12/22/2009 1 Optimisation for Thermo-Fluids Engineering Dr. R.J.M. (Rob) Bastiaans Combustion Technology Mechanical Engineering 4M020 Design Tools 4M020 Design Tools; Optimisation in Thermo-Fluids Engineering Optimisation Eggert 2000: Engineering design Engineering design is the set of decision-making processes and activities used to determine the form of an object given the functions desired by the customer. During the parametric design phase we determine values for the controllable parameters, called design variables, identified as unknown during the configuration phase. CAE refers to computer software and hardware systems used in the analysis of engineering designs to validate functional performance. 4M020 Design Tools; Optimisation in Thermo-Fluids Engineering Thermo-Fluids Engineering What is Thermo-Fluids Engineering Covered by Energy Technology Process Technology Combustion Technology Common factor: Fluid flow Often multi-scale multi-physics problems Much research less optimal design Implication on how to use computer-capacity 4M020 Design Tools; Optimisation in Thermo-Fluids Engineering Fluid Flow Many problems in many areas Meteorology Astrophysics Biology Agriculture Process technology Common factor: Navier Stokes Equations 4M020 Design Tools; Optimisation in Thermo-Fluids Engineering Multi-Scale flows Examples Turbulence Atmospheric dispersion 4M020 Design Tools; Optimisation in Thermo-Fluids Engineering Multi-Physics Often flow is not the problem but interactions are Buoyancy induced flows Mixing of different fluids Dispersion of pollutants Flows with heat transfer Reactive flows; combustion Compressible flows Acoustics Shock waves MHD (Magneto Hydro-Dynamics) Flow structure interaction Combinations of the above
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12/22/2009
1
Optimisation for Thermo-Fluids
Engineering
Dr. R.J.M. (Rob) Bastiaans
Combustion Technology
Mechanical Engineering
4M020 Design Tools
4M020 Design Tools; Optimisation in Thermo-Fluids Engineering
Optimisation
Eggert 2000: Engineering design
� Engineering design is the set of decision-making
processes and activities used to determine the form of
an object given the functions desired by the customer.
� During the parametric design phase we determine values
for the controllable parameters, called design variables,
identified as unknown during the configuration phase.
� CAE refers to computer software and hardware systems
used in the analysis of engineering designs to validate
functional performance.
4M020 Design Tools; Optimisation in Thermo-Fluids Engineering
Thermo-Fluids Engineering
What is Thermo-Fluids Engineering
� Covered by
� Energy Technology
� Process Technology
� Combustion Technology
� Common factor: Fluid flow
� Often multi-scale multi-physics problems
� Much research less optimal design
� Implication on how to use computer-capacity
4M020 Design Tools; Optimisation in Thermo-Fluids Engineering
Fluid Flow
Many problems in many areas
� Meteorology
� Astrophysics
� Biology
� Agriculture
� Process technology
Common factor: Navier Stokes Equations
4M020 Design Tools; Optimisation in Thermo-Fluids Engineering
Multi-Scale flows
Examples
� Turbulence
� Atmospheric dispersion
4M020 Design Tools; Optimisation in Thermo-Fluids Engineering
Multi-Physics
Often flow is not the problem but interactions are
� Buoyancy induced flows
� Mixing of different fluids
� Dispersion of pollutants
� Flows with heat transfer
� Reactive flows; combustion
� Compressible flows
� Acoustics
� Shock waves
� MHD (Magneto Hydro-Dynamics)
� Flow structure interaction
� Combinations of the above
12/22/2009
2
4M020 Design Tools; Optimisation in Thermo-Fluids Engineering
Multi-Scale Multi-Physics flows research
Examples
� Turbulent combustion:
� Compressible flow
� Heat transfer
� Many chemical species and reactions
� Acoustics, stability
� Flame-thickness independent length scale
� Application: Gas-turbines for aeroplanes and el. power generation
� Very important for society: Emissions, Climate, Energy
� Optimisation??
4M020 Design Tools; Optimisation in Thermo-Fluids Engineering
Multi-Scale Multi-Physics flows research
Gas turbines:
4M020 Design Tools; Optimisation in Thermo-Fluids Engineering
Modelling of reactive flows
Turbulent combustion
� Not only interesting from an industrial point of
view, but also from an academic point of view
� Large range of time and length scales makes
numerical simulation of turbulent combustion
far from easy and very expensive
� Development of accurate and efficient models
for turbulent combustion is one of the most
challenging tasks facing the combustion
community today
DL
R, G
erm
an
y
4M020 Design Tools; Optimisation in Thermo-Fluids Engineering
Approach
From small to large scale, from fundamentals to application
� One-dimensional flame modelling with detailed description of
chemistry and transport
� Flamelet-based reduction (FGM) to simplify chemistry model
� Direct numerical simulation (DNS) of turbulent flame to unravel
chemistry-turbulence interaction
� Model for turbulence-chemistry interaction (e.g. a sub-grid scale
model for large-eddy simulations)
� Large-eddy simulation (LES) of lab-scale flames
� Reynolds-averaged Navier-Stokes (RANS) simulations of
industrial applications
4M020 Design Tools; Optimisation in Thermo-Fluids Engineering
DNS of turbulent flame kernels
DNS of spherically expanding premixed
turbulent flames
� Validation of FGM vs detailed chemistry
� Analyse turbulence/chemistry interaction
� Practical relevance is found in IC engines
Leeds, UK
4M020 Design Tools; Optimisation in Thermo-Fluids Engineering
Validation of FGM
Mass fraction of OH radical. FGM 100 times faster than detailed chemistry!
This enables paramteric studies.
12/22/2009
3
4M020 Design Tools; Optimisation in Thermo-Fluids Engineering
From DNS to LES of reactive flows
� Averaging DNS results enables a-priori testing of LES sub-grid scale
models.
� Application of LES-FGM in premixed turbulent Bunsen flame:
4M020 Design Tools; Optimisation in Thermo-Fluids Engineering
RANS of gas turbine combustor
NOx formation in gas turbine combustor
� Fired in lean premixed mode:
� Fired in diffusion mode (start-up): NOmax is ~100x larger
� Investigate the influence of hydrogen addition
4M020 Design Tools; Optimisation in Thermo-Fluids Engineering
Application to biomass conversion
� Application of fundamental knowledge of reactive flows to biomass
conversion
� Multi-scale, multi-physics approach:
� Small scale: single particle
kinetics, pyrolysis, heat/mass transfer
� Intermediate scale: fixed/fluidized bed
two-phase flow, heat/mass transfer
� Large scale: reactor, furnace
flow pattern, radiation, control
Info
rma
tion
4M020 Design Tools; Optimisation in Thermo-Fluids Engineering