| Geared Turbofan Engine(GTF engine)is a new generation of bypass ratio turbofan engine.The engine fan rotor system includes a fan transmission system and a gear transmission system.The fan transmission system is a complicated rotor system.Mainly by the rectifying cone,the fan rotor,the fan shaft and the drive shaft and other components,in the normal operation of the engine a plurality of parts vibration coupled to each other,so that the analysis of such systems can not only be a single component for the study,but also The entire system was analyzed for vibration characteristics.In addition,due to the increase in the size of GTF fan blades,centrifugal force,aerodynamic force,and other unsteady excitation forces have a greater impact on the vibration of the fan drive system.Therefore,fluid-solid coupling vibration must also be performed according to the actual operating conditions of the GTF engine.Using finite element calculation and experimental verification to study the vibration characteristics of the fan drive system and the influence of fluid-solid coupling on the vibration characteristics.The following studies have been carried out:1.Three-dimensional modeling of the GTF engine fan drive system,by SolidWorks which has powerful 3D modeling capabilities for three-dimensional modeling and digital modification of the fan drive system components,assembly these parts through the relationship,Then,the load and boundary conditions of the fan drive system are analyzed and solid meshing is performed with ICEM,and the grid independence is verified.2.From the design point,the vibration characteristics of a GTF engine fan drive system and its components were analyzed,and the natural frequency and mode shapes of each stage were calculated.The effect of centrifugal load on the vibration mode of the modal frequency was considered.The Campbell diagram resonance analysis was performed for the system and the fan drive system.Considering the frequency doubled resonance and the double frequency harmonic resonance,the resonance point of the fan drive system was 6000 rpm and 12000 rpm.Its operating speed should avoid these two resonance speed points for the fan drive.Which provides a safety reference to the design of the system3.Based on the LMS modal vibration test,the natural frequencies and modal shapes of the fan shaft,drive shaft,fan blades,and fan rotor are verified.The modal frequency and vibration mode calculated by Workbench and the error of the test measurement are within an acceptable range.The accuracy and rationality of the finite element calculation provide a theoretical basis for analyzing the vibration characteristics of the GTF engine fan drive system.4.The fluid-structure coupling vibration characteristics of the fan blades are analyzed from the actual operating conditions of the GTF engine fan blades.According to the actual operating conditions of the engine,aerodynamic and centrifugal loads under a flight profile are studied for a certain GTF engine fan blade.It was found that the maximum stress deformation of the blade is in the middle of the blade.Therefore,in the design optimization,the manufacturing process in the middle of the blade should be strengthened to increase its rigidity and prevent engine accidents caused by vibration damage to the blade. |
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