Views
5 years ago

chapter 5 turbulent diffusion flames - FedOA

chapter 5 turbulent diffusion flames - FedOA

combustion systems:

combustion systems: laminar premixed flames, laminar and turbulent diffusion flames and practical systems like in engines. Furthermore, these efforts toward the understanding of the LII technique have been focused on the modeling and theoretically interpretation of the LII signal and on the improvement of the experimental procedures. On the basis of all the models, developed to describe the heating and cooling mechanisms important for LII detection of soot, there are same simplifications that can be so reassumed [54]: • As described above soot is mainly composed by spherical particles, called primary particles, with typical diameter in the range 10 – 30 nm, that agglomerate forming structure composed by a few up to thousands primary particles, Dobbins [28]. Normally, in the LII models these aggregates are idealized as composed by particles all of identical diameter, dp, touching at only one point. Therefore the soot volume fraction is simply given by the expression: fv = (π/6) N np dp 3 , where N is the number density of aggregates and np is the average number of primary particles per aggregate. • The second simplification assumes that the LII signal is based on the energy and mass balance between a single soot particle and its surrounding rather than the aggregate. • The third simplification requires that temperature gradients inside the particles can be neglected. Starting from the fundamental modelling work of Melton [53] the energy balance for a spherical particle of radius a can so write: 2 ( T − T )( π ) 38 2 4 4 4 dT ( 4πa ) εσ ( T − T ) − πa ρ c = 0 2 K a 0 4 a ΔH v dm 3 K abs ( a) π a q − + − SB 0 s s a( 1+ GK n ) M dt 3 dt

where the five terms represent in the order: the absorption rate of laser energy, the heat transfer by conduction, the vaporization energy of soot, the energy loss by blackbody radiation and the change in internal energy. However, for the correct interpretation of the incandescence signals, the different terms of the equation needs to carefully modeled. The absorption coefficient Kabs of soot strongly depends on: the absorption wavelength, λ, on the particle diameter, di, and on the complex index of refraction of soot, m = n+ik. In the Rayleigh regime (π di / λ

Fuel effects on diffusion flames at elevated pressures - Turbulence ...
Soot formation in laminar diffusion flames - ResearchGate
Radiation and soot formation in a turbulent diffusion flame - ICHMT
soot formation in laminar diffusion flames - Yale University
Calculating soot in a turbulent jet diffusion flame using the unsteady ...
DNS of Turbulent Nonpremixed Ethylene Flames
Numerical Simulation of Turbulent Premixed Flames with ...
Soot formation in high-pressure laminar methane diffusion flames
Joint PDF Closure of Turbulent Premixed Flames - Italian Section of ...
Forced Time-Varying Methane Diffusion Flame - Yale University
Numerical Prediction of Sooting Laminar Diffusion Flames Using ...
Heat release rate measurement in turbulent flames
Effects of heat release in laminar diffusion flames - Mechanical ...
Shapes of Buoyant and Nonbuoyant Laminar Jet Diffusion Flames
Flame holes and flame disks on the surface of a diffusion flame
Soot Formation in an Ethylene Diffusion Flame
A STATISTICAL THEORY ON THE TURBULENT DIFFUSION OF ...
Measurement of flame surface density for turbulent premixed flames ...
Measurement of turbulent transport in premixed turbulent flames by ...
Sensitivity calculations in PDF modelling of turbulent flames
Investigation of differential diffusion in turbulent jet ... - Yale University
large eddy simulation of turbulent premixed flames propagation in a ...
A numerical study of auto-ignition in turbulent lifted flames issuing ...
large eddy simulation of turbulent premixed flames propagation in a ...
1 Kilohertz PIV/PLMS of low-gravity turbulent flames in a drop tower
Turbulent combustion (Lecture 3) Non-premixed flames
Numerical Simulation of the Dynamics of Turbulent Swirling Flames
Identification of low-dimensional manifolds in turbulent flames
Lagrangian properties of diffusion in the theory of turbulent combustion