Gas Turbine Blade Damper Optimization Methodology

Giridhar, Rohith; Ramaiah, P. Venkata; Krishnaiah, G.; Barad, Sanjay

doi:10.1155/2012/316761

Cited by 7 publications

(5 citation statements)

References 14 publications

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“…For this purpose, a set of non-dimensional design parameters has been introduced (see Table 1b), characterising the main aspects of the dynamic behaviour of a turbine blade. These parameters, in part selected from the literature [6,13,38] …”

Section: Rig Concept and Non-dimensional Parametersmentioning

confidence: 99%

“…In the simplified test rig the damper maximum acceleration is governed by the flexibility of the wire-pulley system. C) the displacement ratio [38], which is the ratio between the horizontal displacement of the platform and the horizontal displacement of the blade tip in the first flexural mode of the blade. Higher values cause more relative motion at the damper interface, leading to more energy dissipated.…”

Section: B)mentioning

confidence: 99%

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Modelling the nonlinear behaviour of an underplatform damper test rig for turbine applications

Pesaresi

Salles

Jones

et al. 2017

Mechanical Systems and Signal Processing

145

108

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Underplatform dampers (UPD) are commonly used in aircraft engines to mitigate the risk of high-cycle fatigue failure of turbine blades. The energy dissipated at the friction contact interface of the damper reduces the vibration amplitude significantly, and the couplings of the blades can also lead to significant shifts of the resonance frequencies of the bladed disk. The highly nonlinear behaviour of bladed disks constrained by UPDs requires an advanced modelling approach to ensure that the correct damper geometry is selected during the design of the turbine, and that no unexpected resonance frequencies and amplitudes will occur in operation. Approaches based on an explicit model of the damper in combination with multi-harmonic balance solvers have emerged as a promising way to predict the nonlinear behaviour of UPDs correctly, however rigorous experimental validations are required before approaches of this type can be used with confidence.In this study, a nonlinear analysis based on an updated explicit damper model having different levels of detail is performed, and the results are evaluated against a newly-developed UPD test rig. Detailed linear finite element models are used as input for the nonlinear analysis, allowing the inclusion of damper flexibility and inertia effects. The nonlinear friction interface between the blades and the damper is described with a dense grid of 3D friction contact elements which allow accurate capturing of the underlying nonlinear mechanism that drives the global nonlinear behaviour. The introduced explicit damper model showed a great dependence on the correct contact pressure distribution. The use of an accurate, measurement based, distribution, better matched the nonlinear dynamic behaviour of the test rig. Good agreement with the measured frequency response data could only be reached when the zero harmonic term (constant term) was included in the multi-harmonic expansion of the nonlinear problem, highlighting its importance when the contact interface experiences large normal load variation. The resulting numerical damper kinematics with strong translational and rotational motion, and the global blades frequency response were fully validated experimentally, showing the accuracy of the suggested high detailed explicit UPD modelling approach.

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Section: Rig Concept and Non-dimensional Parametersmentioning

confidence: 99%

Section: B)mentioning

confidence: 99%

Modelling the nonlinear behaviour of an underplatform damper test rig for turbine applications

Pesaresi

Salles

Jones

et al. 2017

Mechanical Systems and Signal Processing

145

108

View full text Add to dashboard Cite

show abstract

“…This suggests that the excitation frequency could well vary beyond the modelled cruise natural frequency range of mode 5, and approach the mode 6 natural frequency of 30472 Hz, as determined in the two-dimensional model. Therefore, resonance vibrations of blades can be expected even under normal turbine operating conditions, which is often addressed using appropriate dampers (Giridhar et al, 2012;Gastaldi et al, 2018). Furthermore, resonance vibrations of turbine blades in particular, and vibration characteristics of critical components in general, have proven to be a good overall metric for assessing the health of components (Hou et al, 2002;Al-Bedoor et al, 2006;Farrar et al, 2021).…”

Section: Potential For Monitoring Tbc and Blade Damage Using Resonance Vibration Measurementsmentioning

confidence: 99%

Assessment of Substrate and TBC Damage Effects on Resonance Frequencies for Blade Health Monitoring

Dyke

Nganbe

2022

International Journal of Manufacturing, Materials, and Mechanical Engineering

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The reliability of critical aircraft components continues to shift towards onboard monitoring to optimize maintenance scheduling, economy efficiency and safety. Therefore, the present study investigates changes in dynamic behavior of turbine blades for the detection of defects, with focus on substrate cracks and TBC spallation as they relate to vibration modes 1 to 6. Two‐dimensional and three-dimensional finite element simulation is used. The results indicate that TBC spallation reduces natural frequencies due to the ensuing hot spot and overall increase in temperature, leading to drops in blade stiffness and strength. Cracks cause even larger frequency shifts due to local plastic deformation at the crack that changes the energy dissipation behavior. Mode 1 vibration shows the largest shifts in natural frequencies that best correlate to the size of defects and their position. As such, it may be most appropriate for the early assessment of the severity and location of defects.

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“…For this purpose a set of nondimensional design parameters (Table 1) characterising the main aspects of the dynamic behaviour of a turbine blade has been introduced. These parameters, in part selected from the literature [10,14,22] and in part newly defined, are:…”

Section: Upd Rig Developmentmentioning

confidence: 99%

“…C) The displacement ratio [22] is the ratio between the horizontal displacement of the platform and the horizontal displacement of the blade tip in the first flexural mode of the blade. Higher values cause more relative motion at the damper interface leading to more energy dissipated.…”

Section: F)mentioning

confidence: 99%

Numerical and Experimental Investigation of an Underplatform Damper Test Rig

Pesaresi

Salles

Elliott

et al. 2016

AMM

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During operation mechanical structures can experience large vibration amplitudes. One of the challenges encountered in gas-turbine blade design is avoiding high-cycle fatigue failure usually caused by large resonance stresses driven by aeroelastic excitation. A common approach to control the amplitude levels relies on increasing friction damping by incorporating underplatform dampers (UPD). An accurate prediction of the dynamics of a blade-damper system is quite challenging, due to the highly nonlinear nature of the friction interfaces and detailed validation is required to ensure that a good modelling approach is selected. To support the validation process, a newly developed experimental damper rig will be presented, based on a set of newly introduced non-dimensional parameters that ensure a similar dynamic behaviour of the test rig to a real turbine blade-damper system. An ini- tial experimental investigation highlighted the sensitivity of the measured response with regards to settling and running in of the damper, and further measurements identified a strong dependence of the nonlinear behaviour to localised damper motion. Numerical simulations of the damper rig with a simple macroslip damper model were performed during the preliminary design, and a comparison to the measured data highlighted the ability of the basic implicit model to capture the resonance frequencies of the system accuratelyю

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Gas Turbine Blade Damper Optimization Methodology

Cited by 7 publications

References 14 publications

Modelling the nonlinear behaviour of an underplatform damper test rig for turbine applications

Modelling the nonlinear behaviour of an underplatform damper test rig for turbine applications

Assessment of Substrate and TBC Damage Effects on Resonance Frequencies for Blade Health Monitoring

Numerical and Experimental Investigation of an Underplatform Damper Test Rig

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