Study on Propagation Depth of Ultrasonic Longitudinal Critically Refracted (LCR) Wave.

Yongmeng Liu,Xiaoming Wang,Chuanzhi Sun,Enxiao Liu,Jiubin Tan,Yuanlin Chen

doi:10.3390/s20195724

Abstract

The accurate measurement of stress at different depths in the end face of a high-pressure compressor rotor is particularly important, as it is directly related to the assembly quality and overall performance of aero-engines. The ultrasonic longitudinal critically refracted (LCR) wave is sensitive to stress and can measure stress at different depths, which has a prominent advantage in stress non-destructive measurements. In order to accurately characterize the propagation depth of LCR waves and improve the spatial resolution of stress measurement, a finite element model suitable for the study of LCR wave propagation depths was established based on a wave equation and Snell law, and the generation and propagation process of LCR waves are analyzed. By analyzing the blocking effect of grooves with different depths on the wave, the propagation depth of the LCR wave at seven specific frequencies was determined in turn. On this basis, the LCR wave propagation depth model is established, and the effects of wedge materials, piezoelectric element diameters, and excitation voltages on the propagation depth of LCR waves are discussed. This study is of great significance to improve the spatial resolution of stress measurements at different depths in the end face of the aero-engine rotor.

Highlights

The core engine system is composed of multi-stage rotors
The results show that the According to the calculation formula between wavelength and frequency, the propagation depth propagation depth of the longitudinal critically refracted (LCR) wave is 1 mm when the frequency is 5 MHz
The results show that the propagation depth of the accuracy of LCR wave propagation depth

Summary

Introduction

The core engine system is composed of multi-stage rotors. The superposition of residual stress and assembly stress makes the distribution of stress fields at different positions and depths of the rotor components more complicated. The assembly quality of rotors at all levels has a great impact on the performance of aero-engines [1,2,3]. In the case of high-speed rotation, the imbalance response caused by the coaxiality error will be amplified, resulting in engine vibration and causing friction between the blade and the casing [4]. It is necessary to realize the precise control of stress at different depths in the rotor end face through accurate measurements [7,8,9] and improve the uniformity of the stress field distribution to reduce the coaxiality error of the assembled rotor, so as to improve the safety and reliability of the aero-engine

Methods

Results

Conclusion