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Research Papers: Gas Turbines: Oil and Gas Applications

Influence of Blade Deterioration on Compressor and Turbine Performance

[+] Author and Article Information
M. Morini, M. Pinelli, P. R. Spina, M. Venturini

Engineering Department in Ferrara (ENDIF), University of Ferrara, Via Saragat, 1, 44100 Ferrara, Italy

J. Eng. Gas Turbines Power 132(3), 032401 (Nov 24, 2009) (11 pages) doi:10.1115/1.4000248 History: Received July 04, 2008; Revised July 10, 2008; Published November 24, 2009; Online November 24, 2009

Gas turbine operating state determination consists of the assessment of the modification due to deterioration and fault of performance and geometric data characterizing machine components. One of the main effects of deterioration and fault is the modification of compressor and turbine performance maps. Since detailed information about actual modification of component maps is usually unavailable, many authors simulate the effects of deterioration and fault by a simple scaling of the map itself. In this paper, stage-by-stage models of the compressor and the turbine are used in order to assess the actual modification of compressor and turbine performance maps due to blade deterioration. The compressor is modeled by using generalized performance curves of each stage matched by means of a stage-stacking procedure. Each turbine stage is instead modeled as two nozzles, a fixed one (stator) and a moving one (rotor). The results obtained by simulating some of the most common causes of blade deterioration (i.e., compressor fouling, compressor mechanical damage, turbine fouling, and turbine erosion), occurring in one or more stages simultaneously, are reported in this paper. Moreover, compressor and turbine maps obtained through the stage-by-stage procedure are compared with the ones obtained by means of map scaling. The results show that the values of the scaling factors depend on the corrected rotational speed and on the load. However, since the variation in the scaling factors in the operating region close to the design corrected rotational speed is small, the use of the scaling factor as health indices can be considered acceptable for gas turbine health state determination at full load. Moreover, also the use of scaled maps in order to represent compressor and turbine behavior in deteriorated conditions close to the design corrected rotational speed can be considered acceptable.

Copyright © 2010 by American Society of Mechanical Engineers
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Figures

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Figure 1

Compressor efficiency and pressure ratio versus corrected mass flow: (—) new and clean condition; (---) 5% reduction in the scaling factors for efficiency and 10% for corrected mass flow

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Figure 2

Effect of fouling on the first compressor stage (ΔA∗=−10% and Δη∗=−5%)

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Figure 3

Effect of gradual fouling on all the stages

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Figure 4

Effect of fouling on the whole compressor (ΔA∗=−10% and Δη∗=−5%)

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Figure 5

Effect of fouling (ΔA∗/Δη∗=2) on the nondimensional corrected mass flow in the choked region for the reference corrected rotational speed (ν∗=1.0)

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Figure 6

Effect of mechanical damage on the first compressor stage (Δη∗=−5%)

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Figure 7

Effect of fouling on turbine first stator (ΔA∗=−6% and ΔY∗=+3%)

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Figure 8

Effect of gradual fouling on the whole turbine

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Figure 9

Effect of fouling on the whole turbine (ΔA∗=−6% and ΔY∗=+3%)

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Figure 10

Effect of erosion on turbine first stator (ΔA∗=+6%)

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Figure 11

Effect of erosion on the whole turbine (ΔA∗=+6%)

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Figure 12

Effect of turbine first stator fouling and erosion on turbine nondimensional corrected mass flow in the choked region (ν∗=1.0)

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Figure 13

(a) Compressor pressure ratio curve scaling, (b) compressor efficiency curve scaling (β∗−η∗ coordinates), and (c) compressor efficiency curve scaling (η∗−μ∗ coordinates)

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Figure 14

Error on mass flow rate for scaling and translation for fouling (ΔA∗=−10% and Δη∗=−5%) occurring in the compressor first stage

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Figure 15

Error on efficiency for scaling and translation for fouling (ΔA∗=−10% and Δη∗=−5%) occurring in the compressor first stage

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Figure 16

Error on mass flow rate for scaling and translation for fouling (ΔA∗=−6% and ΔY∗=+3%) in the first turbine stator

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Figure 17

Error on efficiency for scaling and translation for fouling (ΔA∗=−6% and ΔY∗=+3%) in the first turbine stator

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Figure 18

Generalized stage characteristics ψp∗=ψp∗(ϕ∗,SF)(13) and experimental data (34)

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Figure 19

Generalized stage efficiency curve

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Figure 20

Nozzle thermodynamic transformation

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Figure 21

Example of stator and rotor matching

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