Flutter Generation and Control Using Mistuning in a Turbine Rotating Rig

Corral, Roque; Beloki, Josu; Calza, Paolo; Elliott, Robert C.

doi:10.2514/1.j056943

Cited by 30 publications

(27 citation statements)

References 34 publications

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“…The linear aerodynamic force coefficients (aerodamping and fre-quency correction) are taken from the FUTURE LPT rotor (see Figure 2), and the friction damping parameters are adjusted to reproduce the actual blade displacements measured in the experiment at the nominal rotation speed. The blade displacements reported in [22] correspond to different air densities (different mass-flow), which, within the operating range of the experiment, can be considered to be approximately proportional to the aerodynamic damping (see [22]). Figure 7 shows the resulting data fitting: solid dots correspond to the experimental blade displacement for different aerodynamic damping values from [22], and the empty circles are the mass-spring model tuned results.…”

Section: Mass-spring Model Resultsmentioning

confidence: 99%

“…The experimental results were obtained as part of the European project FUTURE whose main goal was to improve the aeromechanical analysis and design of lightweight blades [21]. Here, only a concise description of the experimental set-up is presented; for a more detailed explanation see [22,23].…”

Section: Experimental Modelmentioning

confidence: 99%

“…The number of blades of the LPT rotor was N = 146, and it was designed in order to have a first modal family of blade dominated flap modes with very similar frequencies (see Figure 1), and a quite low reduced frequency k ∼ 0.075. More details on the aeromechanic characteristics of the test case can be found in [22].…”

Section: Experimental Modelmentioning

confidence: 99%

“…(see [22]). The Olofsson model is a well established model to describe microslip friction effects between dry surfaces undergoing oscillating motion [24], and is used for the nonlinear friction force in equations (1).…”

Section: V10at24a018-4mentioning

confidence: 99%

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Mistuning Effects on the Nonlinear Friction Saturation of Flutter Vibration Amplitude

Martel

Rodríguez

2020

Volume 10A: Structures and Dynamics

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The blade vibration level of an aerodynamically unstable rotor is a quantity of crucial importance to correctly estimate the blade fatigue life. This amplitude is the result of the balance between the energy pumped into the blades by the gas flow, and the nonlinear dissipation at the blade-disk contact interfaces. In a tuned configuration, the blade displacements can be described as a travelling wave consisting of one fundamental nodal diameter and frequency and its higher harmonics, and the problem can be reduced to the computation of a time periodic solution in just one sector. This simplification is no longer valid for a mistuned bladed disk. The resulting nonlinear vibration of the mistuned system is a combination of several travelling waves with different number of nodal diameters, coupled through mistuning. In this case, the complete bladed disk has to be considered, which requires an extremely high computational cost, and, for this reason, reduced order models (ROM) are required to analyze this situation. In this work, we use a 3 DOF/sector mass-spring system to describe the nonlinear friction saturation of the flutter vibration amplitude of a realistic mistuned bladed disk. The convergence of the solution of the mass-spring system is still quite slow because of the presence of many unstable modes with very similar growth rates. In order to speed-up the simulations a simpler asymptotic ROM is derived from the mass-spring model, which allows for much faster integration times. The simulations of the asymptotic ROM are compared with the measurements obtained in the European project FUTURE, where an aerodynamically unstable LPT rotor was tested with different intentional mistuning patterns.

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Section: Mass-spring Model Resultsmentioning

confidence: 99%

Section: Experimental Modelmentioning

confidence: 99%

Section: Experimental Modelmentioning

confidence: 99%

Section: V10at24a018-4mentioning

confidence: 99%

See 2 more Smart Citations

Mistuning Effects on the Nonlinear Friction Saturation of Flutter Vibration Amplitude

Martel

Rodríguez

2020

Volume 10A: Structures and Dynamics

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“…It is important to point out that the vibration amplitude reached when two forced responses are present in the problem is higher than that obtained in the interaction between flutter and forced response. As mentioned, the friction of the model was calibrated with data from FUTURE flutter tests (Corral et al, 2018), and, if the same forcing amplitudes than in the previous section were used, the resulting displacements would grow into the macroslip regime close to the resonance peaks. To remain into the microslip regime throughout all the simulations, the excitation levels of both forcings have been reduced.…”

Section: Two Combined External Forcingsmentioning

confidence: 99%

Nonlinear mode interaction effects in the vibration of bladed-disks

Rodríguez¹,

Martel²

2020

Proceedings of Global Power &Amp; Propulsion Society

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Nonlinear mode interaction caused by friction at blade-root attachments is a common phenomenon in current bladeddisk configurations. However, it is still far from been completely understood, and the application of simple linear superposition can lead to an overestimation of the system vibrational response. In this work, nonlinear mode interaction is analyzed using a simplified mass-spring model with a microslip friction model. The parameters of the model are set using data from actual experimental results from a realistic bladed-disk, which are rarely available. Two different configurations are considered. The interaction of the synchronous response of the system due to harmonic excitation with a nonsynchronous aerodynamically unstable mode, and the interaction of two synchronous harmonic excitations with similar frequencies and different engine orders.

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Simplification of the forced response of mistuned bladed disks using multiple scales techniques

Martín

Martel

2021

Nonlinear Dyn

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Mistiming can produce a considerable increase of the vibratory forced response of the blades compared with that of the tuned bladed disk. This situation can lead to high cycle fatigue failure, and, therefore, it is of crucial importance for the prediction of the safe operation limit of the bladed disk. Nonlinear friction forces determine the final vibration amplitude of the blades, and, because of mistuning, the complete bladed disk has to be considered, increasing considerably the difficulty of the problem. For this reason, we consider the application of asymptotic multiple scale techniques to derive simplified models that give the final vibration states at a very low CPU cost. This asymptotic method is based on the idea that all significant effects (forcing, nonlinear friction damping, and mistuning) produce, in most practical situations, just small corrections of the tuned blade elastic oscillation. These small effects develop in a much longer time scale than that associated with the natural elastic frequency of the tuned system. The reduced models produced by this asymptotic methodology retain only the slow time dynamics, filtering out the fast scale oscillation. In this paper, the bladed disk is described using a mass-spring system with nonlinear friction and with an external forcing acting on a blade-dominated modal family where all modes have very similar vibration frequencies. The derivation of the asymptotic model from the mass-spring system is explained in detail, and validated against the results from the original mass-spring model.

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Flutter Generation and Control Using Mistuning in a Turbine Rotating Rig

Cited by 30 publications

References 34 publications

Mistuning Effects on the Nonlinear Friction Saturation of Flutter Vibration Amplitude

Mistuning Effects on the Nonlinear Friction Saturation of Flutter Vibration Amplitude

Nonlinear mode interaction effects in the vibration of bladed-disks

Simplification of the forced response of mistuned bladed disks using multiple scales techniques

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