acquiring a tip microstructure scattered light signal; and step (4), enabling the tip to achieve time demodulation. The optical tip timing method based on the tip surfacemicrostructure provided by the invention has the following advantages: different from other optical tip timing methods that threshold trigger is performed by using a rising edge or a falling edge of asignal, the method of the invention uses the phase of the signal to perform time discrimination, which is not affected by the change of the amplitude of the signal, thus errors introduced by the random jitter of the signal caused by the rough surface of the tip, the tip erosion, the gap change, the light source jitter and the like can be effectively reduced, and the timing accuracy of the tip andthe stability of a system are greatly improved.

Description

technical field [0001] The invention relates to the field of optical blade tip timing methods, in particular to an optical blade tip timing method based on the microstructure of the blade tip surface. Background technique [0002] Aeroengines are an important part of the propulsion system that provides mechanical power for aircraft. It is sophisticated and complex, and directly affects the flexibility, endurance, flight speed, rated load, and stability of the aircraft. It is a manifestation of the strength of a country. As the core part of the aero-engine structure, the blade determines the important performance of the engine such as working efficiency, stability, reliability and durability, and it is of great significance to ensure its working efficiency and safe rotation. During the high-speed rotation of the blade, under the influence of the harsh environment of high temperature, high pressure and heavy load, it will bear its own centrifugal force, air flow force, mechani...

AI Technical Summary

Problems solved by technology

There are two main factors that affect the accuracy of the blade tip timing system: one is that during the high-speed rotation of the blade, due to thermal expansion mismatch between the rotor and the stator and changes in centrifugal force, the blade tip clearance changes, and the change of the tip clearance will lead to receiving The intensity and shape of the optical signal change, resulting in a large error in the determination of the arrival time of the blade; the second is that with the erosion of the harsh and complex environment, the reflection performance of the blade end surface is constantly changing, which has a great impact on the timing accuracy of the system. big impact

[0004] In the traditional blade vibration measurement system based on the blade tip timing principle, the rising edge of the pulse signal is used as the arrival time of the blade. This processing algorithm does not take into account the influence of factors such as blade tip clearance changes, resulting in the extracted The arrival time is not accurate, which eventually leads to errors in the measured blade vibration parameters, which reduces the accuracy of the entire tip timing measurement system

Later, researchers successively proposed the constant-ratio timing time identification method using half of the peak value as the trigger voltage, and the method of taking the middle time between the rising edge time and the falling edge time of the pulse signal as the arrival time of the blade, etc., but in the actual measurement environment , the optical signal received by the blade tip sensor will fluctuate randomly with factors such as gap change, blade tip erosion and other factors, triggering and timing the optical signal with random jitter to measure the arrival time of the blade will bring inevitable errors

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