Aerodynamic damping predictions for turbomachine blade rows using a three-dimensional time marching simulation

Gottfried, Dana A.; Fleeter, Sanford

doi:10.2514/6.1999-2810

Cited by 5 publications

(4 citation statements)

References 3 publications

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“…A similar method for estimating the damping of a turbomachinery blade undergoing multiple vibration modes was reported in Gottfried and Fleeter. 12 Using the above correlations, the decoupled approach estimated an averaged aerodynamic damping coefficient of 0.006. from the unsteady pressure signals.…”

Section: Fluid-structure Interaction (Fsi) and Modelling Approachmentioning

confidence: 99%

Influence of fluid-structure interaction modelling on the stress and fatigue life evaluation of a gas turbine blade

Ubulom

2020

Proceedings of the Institution of Mechanical Engineers, Part A:

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A computational method of fluid-structure coupling is implemented to predict the fatigue response of a high-pressure turbine blade. Two coupling levels, herein referred to as a “fully coupled” and “decoupled” methods are implemented to investigate the influence of multi-physics interaction on the 3 D stress state and fatigue response of a turbine blade. In the fully-coupled approach, the solutions of the fluid-flow and the solid-domain finite element problem are obtained concurrently, while in the decoupled approach, the independently computed aerodynamic forces are unilaterally transferred as boundary conditions in the subsequent finite element solution. In both cases, a three-dimensional unsteady stator-rotor aerodynamic configuration is modelled to depict a forced-vibration loading of high-cycle failure mode. Also analyzed is the low-cycle phenomenon which arises due to the mean stresses of the rotational load of the rotating turbine wheel. The coupling between the fluid and solid domains (fully-coupled approach) provides a form of damping which reduces the amplitude of fluctuation of the stress history, as opposed to the decoupled case with a resultant higher amplitude stress fluctuation. While the stress amplitude is higher in the decoupled case, the fatigue life-limiting condition is found to be significantly influenced by the higher mean stresses in the fully-coupled method. The differences between the two approaches are further explained considering three key fatigue parameters; mean stress, multiaxiality stress state and the stress ratio factors. The study shows that the influence of the coupling between the fluid and structures domain is an important factor in estimating the fatigue stress history.

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Section: Fluid-structure Interaction (Fsi) and Modelling Approachmentioning

confidence: 99%

Influence of fluid-structure interaction modelling on the stress and fatigue life evaluation of a gas turbine blade

Ubulom

2020

Proceedings of the Institution of Mechanical Engineers, Part A:

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“…The blade response in the flow case is due mainly to the influence of hourglass viscosity and that from the unsteady pressure. A similar method for estimating the damping of a turbomachinery blade undergoing multiple vibration modes in a time domain simulation of a fluid-structure interaction analysis was presented in Gottfried and Fleeter [9]. In using the above method, an estimated value of 5 Ubulom GTP-20-1395 the aerodynamic damping was obtained from the pressure field history on the blade surface.…”

Section: ) Fluid-structure Interaction Modellingmentioning

confidence: 99%

Application of Spectral Method for Vibration-Induced High-Cycle Fatigue Evaluation of an HP Turbine Blade

Ubulom

2020

Volume 10B: Structures and Dynamics

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A method of fluid-structure interaction coupling is implemented for a forced-response, vibration-induced fatigue life estimation of a high-pressure turbine blade. Two simulations approaches; a two-way (fully-coupled) and one-way (uncoupled) methods are implemented to investigate the influence of fluidsolid coupling on a turbine blade structural response. The fatigue analysis is performed using the frequency domain spectral moments estimated from the response power spectral density of the two simulation cases. The method is demonstrated in light of the time-domain method of the rainflow cycle counting method with mean stress correction. Correspondingly, the mean stress and multiaxiality effects are also accounted for in the frequency domain spectral approach. In the mean stress case, a multiplication coefficient is derived based on the Morrow equation, while the case of multiaxiality is based on a criterion which reduces the triaxial stress state to an equivalent uniaxial stress using the critical plane assumption. The analyses show that while the vibration-induced stress histories of both simulation approaches are stationary, they violate the assumption of normality of the frequency domain approaches. The stress history profile of both processes can be described as platykurtic with the distributions having less mass near its mean and in the tail region, as compared to a Gaussian distribution with an equal standard deviation. The fully-coupled method is right leaning with positive skewness while the uncoupled approach is left leaning with negative skewness. The directional orientation of the principal axes was also analyzed based on the Euler angle estimation. Although noticeable differences were found in the peak distribution of the normal stresses for both methods, the predicted Euler angle orientations were consistent in both cases, depicting a similar orientation of the critical plane during a crack initiation process. It is shown that the fatigue life estimation was conservative in the fully-coupled solution approach.

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“…Li and He [19] studied the aerodynamic damping of transonic fan, which pointed out that the aerodynamic damping could be considered to be linear under small oscillating amplitude. During the research on flutter and forced response of turbomachinery bladings, Gottfried and Fleeter [20] and Moffatt and He [21] concluded that blade vibration amplitude was less than 1 per cent of the blade chord, in which range the flow and unsteady aerodynamic force was linear well; thus, the non-linear influence could be ignored. The damping matrix diagonalization is realized by some engineering approximate approaches.…”

Section: Numerical Methodologymentioning

confidence: 99%

Flutter prediction in turbomachinery with energy method

Zhang

Wang

2011

Proceedings of the Institution of Mechanical Engineers, Part G:

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The study described in this article is the application of energy method for the prediction of flutter boundary and the effects of some parameters on aeroelastic stability in turbomachinery. The unsteady flow with multi-layer moving grid technique for blade oscillation was undergone for aerodynamic work with the blade passage being discretized using a background fixed H-grid and a body-fitted O-grid moving with the blade. Also, with the assumption of equivalent viscous damping, aerodynamic modal damping ratio was defined based on energy method. The numerical method, with mode shapes and nodal diameter numbers considered, was applied for a transonic compressor rotor stage for which measured flutter boundary on characteristic map was available. It was found that the calculated flutter boundary in the first bending blade mode agreed well with the measured one. Furthermore, it was concluded that the mode shapes and inter-blade phase angle were key parameters on aeroelasticity in turbomachinery and that the flutter instability was mainly induced by the co-action of shock wave and separated flow.

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Aerodynamic damping predictions for turbomachine blade rows using a three-dimensional time marching simulation

Cited by 5 publications

References 3 publications

Influence of fluid-structure interaction modelling on the stress and fatigue life evaluation of a gas turbine blade

Influence of fluid-structure interaction modelling on the stress and fatigue life evaluation of a gas turbine blade

Application of Spectral Method for Vibration-Induced High-Cycle Fatigue Evaluation of an HP Turbine Blade

Flutter prediction in turbomachinery with energy method

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