Simulation of soot emission

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Simulation is illustrated on the example:
Calculation of smoke emission during the operation of an automobile diesel engine KamAZ 7405 at the speed performance.

The calculation of emission of smoke is made in view of influence of burning process of the sprayed fuel. It is accepted that soot particles will be formed mainly by two ways:
- As a result of chain destructive transformation of molecules of fuel diffusing from the surface of drops to the front of a flame;
- Owing to high-temperature thermal polymerization and dehydrogenization of a vapour-liquid core of evaporating drops.
Parallel to this is the process of combustion of particles of soot and reduction of their volumetric concentration owing to expansion.

The results of calculation of rate of soot particles formation and combustion

Regime of full load: rpm=2200, BMEP=9.5 bar

dSmoke/dt is rate of soot particles formation and burning off;
dx/dt is heat release rate.

At the end of combustion the obtained concentration of soot is translated into the parameters of Hartridge, Bosch scale and also into the factor of absolute light absorption.

Comparison between  calculated soot emission level (Hartridge) and measured one.

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The  speed performance is submitted by three regimes. The experimental data are obtained by joint-stock company "KamAZ".

Visualization of mixture formation and combustion.

Regime of complete capacity:
rpm=2200,
BMEP=9.5 bar

 

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