A High-Precision Measurement Method for Blade Tip Vibration and Clearance Based on Capacitive Sensor

In the operational monitoring of turbomachinery, the assessment and diagnosis of blade conditions, including tip vibration and tip clearance, are essential to ensuring equipment safety. Large turbine units often require simultaneous measurement of blade tip vibration and clearance; however, traditional fiber optic testing methods do not fully meet this requirement. This paper proposes a high-precision measurement method for blade tip vibration and clearance based on capacitive sensors, with the innovation of introducing a Gaussian distribution model for nonlinear fitting of blade dynamic signals for the first time. By establishing a relative motion model between the capacitive sensor and the blade, and applying the Continuous Gaussian Fitting (CGF) algorithm, environmental noise interference is significantly reduced, and feature detection accuracy is improved. Experimental results show that, compared to the traditional Threshold Value Method (TVM), the accuracy of blade clearance and vibration calculations under constant-speed conditions is 1.94 times and 4.15 times higher, respectively. This method provides a new noise-resistant solution for blade monitoring under complex operating conditions.