ROTOR SYSTEM MATHEMATICAL MODEL SUBSTRUCTURE-BASED REDUCTION AND UPDATING USING EXPERIMENTAL MODAL ANALYSIS

Modeling of rotor dynamics is one of the most important parts of gas turbine engine creation process. But the need to understand the system response to design predictable, low maintenance, cost-effective, and optimal systems has driven rotor dynamics to large-order complex rotor system models. These models contain more intricate geometric complexities, bearings, seals, and attached components such as disks, blades, fans, and couplings. All this makes vibration processes more complicated and so they require more calculation resources. That makes such iterative procedures as model updating and optimization difficult. Possible solution for this problem is substructuring. Partitioning of the model to substructures opens up a possibility to verify and update parts of the model independently using modern modal analysis experimental techniques like 3D scanning vibrometry. And then they can be condensed using reduction methods to simplify the whole model. This work demonstrates the possible way of rotor system model updating based on experimental modal analysis via 3D scanning vibrometry and reduction using CMS method. Demonstration of the method is made on a special rotor test rig. The quality of updating and reduction is evaluated by comparing of critical speeds obtained numerically and experimentally. The comparison shows that proposed method is adequate for rotor system model creation and simplification but for constructions with a lot of connections updating procedure should be improved.