New sequential combustion technologies for heavy …...CAPS Combus+on and Acous+cs for Power Systems Lab. Sequential combustors in modern gas turbines Nicolas Noiray 07/09/17 2 Ansaldo

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CAPSCombus+onandAcous+csforPowerSystemsLab.

Conference on Combustion in Switzerland 07.09.2017 – ETH Zurich Nicolas Noiray, Oliver Schulz CAPS Lab – D-MAVT – ETH

07/09/17 Nicolas Noiray 1

New sequential combustion technologies for heavy-duty gas turbines

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Sequential combustors in modern gas turbines


Ansaldo (formerly Alstom)

Sequential Combustion in H-Class gas turbines. More than 700 MW in combined cycle with approx. 62% plant efficiency

Increased operational flexibility Increased fuel flexibility

Lower emissions Higher CC efficiency

General Electrics

Adapted from US20100170216 A1 See also ASME paper GT2017-63998

See ASME paper GT2017-64790

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Associated scientific challenges Technological characteristics §  Increased complexity of the combustors architecture and

of the operating concept §  Auto-ignition plays a key role §  1st and 2nd stage flames influence each others Corresponding scientific needs §  Adequate combustion models for accurate simulations §  Validation from experimental data §  Deep understanding of ignition, anchoring, blow-off

physics §  Modeling and control of combustor dynamics


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Related research at CAPS


Experiments:

Generic sequential burner

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Experiments:

1st stage 2nd stage

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Compressible Reactive Large Eddy Simulations with autoignition chemistry

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CAPSCombus+onandAcous+csforPowerSystemsLab.07/09/17 Nicolas Noiray 7

Are these really autoignition fronts? Paper submitted to C&F:

Combustion regimes in sequential combustors: autoignition and flame

propagation at elevated temperature and pressure.

O. Schulz, N. Noiray

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Different types of 1D flames Autoignition front

Very lean condition: most reactive mixture fraction (shortest

autoignition delay)

Hot reactants propagating flame at stoichiometric

condition

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From flame propagation to autoignition: residence time

Conclusions from idealized 1D perfectly premixed situations can be very informative for the practical configurations (3D partially premixed and turbulent)

Critical paramters: •  Mixture fraction, •  Inlet velocity, •  Mixture residence time

upfront of the flame

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Sequential Combustor Configuration

Operating pressure 1 and 10 bar Inlet temperature 1350 and 1450 K

4

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Numercial Methods

•  LES with AVBP

•  12 millions mesh cells

•  Dynamic Thickened Flame (DTF) model

•  Analytically Reduced Chemistry

(ARC) scheme

•  Wall heat loss

(Gicquel et al. Comptes Rendus – Mec., 2011)

(Colin et al. Phys. Fluids, 2000)

5

(Schulz et al. Proc. Combust. Inst. 2016) (Jaravel et al. Proc. Combust. Inst. 2016) (Pepiot and Pitsch Combust. Flame, 2008)

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Autoignition versus propagation at 10 Bar

10 Bar “hot” inlet à Autoignition dominates

10 Bar “cold” inlet à Propagation dominates

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Ignition of sequential combustor

Conditions •  Operating pressure 10bar •  Simulated time 43ms •  1st stage power 300kW •  2nd stage power 300kW •  2nd stage global phi 0.76 •  2nd stage inlet T 1350K

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Ignition of sequential combustor

Conditions •  Operating pressure 1bar •  Simulated time 90ms •  1st stage power 30kW •  2nd stage power 30kW •  2nd stage global phi 0.76 •  2nd stage inlet T 1450K

Autoignition driven transient evolving to propagating flame

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Flame stabilisation mechanism of a reactive jet in crossflow Paper submitted to C&F:

Large eddy simulation of a reactive jet in hot vitiated crossflow: flame stabilisation

mechanism. O. Schulz, E. Piccoli, A. Felden,

G. Staffelbach, N. Noiray

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Premixed jet flame behavior in a hot vitiated crossflow of lean combustion products Wagner, Renfro, Cetegen, Combustion and Flame 176 (2017),

Conclusions/Outlook -  Windward flame anchoring closer to the

crossflow suggests that auto-ignition was most likely the dominant mechanism

-  Further characterization of out-of- plane

motion may be necessary to interpret principal strain rate behavior along the windward flame edge.

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Detailed experimental data available

PIV

PLIF

Velocity magnitude Vorticity

LIF CH2O LIF OH Heat release location deduced

from LIF

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3-d large eddy simulation

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Comparison with experiments

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Comparison with experiments

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Instantaneous snapshot from LES

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Windward flame stabilisation due to autoignition 1. Autoignition at most reactive

mixture fraction Z_mr

2. Heat transfer to higher Z

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3-D flame dynamics

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3-d flame vortex interaction

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Nonlinear response of auto-ignition flames to entropy waves

Combustion & Flame paper under revision: O. Schulz, N. Noiray

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The sound of flames


Gas turbine combustors

Boilers, Industrial furnaces

Power generation

Liquid Rocket Propellant

Solid Rocket Propellant

Aerospace

Afterburners

Aeronautics

Aero-engine combustors

Resonant feedback loop

Chamber acoustics

Reactive flow dynamics

p′u′

Q̇′

Pulsations-induced damages

Frequency

Time

Dynamic pressure

Frequency

Time

Structural vibrations

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Flame Response to Temperature Fluctuations

1350 K 1450 K

Gain 1.7 Gain 3.4

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Flame Response to Temperature Fluctuations

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Decrease of inlet temperature

1450 K

1350 K

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0-D Autoignition Delays (CANTERA)

1450 K

1350 K

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Non-linear flame response to T fluctuations

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§  Significant progress over the last years in terms of simulations and modeling capabilities

§  Research effort to be pursued in topics like

§  Auto-ignition in turbulent environment at relevant conditions, §  Analytically Reduced Chemistry, §  Combustion modelling for partially premixed flames, §  Combustor dynamics associated with entropy waves §  Passive and active control of combustor dynamics

§  Strong need for experimental data to develop and validate these combustion models


Conclusions and Outlook

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Acknowledgement

Documents

New sequential combustion technologies for heavy …...CAPS Combus+on and Acous+cs for Power Systems Lab. Sequential combustors in modern gas turbines Nicolas Noiray 07/09/17 2 Ansaldo