1. Basics of Fuel Injection in Ports
P M V Subbarao
Professor
Mechanical Engineering Department
Understand and Control Fuel Evaporation & Film Formation….

2. Fluid Dynamics of Spray for Port Injection

3. Actuation of Electronic Fuel Injector
Force Function

4. Anatomy of Electronic Fuel Injector
Solenoid Magnet

5. Actuation of Solenoid
The coil is solely responsible for lifting the plunger to deliver fuel.
When the solenoid is powered up, it acts as an electromagnet and attracts the permanent magnet attached towards the top of the plunger.
Stoppers ensure a fixed value of maximum lift.
ECU supplies DC current at 6 – 12 Volts, to deliver the characteristics of the solenoid.

6. Force applied by the Solenoid on the Rod
Final Magnetic Energy of the field
Initial Magnetic Energy of the field
Change in energy

7. Design of Solenoid A solenoid has the following design variables:
Number of turns per meter
Current passing through solenoid
Resistance of solenoid wire

8. Electrical Input to Control Injector Operation
An injector is essentially a gate valve for fuel delivery.
Increasing fuel pressure can allow to cram more fuel into the intake port for a given injector pulse width.
Injection Pulse
Full Open Accelerator
Once in two Revolutions
Idling
Cold Starting

9. Injector characteristics analysis

10. Transient driving Pressure for Fuel Flow
The pressure gradient across the injector openings can be defined as a rectangular pulse train.
For our calculations, this pulse train in real time is mapped as a Fourier series with non-dimensional time and frequency as governing parameters.

11. New Chapter in Fluid Mechanics
Fully developed axisymmetric pulsating laminar pipe flow.
The Navier-Stokes equation for an axisymmetric flow can be written as:
The pressure gradient in the above equation can be written in the form of a Fourier transform as discussed above.
The equation when solved gives absolute flow velocity and mass flow rate mapped against time in a complex space:

12. Instantaneous Mass Flow Rate
The mass flow rate can then be solved for:
The non-dimensional frequency and time are given as below
R is the radius of the nozzle tip.

13. Transient Response of Injector

14. Flow Characteristics of Injector - 1

15. Throttle Body Injector
Flow Characteristics of Injector - 2
Throttle Body Injector
7.0 gms/s
Port Injector
3.5 gms/s

16. Instability of Fluid Ligament in Ambient Air

17. Gasoline Fuel Sprays in Port

18. Mean diameter distribution of droplets (micron) in 100 mm downstream and 300 Kpa, 25o C

19. Distribution of droplets velocity (m/s) in 100 mm downstream and 300 Kpa, 25o C