Bidirectional Measurement Method for Turbine-Based Combined Cycle Engine Based on System Errors Decoupling

The accuracy of rotor profile measurement is the foundation for achieving high-precision assembly of turbine-based combined cycle (TBCC) engine. Conventional instruments are hardware-limited to micrometer-level accuracy due to multisubsystem error coupling. Existing methods focus on sensor resolution improvement, lacking novel measurement models and bidirectional error separation techniques for cost-effective high-precision measurement. This article employs an equivalent projection method to comprehensively analyze the coupling relationship of multisource system errors in bidirectional measurement of the rotor and simultaneously accounts for the influence of errors on the actual sampling angle. A new bidirectional profile measurement model for the rotor was established based on the positional errors caused by the rotor deviating from the axis of rotation, sensor system errors, and guide rail spatial errors. Finally, by performing bidirectional parameter estimation on the measurement model, the bidirectional error separation of the section and loop profile data is achieved. The results show that compared with the mainstream method, the perpendicularity measurement error of the axial profile of our method is reduced by 6% and the radial profile coaxiality measurement error is reduced by 25%. By optimizing the measurement model, we have improved the measurement accuracy and demonstrated the effectiveness of our method. This method provides a reliable theoretical basis for precision low-cost measurement of next-generation high-end rotary equipment.