High-precision cone angle measurement of an aero-engine fuel nozzle based on a compound method

The geometry and its errors of an aero-engine nozzle have a direct impact on atomization level, fuel mixing and consumption, exhaust emission, and noise reduction. In order to overcome the low-accuracy deficiency of traditional detection techniques, in this work, a non-contact compound method is presented for the purpose of inspecting the key geometrical parameters of the nozzle (diameter of spray hole and its cone angle). We establish the data fusion model on the compound probe, which consists of a CCD camera and a laser holography sensor. An evaluation function is applied to determine the axis orientation of spray hole and implement the inspection operation. Cone-angle measurement can be skillfully transformed into the angle measurement of a pair of generatrices located at the plane, which passes through the axis of the cone surface thanks to the fusion model. The experimental results illustrate the feasibility of using the compound method. The testing repeatability errors of spray hole diameter and cone angle are 1.12 µm and 0.0113°, respectively.