An Experimental Investigation of the Dynamics of a Blade With Two Under-Platform Dampers

Botto, Daniele; Gastadi, Chiara; Gola, Muzio; Umer, Muhammad

doi:10.1115/1.4037865

Cited by 35 publications

(14 citation statements)

References 27 publications

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“…In the past ten years, the AERMEC lab at the Polytechnic of Turin has devoted time and effort in the direct experimental investigation of friction parameters on different type of friction contacts [28][29][30][31][32][33][34]. By using this experience on different test rigs, the design of a new test rig tailored on strip dampers is here proposed.…”

Section: Introductionmentioning

confidence: 99%

Modeling and Testing Friction Flexible Dampers: Challenges and Peculiarities

2018

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This paper deals with the dynamic of blades with strip dampers. The purpose is 1) to present the results of the dynamic numerical calculation, 2) to demonstrate the need for the experimental data on the blade-strip contact to be used as input to the calculation, 3) to propose a new test rig design to obtain them and 4) to test the key components of the new test rig. The forced responses of two blades coupled by a strip damper are calculated at different excitation and centrifugal force values. The dependence of the numerical results on the contact parameter values is confirmed in this significant reference case. The design of a new test rig is then proposed: both the blade frequency response function and the contact hysteresis cycles at the blade-strip contact are measured. It is shown how contact parameters can then be derived from experimental data. The main novelty of the test rig here proposed is the strip loading system, which simulates the uniform pressure distribution provided by the centrifugal force in real operating conditions. This loading system is non-contact and uses compressed air. Classical loading systems which see dead weights directly connected to the strip are assessed and their expected inadequacy is confirmed. The compressed air system is tested by measuring the pressure produced between strip and blades: pressure is uniform across the contact patch, constant in time and its mean value corresponds to realistic pressure values actually experienced by strip dampers during service.

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Section: Introductionmentioning

confidence: 99%

Modeling and Testing Friction Flexible Dampers: Challenges and Peculiarities

2018

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“…A dedicated experimental campaign, similar to the one performed for rigid dampers [42] is underway. Still gaining a full awareness of the influence each parameter has on the numerical prediction is a necessary step in the creation of a meaningful experimental campaign.…”

Section: Contact Model: Influence Of Contact Parametersmentioning

confidence: 99%

Forced Response Prediction of Turbine Blades with Flexible Dampers: The Impact of Engineering Modelling Choices

2017

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This paper focuses on flexible friction dampers (or "strips") mounted on the underside of adjacent turbine blade platforms for sealing and damping purposes. A key parameter to ensure a robust and trustworthy design is the correct prediction of the maximum frequency shift induced by the strip damper coupling adjacent blades. While this topic has been extensively addressed on rigid friction dampers, both experimentally and numerically, no such investigation is available as far as flexible dampers are concerned. This paper builds on the authors' prior experience with rigid dampers to investigate the peculiarities and challenges of a robust dynamic model of blade-strips systems. The starting point is a numerical tool implementing state-of-the-art techniques for the efficient solution of the nonlinear equations, e.g., multi-harmonic balance method with coupled static solution and state-of-the-art contact elements. The full step-by-step modelling process is here retraced and upgraded to take into account the damper flexibility: for each step, key modelling choices (e.g., mesh size, master nodes selection, contact parameters) which may affect the predicted response are addressed. The outcome is a series of guidelines which will help the designer assign numerical predictions the proper level of trust and outline a much-needed experimental campaign.

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“…A ds is the reduction rate of y 1sm and A dt is the reduction rate of y 1tm . A dt and A ds are expressed in Equation (10).…”

Section: The Vibration Reduction Characteristics Of the Systemmentioning

confidence: 99%

“…He B and Ouyang H studied the forced vibration response of a turbine blade with a new kind of under-platform damper, in which the vertical motion of the damper leads to time-varying contact forces and can cause horizontal stick-slip motion [8]. For understanding the actual dynamics of the blade-damper interaction, a novel experimental test rig was developed to extensively investigate the damper's dynamic behavior [9,10]. Umer and Botto [11] explored the contact forces and relative displacement between the damper-blade contact interface with an experimental study for the first time.…”

Section: Introductionmentioning

confidence: 99%