ANALYSIS OF AIR-FUEL FLOW

IN GASOLINE DIRECT INJECTION ENGINE

PROJECT GUIDE - Dr. J G SURYAWANSHISTUDENTS - NIKHIL MOORJANI

SHREYAS SHARMAESHANA RANAWAKA

Aim of the Project

Study the Technology behind Gasoline Direct Injection engine

Comparison of GDI engine with Carburetor and Multipoint Injection engines

To develop CFD fluid flow model inside a GDI engine using Fluent and Gambit Software.

Project Planning

Studying the Concept of GDI from various research papers and other study materials with the help of our Project guide.

Learning the CFD flow analysis software (FLUENT) and Solid modeling Software (GAMBIT).

Creating the necessary model and meshing it accordingly.

Carrying out the calculations of the flow and generating the graphical images of the simulation.

Comparing the results we obtained with the data already available in research papers and other sources.

Progress of the Project till now.

Studying the Theory and concept behind GDI Engine

Why GDI engines over Carburetor and MPFI engines?

Carburetor is a chamber where petrol and air was mixed in a fixed ratio and then sent to cylinders to burn it to produce power.

MPFI emerged an Intelligent way to do what the Carburetor does. In MPFI system, each cylinder has one injector (which makes it multi-point). Each of these Injectors are controlled by one central car computer.

Gasoline Direct Injection Engine The fuel is injected under high pressure directly into the combustion

chamber, just before ignition by the spark plug, this allows the precise control of charge stratification vital to ignite ultra-lean air / fuel mixtures.

Unlike conventional engines, GDI uses upright straight intake port, accompany with a concave-section piston surface, swirl air flow will be generated during compression stroke.

Fuel Injection takes place in two stages. One during the Suction stroke and second one just before the ignition

MERITS AND DEMERITS OF GDI ENGINE

oHigh Volumetric efficiency

oLower fuel consumption

oMore power output (Higher compression ratio 12.5 : 1)

oLower octane requirement

oMore rapid starting

oReduced CO2 emissions

oLower Octane requirement

oMore precise air-fuel ratio control

oImproved transient response

oOne of the few drawbacks of GDI engine is the higher NOX pollutant level.

oAutomobiles which uses GDI engines already Hyundai (Gamma, Lambda, Theta i & ii engines) Renault IDE Mitsubishi (Montero engine) General Motors

oMax Power Out put 180hp at 6700rpm (GM 2.4L 4 cyl inline with 11.4:1 compression ratio) 255hp at 214 lb-ft of torque (Chevrolet 3L V6 ) 200hp 2L VW

oFuel Consumption Expected 10.6km/l in 2.4l Engine.

Few details on GDI Engines which are already in use

Performance comparison between MPI and GDI engine

CFD Modeling of the Flow

o Software used Fluent (By ANSYS) GAMBIT

Cylinder specification used in the modeling

Bore x Stroke 88 x 97Compression Ratio 10.5 , 12

Displacement 2.4L (4 Cylinder)

Injector Piezo-actuated outwardly-opening type

Piston Curved top

Actuation Piezo

Type Outward-Opening

Nominal Spray Cone Angle 900

Static Flow Rate More than 35 g/s

Fuel Pressure Range 100-200 bar

CFD Modeling Procedure

oDrawing the Cylinder and Other engine components Using Gambit

oMeshing the Combustion cylinder using GAMBIT

oImporting the Geometry to ANSYS Fluent

oDefining the necessary boundary conditions for the combustion cylinder

oSolving the flow using Fluent1. Solving the flow equations for air and fuel flow 2. Solving the energy equation for combustion and heat transfer

o Generation of Graphical images and graphs for the simulation

Example Flow Model of a MPFI Engine for learning purpose

Example Flow Model of a MPFI Engine for learning purpose

Example Flow Model of a MPFI Engine for learning purpose

The meshing of the 2D Engine Geometry

3D Cylinder development in GAMBIT

The End

References-

oSAE technical paper series

oWiki-Pedia (www.wikipedia.org)

oHyundai Motors Website