The inner-cone angle measurement of aero-engine nozzle based on conoscopic holography

The geometry of aero-engine nozzle has a significant impact on its working performance. In this work, the conoscopic holography is employed to measure the inner-cone angle of aero-engine nozzle in a noncontact way. For such purpose, a five-axis coordinate measuring machine, the experimental platform, is built. Its measuring mathematic model is established afterwards according to multi-body kinematics. The objective function of least square fitting on conic surface is defined in terms of parameterized vector of cone, and Levenberg-Marquardt algorithm is used for solving its unknown geometric parameters. Finally, the experimental results demonstrate that the adopted method in this work is feasible and high-precision. The measuring repetitive error of conic angle is within 0.0019°.