Numerical and Experimental Damping Assessment of a Thin-Walled Friction Damper in the Rotating Set-Up With High Pressure Turbine Blades

2006 ◽  
Author(s):  
J. Szwedowicz ◽  
C. Gibert ◽  
T. P. Sommer ◽  
R. Kellerer
Keyword(s):  
High Pressure ◽  
Contact Stiffness ◽  
Turbine Blades ◽  
Mode Shapes ◽  
Friction Damper ◽  
High Pressure Turbine ◽  
Friction Forces ◽  
Normal Contact ◽  
Contact Behaviour ◽  
Thin Walled

Under-platform friction dampers are preferably solutions for minimizing vibrations of rotating turbine blades. Solid dampers, characterized by their compact dimensions, are frequently used in real applications and often appear in patents in different forms. A different type of the friction damper is a thin-walled structure, which has larger dimensions and smaller contact stresses on a wider contact area in relation to the solid damper. The damping performance of a thin-walled damper, mounted under the platforms of two rotating, freestanding high pressure turbine blades is investigated numerically and experimentally in this paper. The tangential and normal contact stiffness, that are crucial parameters in optimal design of each friction damper, are determined from three-dimensional finite element (FE) computations of the contact behaviour of the thin-walled damper on the platform including friction and centrifugal effects. The computed contact stiffness values are applied to non-linear dynamic simulations of the analysed blades with the friction damper of a specified mass. These numerical analyses are performed in the modal frequency domain with a code, which is based on the Harmonic Balance Method (HBM) for the complex linearisation of friction forces. The blade vibrations are characterised by a set of the lowest FE mode shapes of one freestanding blade without damper. The dynamic results of the calculated blades with the damper are in good agreement with the measured data of the real mistuned system. In the analysed excitation range, the numerical performance curve of the thin-walled damper is obtained within the scatter band of the experimental results. For the known friction coefficients and available FE and HBM tools, the described numerical process confirms its usability in the design of under-platform dampers.

scholarly journals Optimization of Friction Damper Weight, Simulation and Experiments

1997 ◽  
Author(s):  
Gabor Csaba ◽  
Magnus Andersson
Keyword(s):  
Experimental Data ◽  
High Pressure ◽  
Turbine Blades ◽  
Turbine Rotor ◽  
Friction Damper ◽  
High Pressure Turbine ◽  
Coupled Modes ◽  
Modes Of Vibration ◽  
Damper Design ◽  
The Right

A new friction damper has been designed by Volvo Aero Corporation. It is used in the high pressure turbine stage of a turbojet engine. The objective of this paper was to find the optimal weight of the new damper that minimizes the blade response amplitude for six and nine engine order excitation and to compare the new damper design with that currently used. Another objective was to compare how well simulation results agree with experimental results from spin pit tests. Simulations were made with a damper model that incorporates the possibility of both micro- and macro-slip in the blade-damper contact interface. Turbine blades were modeled using finite element beam elements. Experimental data were provided from spin pit tests with a completely bladed high pressure turbine rotor. Results show that the simulation model can be used to give qualitative results but has to be further developed to incorporate mistuning effects and coupled modes of vibration for the blade. The spin pit test shows that the new damper design is more efficient in reducing resonance stresses than the old design. It was not possible to see if simulations predict the right optimal damper weight by comparing with experimental data because the rotor could not be excited up to the design point.

