A Study of Nonlinear Vibrations in a Frictionally Damped Turbine Bladed Disk With Comprehensive Modeling of Aerodynamic Effects

Abstract

A new effective method for comprehensive modeling of gas flow effects on vibration of nonlinear vibration of bladed disks has been developed for a case when the effect of the gas flow on the mode shapes is significant. The method separates completely the structural dynamics calculations from the significantly more computationally expensive computational fluid dynamics (CFD) calculations while providing the high accuracy of modeling for aerodynamic effects. A comprehensive analysis of the forced response using the new method has been performed for a realistic turbine bladed disk with root-disk joints, tip, and under-platform dampers. The full chain of aerodynamic and structural calculations are performed: (i) determination of boundary conditions for CFD, (ii) CFD analysis, (iii) calculation of the aerodynamic characteristics required by the new method, and (iv) nonlinear forced response analysis using the modal aerodynamic influence matrix (MAIM). The efficiency of the friction damping devices has been studied and compared for several resonance frequencies and engine orders. Advantages of the method for aerodynamic effect modeling have been demonstrated.

Aeromechanical Modeling of Rotating Fan Blades to Investigate High-Cycle and Low-Cycle Fatigue Interaction

“…The circumferential wavelength is usually much longer than the blade chord, therefore there is no direct periodicity between blade passages, but a phase difference, described by the interblade phase angle (IBPA) [27], Although the single blade passage will compromise accuracy in terms of aero dynamic performance and aerodynamic damping calculations, this method is still useful because it isolates the effect from the IGV wake passings. There is a tradeoff between improving the fidelity of the coupling effect or improving the fidelity of the numerical model by accounting for annulus and blade row effects [28], because it is infeasible to perform a fully coupled analysis on a full annulus and multiple blade rows. In the current study, the choice was made to model the fully coupled effect instead of the increased size of the numerical model, which can be considered for future work.…”

Dynamic Modeling and Projection-Based Reduction Methods for Bladed Disks With Nonlinear Frictional and Intermittent Contact Interfaces

“…While studying the dynamics of the blisk computationally, an equivalent dynamic problem is considered for convenience. The problem is analyzed from the perspective of the rotating frame of reference, where the blisk is stationary and the pressure wave is rotating [4,103,104]. Such a rotating wavefront, called a traveling wave excitation, is conceptually illustrated in Fig.…”

A Nonlinear vibration analysis of forced response for a bladed-disk with dry friction dampers

“…34 Furthermore, the method was generalization in finite element analysis for high-fidelity bladed-disk. 35,36 In realistic design practice, there is usually a need to choose sets of parameters of interest that can provide minimum forced response or satisfy other requirements. Moreover, all the parameters of the bladeddisk design problem are subjected to some variations due to operating condition changes.…”