Basics of Fuel Injection in Ports P M V Subbarao Professor Mechanical Engineering Department Understand and Control Fuel Evaporation & Film Formation….
Fluid Dynamics of Spray for Port Injection
Actuation of Electronic Fuel Injector Force Function
Anatomy of Electronic Fuel Injector Solenoid Magnet
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.
Force applied by the Solenoid on the Rod Final Magnetic Energy of the field Initial Magnetic Energy of the field Change in energy
Design of Solenoid A solenoid has the following design variables: Number of turns per meter Current passing through solenoid Resistance of solenoid wire
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
Injector characteristics analysis
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.
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:
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.
Transient Response of Injector
Flow Characteristics of Injector - 1
Throttle Body Injector Flow Characteristics of Injector - 2 Throttle Body Injector 7.0 gms/s Port Injector 3.5 gms/s
Instability of Fluid Ligament in Ambient Air
Gasoline Fuel Sprays in Port
Mean diameter distribution of droplets (micron) in 100 mm downstream and 300 Kpa, 25o C
Distribution of droplets velocity (m/s) in 100 mm downstream and 300 Kpa, 25o C