Theoretical and numerical analysis of theinteraction between dynamics and

chemistry in reactive flows

Federico Bianco

bianco@dalembert.upmc.fr

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

Thank you for your kind attention!

Federico Bianco

bianco@dalembert.upmc.fr