A Metrological Method of the Profile Camber Angle of Aeroengine Blades

The profile camber angle is a key influence parameter on the aerodynamic performance of blades, the measurement of the profile camber angle is of great significance to the optimization design and the quality control for blades. In order to solve the problems in adaptability and accuracy of existing measurement methods, a form-free high-precision metrological method of the profile camber angle of blades is proposed in the study, and the theoretical model, the measuring principle and the key technologies of the method are discussed in detail. The coordinate data of the blade profile are measured accurately in form-free mode with a high-precision laser probe system based on the depth control of field, and the measuring profile and the mean camber line are extracted based on the methodology of high-order polynomial least squares fitting. Thus, the high-precision measurement of the profile camber angle of blades is achieved. The research results show that the comprehensive accuracy of coordinate measurement reaches 10 μm level, and the measurement uncertainty of the profile camber angle is less than 0.15°, thus can meet the measuring requirements of aero-turbine blades with first precision grade. The method presented in the paper has advantages of form-free, high-precision and simple algorithm, and can solve the problems of high-precision measurement and evaluation for the profile camber angle of aeroengine blades primely.