The evaluation of profile errors of the leading and trailing edges of a thin-walled blade based on chord length deviation

The shape of leading and trailing edges (LTEs) of a thin-walled blade is one of the key parameters that influence the performance of an aero-engine, and an exact evaluation of the shape is the basis to ensure machining quality. When the chord length of a blade is deviated, the actual position of LTEs deviates from the theoretical curve. However, considering the problem that chord length deviation couples with profile errors of LTEs, the deviation is introduced into the evaluation of profile errors with the standard iterative closest point (ICP) algorithm, which results in an inexact evaluation and affects the performance of the aero-engine. To address this issue, a novel method that exactly evaluates profile errors of LTEs is proposed. Firstly, a data pre-transformation function is introduced into the standard ICP algorithm to separate the relationship between the chord length deviation and profile errors of LTEs. Secondly, a data preprocessing optimization model is established with the constraints of chord length tolerance and camber curve, which can ensure the trend of the blade and the continuity of measuring data. Thirdly, the model is solved by the particle swarm optimization (PSO) algorithm. Finally, this method is applied to the evaluation of profile errors of LTEs of an open blisk using simulation and experimental data to verify its availability. The results show that the proposed method can eliminate the adverse effect of chord length deviation and realize the exact evaluation of the profile errors of LTEs.