theoretical and numerical analysis of the interaction between ......theoretical and numerical...
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Theoretical and numerical analysis of theinteraction between dynamics and
chemistry in reactive flows
Federico Bianco
PhD Candidate:
Federico BiancoSupervisors:● Angelo Vulpiani● Sergio Chibbaro● Thomas Gomez
Reactive flows
Combustion
Plankton bloom
Stirred reactors
Theoretical and numerical analysis
of theinteraction between
dynamics and chemistry in reactive
flows
Need of reduced combustion models
Studies in this field which seek analytical conclusions use heuristic reasoning or simplified models...
Advection-Reaction-Diffusion (ARD) models:
Premixed combustion; Binary mixture; Passive advection;
density of themixture ;Y mass fractionof burnt gasses ;ui velocity of themixture ;D diffusioncoefficient of burnt gasses ; characteristic time of reaction ;RY suitable reactionmodel ;
Passive incompressible advection
The constant density model is one of the most used PDE combustion models...
… for the study of reaction enhancing due to the presence of advection
Without advection: (*) admits flat propagation front with laminar burning velocity of the order and thickness of the order
(*)
v 0~D /0~D
With advection: v fv0
Passive compressible advection
Shear flow Cellular flow
2D steady state advective fields:
Autocatalitic reaction
AB2A Y A∈[0,1] RY A=2
0
Y A 1−Y A
Instantaneous snapshot of the frontShear: Pe=100, Da=10
ε=0
ε=0.5
ε=0.5
ε=0.5
λ=0.2
λ=1
λ=2
ε=0
ε=0.5λ=π/20
ε=0.5λ=π/4
ε=0.5λ=π
Cellular: Pe=1000, Da=10
While crossing high density zones the front appears visibly stretched...
....nevertheless
Shear flow Cellular flow
The differences in terms of mean asymptotic front speed are almost negligible.
Micro-Combustors:
Experiments conducted by Maruta et al. show that instabilities in micro-combustors may be triggered by varying inflow conditions.
Oshibe et al. Combustion and Flame 157 (2010) 1572–1580Maruta et al. Proceedings of the Combustion Institute 30 (2005) 2429–2436
Flame images taken by a CH-filtered digital still camera
Experimental results:
Oshibe et al. Combustion and Flame 157 (2010) 1572–1580Maruta et al. Proceedings of the Combustion Institute 30 (2005) 2429–2436
Two ARD equation model:Constant density, passive advection, one-step reaction