Research Progress on Tip Clearance Measurement Technology for Aero-Engines: From Traditional Methods to Innovations in Laser Self-Mixing Interference​

Abstract

This paper systematically reviews the current development and research progress of tip clearance measurement technologies for turbine blades in aero-engines. Firstly, it defines tip clearance as the tiny radial distance between the tip of rotating blades and the inner wall of stator casings, emphasizing its critical role as a core parameter affecting engine aerodynamic efficiency, operational stability, and safety. By examining the principles and characteristics of traditional measurement techniques (e.g., capacitance method, eddy current method, and microwave method), the paper analyzes their limitations under extreme operating conditions such as high temperatures (>1000°C) and high rotational speeds (>15000 r/min), including poor anti-interference capability and insufficient precision (with errors typically exceeding 22μm). The focus is placed on elaborating the innovative breakthroughs of Laser Self-Mixing Interference (LSMI) technology: the three-mirror F-P cavity model enables dynamic synchronous measurement of rotational speed and clearance; the combined algorithm of wavelet denoising and windowed FFT reduces dynamic measurement error to 23μm and static error to 12μm; and the technology features non-contact operation, high-temperature resistance, and a compact structure. Applications in ground tests, airborne monitoring, and industrial machinery are discussed, highlighting its value in improving fuel efficiency (a 1% reduction cuts large airliner annual costs by $200,000), preventing blade rubbing, and supporting active control. Finally, the development trends of various technologies are summarized, providing theoretical references and technical support for the efficient and safe operation of aero-engines and their localized research and development.