1. Post Injection Processes in Diesel Engines
P M V Subbarao
Professor
Mechanical Engineering Department
Special Behavioral Issues of Teen Combustion ….

2. Sizing of Nozzle Instantaneous Diesel Flow rate:
Mass of Diesel per cycle:

3. Fuel Exiting into High Pressure& Temperature Air Enviroment : An unexplored Fluid Mechanics

4. Boiling in Nozzle due Improper Fluid Mechanics????
Nurick’s Number, K
pv is the vapor pressure of the fuel.

5. Optimal Design of Nozzle Hole

6. Effect of Nozzle Surface Finish : Distribution of Droplets

7. Distribution of Droplets in A Spray

8. Strong Influence of In-Cylinder Conditions on SMD
where do is the discharge orifice diameter and
FN is the nozzle flow number defined by

9. Where
is the liquid surface tension,
L is the liquid viscosity,
A is the air density,
 L is the liquid density,
pL, is the injection pressure differential across the nozzle,
is the half spray angle and
t is the film thickness, given by

10. Thermo-Fluid Dynamics of Injection
The basic processes are as follows.
The fuel injected into a combustion chamber gets divided into many zones.
Events in each zone are:
droplet break-up,
evaporation,
air–fuel mixing,
ignition,
heat release,
heat transfer and
formation of exhaust emits.
Each zone obtains its own zonal temperature and compositions.
The mass, internal energy and mole quantity of NOx of each zone are different.
The final effect of combustion is cylinder-averaged temperature, air–fuel ratio and NOx concentration.

11. Simultaneous Occurrence of Multiple Process in CI Engines
Start of
injection
End of
injecction
-10

12. Ignition Delay The sum of times required for sub process.
The most widely reported correlation relating the ignition delay to the ambient gas condition is given by the relation
where τ is the ignition delay, pg and Tg are the ambient gas mean pressure and temperature before autoignition takes place,
A, B and n are experimental constants.

13. Arhenius-type equation for Ignition Delay
An Arhenius type equation for Ignition delay is:
p :Premixed air fuel ratio.

14. Symptoms to be Sensed to Predict Auto Ignition

15. Effect of Gas Temperature on Ignition Delay

16. Effect of Equivalence Ratio on Ignition Delay

17. The flammability limits versus the number of carbon atoms in alkanes

18. Simultaneous Occurrence of Multiple Process in CI Engines
Start of
injection
End of
injecction
-10