Study on the method of avoiding resonance for double-walled single-crystal turbine blades based on crystallographic orientation design: A technique for solving macroscopic vibration problems from a microscopic scale

Third-order torsional vibration frequency dispersion and the corresponding resonance issues that occur in the new double-walled single crystal turbine blades present a challenging engineering design issue. Therefore, a breakthrough in the crystallographic orientation design technology is crucial to achieve frequency adjustment and resonance avoidance. In this study, based on the grain microstructure characteristics, the method of defining the crystal orientation deviation angle of single-crystal blades was proposed for the first time, and the decoupling model of the grain microstructure attitude angles was established accordingly. Subsequently, the experiments were conducted to validate the grain-attitude dependent vibration theory and the orientation research methodology. Then, numerical simulation tests of the orientation-dependent vibration characteristics were conducted to investigate the influence rule of the primary orientation deviation angle and quadrant angle, the secondary orientation rotation angle, and the coupled orientation deviation angle on vibration frequency. Finally, the design schemes were developed, and compared in terms of their effectiveness in achieving frequency adjustment and resonance avoidance. The results showed that Case 7 not only considerably reduced the frequency dispersion, but also achieved the safety-margin requirement for resonance. Therefore, the proposed orientation design method is effective in solving macroscale resonance issues from a microscale perspective in single-crystal blades, and is expected to provide support for the engineering design of turbine blades.