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Research Papers: Gas Turbines: Structures and Dynamics

On the Effect of Transient In-Plane Dynamics of the Compression Ring Upon Its Tribological Performance

[+] Author and Article Information
C. Baker, R. Rahmani, H. Rahnejat

Wolfson School of Mechanical &
Manufacturing Engineering,
Loughborough University,
Loughborough LE11 3TU, UK

S. Theodossiades

Wolfson School of Mechanical &
Manufacturing Engineering,
Loughborough University,
Loughborough LE11 3TU, UK
e-mail: s.theodossiades@lboro.ac.uk

B. Fitzsimons

Aston Martin Lagonda,
Gaydon,
Warwickshire CV35 ODB, UK

1Corresponding author.

Contributed by the Structures and Dynamics Committee of ASME for publication in the JOURNAL OF ENGINEERING FOR GAS TURBINES AND POWER. Manuscript received June 20, 2014; final manuscript received July 4, 2014; published online October 14, 2014. Editor: David Wisler.

J. Eng. Gas Turbines Power 137(3), 032512 (Oct 14, 2014) (11 pages) Paper No: GTP-14-1296; doi: 10.1115/1.4028496 History: Received June 20, 2014; Revised July 04, 2014

Energy losses in an internal combustion engine are either thermal or parasitic. The latter are the mechanical inefficiencies, chiefly as the result of generated friction. Nearly half of these losses are attributed to the piston–cylinder system. During idle and at low engine speeds, friction is the major contributor to the overall engine losses. In particular, the rather small top compression ring accounts for a disproportionate share. Therefore, detailed understanding of compression ring tribology/dynamics (referred to as tribodynamics) is essential. Moreover, the ring’s primary sealing function may be breached by its elastodynamic behavior. The reported analyses in literature do not account for the transient nature of ring elastodynamics, as an essential feature of ring–bore tribology. The transient in-plane dynamics of incomplete rings are introduced in the analysis and verified using a finite element analysis (FEA) model, in order to address this shortcoming. The methodology is then coupled with the tribological analysis of the top compression ring. Comparison is made with experimental measurements which show the validity of the proposed method. The radial in-plane elastodynamic response of the ring improves the accuracy of the frictional power loss calculations.

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References

Figures

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Fig. 1

Comparison between new and worn ring profiles

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Fig. 2

Pressure variation in the combustion chamber for different engine speeds

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Fig. 3

Free-body diagram of the in-plane forces acting upon the piston ring within its groove

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Fig. 4

(a) Degrees of freedom when discussing the in-plane dynamics [30] and (b) forces and moments acting upon a ring segment [9]

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Fig. 5

Algorithm of the coupling between the tribology and dynamics methodologies

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Fig. 6

Minimum film thickness comparison of rigid and elastic ring analysis for lubricant temperature 40 °C

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Fig. 7

Frictional power loss comparison of rigid and elastic ring analysis for lubricant temperature 40 °C

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Fig. 8

Lubricant mass flow rate comparison of rigid and elastic ring analysis at ring’s middle cross section for lubricant temperature 40 °C

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Fig. 9

Circumferential and axial profiles of the lubricant pressure and film shape at TDC ((a) and (b)) and 90 deg past TDC ((c) and (d))

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Fig. 10

Engine speed effect on minimum film thickness predictions for rigid and elastic ring analysis (lubricant temperature 40 °C)

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Fig. 11

Effect of engine speed on frictional power loss predictions for rigid and elastic ring analysis (lubricant temperature 40 °C)

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Fig. 12

Effect of engine speed on lubricant flow rate predictions for rigid and elastic ring analysis (lubricant temperature 40 °C)

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Fig. 13

Effect of temperature on the minimum film thickness (elastic ring analysis)

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Fig. 14

Effect of temperature on friction power loss (elastic ring analysis)

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Fig. 15

Effect of temperature on lubricant mass flow rate (elastic ring analysis)

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Fig. 16

Total cyclic energy consumed for rigid and elastic rings

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Fig. 17

Experimental data in comparison with the presented methodology (2000 rpm)

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Fig. 18

Experimental data in comparison with the presented methodology (2400 rpm)

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