Aerothermal Effect of Cavity Welding Beads on a Transonic Squealer Tip

2020 ◽  
Author(s):  
Joao Vieira ◽  
John Coull ◽  
Peter Ireland ◽  
Eduardo Romero
Keyword(s):  
High Pressure ◽  
Film Cooling ◽  
Turbine Blades ◽  
Reynolds Numbers ◽  
High Pressure Turbine ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Aerodynamic Loss ◽  
Blade Tip ◽  
Mass Flow Rates

Abstract High pressure turbine blade tips are critical for gas turbine performance and are sensitive to small geometric variations. For this reason, it is increasingly important for experiments and simulations to consider real geometry features. One commonly absent detail is the presence of welding beads on the cavity of the blade tip, which are an inherent by-product of the blade manufacturing process. This paper therefore investigates how such welds affect the Nusselt number, film cooling effectiveness and aerodynamic performance. Measurements are performed on a linear cascade of high pressure turbine blades at engine realistic Mach and Reynolds numbers. Two cooled blade tip geometries were tested: a baseline squealer geometry without welding beads, and a case with representative welding beads added to the tip cavity. Combinations of two tip gaps and several coolant mass flow rates were analysed. Pressure sensitive paint was used to measure the adiabatic film cooling effectiveness on the tip, which is supplemented by heat transfer coefficient measurements obtained via infrared thermography. Drawing from all of this data, it is shown that the weld beads have a generally detrimental impact on thermal performance, but with local variations. Aerodynamic loss measured downstream of the cascade is shown to be largely insensitive to the weld beads.

scholarly journals Evaluation of High Pressure Turbine Blade Coatings on an LM2500 Rainbow Rotor

1995 ◽  
Author(s):  
B. Nagaraj ◽  
G. Katz ◽  
A. F. Maricocchi ◽  
M. Rosenzweig
Keyword(s):  
High Pressure ◽  
Turbine Blades ◽  
Leading Edge ◽  
Service Evaluation ◽  
High Pressure Turbine ◽  
Barrier Coating ◽  
Marine Propulsion ◽  
Corrosion Resistant Coatings ◽  
Stage 1 ◽  
Plasma Sprayed

Two LM2500 rainbow rotors with repaired stage 1 and stage 2 high pressure turbine blades are being assembled for marine propulsion service evaluation by the US Navy. The blades have seen between 5,000 and 15,000 hours of service in the Navy’s Fleets. A number of corrosion resistant coatings including plasma sprayed CoCrAlHf (bill of material), composite plated CoCrAlHf, platinum aluminide, aluminum silicide, and physical vapor deposited yttria stabilized zirconia thermal barrier coating (PVD TBC) will be evaluated in the rainbow rotor. This paper will discuss the advantages and microstructures of the various coatings. Composite plated CoCrAlHf, and PVD TBCs were recently service evaluated in an industrial LM2500 rainbow rotor for 10,500 hours. Both these coatings performed well, although the PVD TBC had local spallation at the leading edge. This paper will review the details of performance of these two coatings in the industrial LM2500 application.

Using CFD to Reduce Resonant Stresses on a Single-Stage, High-Pressure Turbine Blade

2002 ◽  
Author(s):  
J. P. Clark ◽  
A. S. Aggarwala ◽  
M. A. Velonis ◽  
R. E. Gacek ◽  
S. S. Magge ◽  
...  
Keyword(s):  
High Pressure ◽  
Turbine Blade ◽  
Guide Vane ◽  
Turbine Blades ◽  
Suction Side ◽  
Lessons Learned ◽  
Single Stage ◽  
Navier Stokes ◽  
High Pressure Turbine ◽  
Time Resolved

The ability to predict levels of unsteady forcing on high-pressure turbine blades is critical to avoid high-cycle fatigue failures. In this study, 3D time-resolved computational fluid dynamics is used within the design cycle to predict accurately the levels of unsteady forcing on a single-stage high-pressure turbine blade. Further, nozzle-guide-vane geometry changes including asymmetric circumferential spacing and suction-side modification are considered and rigorously analyzed to reduce levels of unsteady blade forcing. The latter is ultimately implemented in a development engine, and it is shown successfully to reduce resonant stresses on the blade. This investigation builds upon data that was recently obtained in a full-scale, transonic turbine rig to validate a Reynolds-Averaged Navier-Stokes (RANS) flow solver for the prediction of both the magnitude and phase of unsteady forcing in a single-stage HPT and the lessons learned in that study.

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