Post Injection Process in Port Injection Systems

1
Post Injection Process in Port Injection Systems

• P M V Subbarao
• Professor
• Mechanical Engineering Department

Occurrence of an unwanted Process along with
Vaporization.
2
Fuel Droplet Dynamics Prediction of Arrival
3
Flow Simulation
Compute the air velocity distribution. Use this
data and distance between the injection nozzle
and intake valve, the timing at which the fuel
spray reaches the intake valve or manifold valve
or any other surface before entering the
cylinder is to be predicted.
4
Prediction of Droplet Paths

• After the spray break up there is a drag force
  exerted on the droplets from the surrounding
  gases.
• This drag tends to decrease the relative
  velocity between the drop and the gas flow.
• From the Newton's Second Law, the equation is

Where dsmd is the droplet diameter, ug and usmd
are the velocities of the gas flow and the liquid
fuel droplet, respectively. And the drag
coefficient CD is given as
5
Spray Length in quiescent Gas Medium
6
Droplet Impingement Process
7
Variation of Volume Fluxes
8
Deposited Film Mass Fraction
9
Complex Multi-Physics leading to Random Results
10
YAMAHA MOTOR TECHNICAL REVIEW

• Shoichi Kato, Takanori Hayashida, Minoru Iida

AFR 14.5, Coolant Temp. 80?
MEP 380 kPa,
11
Analysis Of Mixture And Wall Film Behavior
The injection system configuration, injection
timing and coolant temperature exert an influence
on combustion stability and duration.
Change of injection affects mixture formation in
the intake port, wall film location and amount,
size and amount of droplets, and finally mixture
distribution in the combustion chamber.
12
Proposal - 1
13
Proposal - 2
14
Proposal - 3
15
Proposal - 4
16
The System Reliability
17
(No Transcript)
18
Simplified Engineering fuel Evaporation model

• In a simplified engineering model a
  representative diameter for the entire group is
  defined to compute evaporation rate.
• Equivalent diameter of same number of uniformly
  sized droplets having same total surface area.

19
Details of Heat and Mass Transfer across Droplet
20
Droplet evaporation

• The droplet evaporation rate is given by

where d is the droplet diameter, DAB the gas
diffusivity, Sh the non-dimensional Sherwood
number, and Bm the mass transfer number. The
mass transfer number BM is equal to
21
Port Fuel Injection System Locations of Film
Resevoirs
22
Partial-heating of the Intake Port
23
Surface temperature of the Port under different
heating powers.
24
Effect of PH on In-cylinder HC Concentration
25
Increment of in-cylinder HC concentration