Blade Forced Response Prediction for Industrial Gas Turbines

A decoupled aeromechanical system based on an advanced frequency-domain computational fluid dynamics finite element to CFD solver with fully nonlinear capability is presented that allows resonant vibration predictions to be routinely performed during the design process. A new energy method is presented that solves the blade response without the knowledge of original modeshape scales. A robust finite element CFD mesh interface has been developed for industrial use that can accurately deal with differences in mesh geometry, low mesh density, and high modeshape gradients. The capability of the baseline CFD solver for blade row interaction flow prediction is further validated against the von Karman Institute transonic turbine stage. A forced response analysis is carried out on the NASA Rotor 67 transonic fan for demonstration purposes. The system is evaluated for a challenging industrial study of the ALSTOM three-stage transonic test compressor, where the forced response predictions of three crossing points on the Campbell diagram compare well with strain gauge test data. An investigation into aerodynamic damping of the first 10 modes shows a high dependency on modeshape.