Combustor Technology Turbo Power programme conference, 9 April 2014 Bernhard Gustafsson GKN Aerospace Engine Systems, Aerothermodynamics Daniel Lörstad Siemens Industrial Turbomachinery, Combustion Group

Outline Turbo Power goals related to the COMB area Future combustor requirements Syngas Gas turbine competitiveness, R&D hot topics Overview of a Combustor Development Process GKN Combustion activities COMB past and present projects

Excerpts from Turbo Power goals Turbo Power requirements related to COMB: Improved tools and modelling capabilities Enable fuel flexibility Increase knowledge within renewable low-caloric value gases and liquid bio-fuels. Increase design space, design capability and flexibility. Produce generic knowledge that can be applied to product development and commercialisation.

Flexible combustors for sustainable energy production Future combustors must be able to handle fuels from different sources and with different properties and compositions. Fuel-flexible combustion (process-controlled combustion). Possibilities to use low-calorific fuels from biomass. Usually a CO – H2 mixture. Flexible operation. Combustors must be able to operate at varying loads. Waste gases, peak loads etc. Allow exhaust gas recirculation (EGR) to facilitate carbon capture and sequestration (CCS) processing. High CO2 levels. All this in a safe, clean and efficient manner.

Syngas Synthesis gas (syngas) consists of H2, CO and some CO2 and inert. Intermediate gas in producing synthetic natural gas Can be produced by gasification of biomass Combustion challenges with syngas are: Low heating value causes high mass flow through the combustor, and possibly flame extinction. High laminar flame speed of H2 can cause flash-back Higher temperature at stoichiometric combustion than NG produces more NOx. Rich or lean combustion is needed, but is more prone to instabilities.

Gas turbine competitiveness R&D hot topics Efficiency High turbine inlet temperature and effective cooling Knowledge of turbine inlet depends on combustor knowledge Reliability, availability and life Combustion instabilities may lead to fatigue failure Total life cycle cost Emission levels Low NOx requires limited flame zone temperature and well mixed air/fuel Reduced NOx often leads to instabilities & increased CO/UHC Ability of flexibility Gas/liquid fuel type and energy content strongly influences the combustion Load flexibility to back up renewables SGT-750 37 MW, 40% Launched nov 2010 Data Power Efficiency Shaft 37.1 MW 40.0% Electric 35.9 MW 38.7% Combi 47.7 MW 51.7% High availability High serviceability Environmentally friendly

Common questions in R&D projects SGT-800 Performance Life Heat load & temperature Turbine inlet distribution Availability & reliability Combustion dynamics Thermo acoustics Emissions: NOx, CO, UHC Alternative fuels Cost Answers obtained through experience, modeling, rig and engine tests There is a need of increased accuracy of predictions to optimize the design potential and reduce lead time and costs Combustor flow paths, flame position and recirculation zones

Overview of Combustor Development Process Aero-combustion analysis Testing Mechanical integrity and design Concept Concept analysis 0.1-1MSEK Basic CFD AC testing Basic Mechanical Design Generic development process 1-20MSEK Detailed analyses (Complex CFD/acoustics/ chemistry) Mechanical integrity (heat trans/stress/life) HP testing Detailed Available budget for analyses depends on risks of: Not reaching goals Delays & increased budget Additional test periods 1-100MSEK Engine testing Proto-type design Validation

GKN Combustion activities RM12 main combustion chamber and afterburner Space nozzle extensions Acoustic treatments in combustors and ducts

COMB past and present projects Analysis of thermo-acoustic properties of combustors including liner wall modeling (COMB24) G. Jourdain & L.-E. Eriksson. Chalmers (COMPLETED) CFD Modeling of Flexi-Fuel Gas Turbine Combustor (COMB25 ) A. Abou-Taouk & L.-E. Eriksson. Chalmers (ONGOING) Prediction of gas turbine combustor performance based on optimal reduced kinetics and dynamic mode decomposition (COMBxx) ?. ? , N. Andersson & L.-E. Eriksson. Chalmers (NEW) Experimental investigation of flexible combustion at atmospheric and elevated pressure. (COMB26) I. Sigfrid, R. Whiddon, A. Kundu, A. A. Subash, R. Collin, J. Klingmann & M. Aldén. Lund University of Tech. (ONGOING)

Combustion instabilities Fuel-Oxidator ratio Residence time Temperature Heat release that couple, and that is in phase with, acoustic or hydrodynamic modes casues instabilities to grow. Fatigue and (catastrophic) failure of the combustor Heat release Acoustic / Hydrodynamic eigenmode P V P T f Disturbance

COMB 24 / Validation Rig 1 (1990) Buzz Screech Premixed propane flame behind a triangular flameholder

Modelling techniques studied in COMB Dynamic Mode Decomposition Snap-shots of the flow field Extraction of dominant dynamic modes Extraction of eigenvalues => frequency and damping Optimal global reaction schemes Reduction of detailed reaction schemes for syngas and methane Few global reactions => suitable for unstready 3D CFD (LES) Multi-target optimised reaction schemes w.r.t. adiabatic flame temperature laminar flame speed Perfectly Stirred Reactor effluents Flame thickness and species distribution in the flame

COMB 24 Eigenmode analysis of Validation Rig 1 Arnoldi method Linear Euler Equations Linear Navier Stokes Equations Dynamic Mode Decomposition Unsteady RANS Development of porous wall model for acoustic damping Arnoldi, damped mode DMD, undamped (correct) Incl. porous wall, damped

COMB 25 Unsteady 3D CFD (Hybrid URANS/LES) Temperature Unsteady 3D CFD (Hybrid URANS/LES) Optimization of global reaction schemes 4 global reactions sensitized to local fuel-air ratio Flame position is maintained by swirl Methane-Air mixture f=0.55 Large Eddy Simulations of an industrial burner, SGT-100, fed with Methane-Air. (A. Abou-Taouk) Reaction rate

High pressure rig - DESS COMB 26 Atmospheric rig Atmospheric testing & High pressure testing (DESS): Siemens RPL pilot burner Siemens DLE burner Simulated low-heating value fuels by dilution of inert Advanced non-intrusive measurement techniques: Gas analysis - emissions Particle Image Velocimetry Laser induced fluorescence of OH and formaldehyde Chemiluminescence High pressure rig - DESS from R. Whiddon (2014)

COMB 26 from R. Whiddon (2014)

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