This document summarizes a study investigating the damping potential of a strip damper on a turbine blade. A finite element model was created to model the strip damper with both free-free and constrained boundary conditions. The model found that a thin strip damper provided significant damping, and was more effective at lower nodal diameters where blade-disk motion is strongly coupled. The results require experimental verification.

1. INVESTIGATION OF DAMPING POTENTIAL OF
STRIP DAMPER ON A REAL TURBINE BLADE
Mohammad Afzal Ines Lopez Arteaga
mafzal@kth.se inesla@kth.se
KTH Royal Institute of Technology KTH Royal Institute of Technology
Leif Kari Vsevolod Kharyton
leifkari@kth.se vsevolod.kharyton@siemens.com
KTH Royal Institute of Technology Siemens Industrial Turbomachinary AB
GT2016-57230

2. Strip damper
2
Strip damper
§ Used to prevent the cooling air leakage
§ Provides a significant amount of friction damping.
(Vibration measurement at Siemens Industrial Turbomachinary AB
Finspang Sweden)

3. Literature review
3
§ Explicit finite element models of friction dampers in forced response analysis of
bladed disks – Petrov 2008
§ A lot of studies on UPDs are available. Where UPDs are often modelled as rigid
body.
§ Few studies have considered UPD as elastic body. (Cigeroglu-2008, Zucca-2012)
§ Few studies are done for ring dampers with elastic formulation. (D.Laxalde-2010)

4. How to model it?
4
Constrained boundary
§ A finite element model is required
§ Not connected to the blade platform
§ Free-Free or constrained boundary condition on
the strip?
§ Strip motion is constrained by the blade platform
Free-Free

5. Effect of boundary condition
5

6. Modelling and solution method
6
§ Tuned bladed disk with cyclic boundary condition
Cyclic
symmetry
n = temporal harmonic
m = spatial harmonic
= Number of sectors

7. Modelling and solution method
7
Ø Applying MHBM and receptance based approach
Ø Modal reduction method to compute the FRF
A high-accuracy model reduction for analysis of nonlinear
vibrations in structures with contact interfaces – Petrov 2011
Computed once at preselected frequency
Few dynamic modes are required

8. Modelling and solution method
8
§ 3D friction contact model in AFT frame work
§ Analytical Jacobian
+ Jacobian

9. CTA Blade-146 sectors
9
Low pressure turbine (CTA)

10. CTA Blade-146 sectors
10
1. EO3 and MF2
2. EO6 and MF4

11. Amplitude at the response node
11

12. Amplitude at the response node
12

13. Amplitude on the strip damper
13

14. Force balance on the strip
14

15. Example-effect of strip thickness
15

16. Example-effect of engine
excitation amplitude
16

17. Example-effect of strip damper
on different nodal diameters
17

18. Conclusions
18
§ The strip damper with different boundary conditions (free-free and elastic) is
investigated for different thicknesses.
§ A marginal effect of the boundary condition is observed on the nonlinear forced
response curve.
§ A significant amount of damping in the system can be achieved with a very thin
strip (H3 and mass = 2g)
§ The strip damper is more efficient for low nodal diameters, where blade-disk
motion is strongly coupled.
§ The obtained results require experimental verification.

19. Acknowledgement
19

20. 20