1. Analysis of GDI Internal Combustion Engines as Automobile Prime Movers
P M V Subbarao
Professor
Mechanical Engineering Department
I I T Delhi
Avoid HC Escape Routes & Promote High CR…..

2. What is A GDI Engine?
Injection of gasoline directly inside the cylinder at high pressure.
Entire mixing is facilitated through turbulent flow inside the cylinder.
Can generate homogeneous or stratified mixture.
Ultra lean mixtures can be used.
A complete utilization of Fluid Mechanics in the design and development of IC engines.

3. Flammability Vs Inflammability Characteristics

4. Operating modes of the GDI engine
Superior output mode
Injection in late intake stroke
Wider spray with high penetration for charge homogenization
A/F – Stoichiometric
Homogeneous A-F Mixture
Complete Vaporization of Fuel
Ultra Lean combustion mode
Very lean stratified mixture : A/F ~ 30
Injection during compression
Compact spray, deflected from the piston top to the spark plug
Distinct Stratification
At spark , ignitable mixture conditions
It is two engines in one place

5. Automobiles with GDI I.C. Engine
1999 Mitsubishi Mirage 1500 GDi Dingo Pearl : Naturally aspirated petrol Engine Inline 4 cyl.1468 cc : DOHC : 16 valves : :140 Nm at 3500 rpm : CR=11:1.
BMW Z4/528i: Twin Power Turbo Inline 4 cyl. 16 Valve: 1997CC: 5000rpm: 10.0 : Fuel economy: 5.9/8--/8.8 l/100km.
2017 Kia Sportage SX Turbo 2.4L : In-line 4 cyl. DOHC GDI- D-CVVT 16 valve : 2,359CC : 6,000rpm: : CR=11.3 : Fuel economy: 6.7/8.5/11.8 l/100km.

6. Objectives for the development of GDI engine
Very high fuel economy
Superior power output  than MPFI engine
Acceptable levels of emissions
It is basically a combination of two engines.

7. Challenges in developing GDI Engine
The fuel injection to the cylinder should meet two requirements.
First one, it should enable the homogeneous charge burning.
Secondly, It should also enable obtaining a lean mixtures close to cylinder walls.
The injection system must allow for any quantitative and qualitative formation of the charge and affect the way it is later burnt.
The macroscopic characteristic of fuel injection spray for SI DI engines like penetration and spray angle are crucial for the correct operation of the injection system.

8. Major Strategies for GDI
Wall Guided GDI system (WGGDIS)
Spray Guided GDI System(SGGDIS)
Air Guided GDI System (AGGDIS)

9. WGGDIS : Geometry of Cylinder & In-cylinder Flow
Carburetor Era : Flat piston & Flat Cylinder --- Wedge shaped cylinder with flat piston.
SPI & MPI Era : Wedge shaped cylinder head --- special manifold for generation more turbulence – Optimized location of spark plug.
GDI Era : To design entire cylinder, piston and manifold geometry using computational and experimental fluid mechanics.
More the use of Fluid Mechanics, the better will be the engine.
Three dimensional turbulent flow simulation will be culmination of IC Engine Development.

10. Various Cylinder Configurations for GDI concept

11. Swirl based systems

12. Squish based GDI concepts

13. Tumble based GDI systems

14. Squish based GDI concepts

15. Generation of Stratified A/F Mixture

16. SGGDIS : Fluid Mechanics of Fuel Admission - 1
GDI : 50 – 100 bar
Multi Poin Injection : ~ 5 bar
Driving Pressure
Single Point Injection 2 – 3 bar
Carburetor : 20 – 50 Pa
Technology of Fuel Admission

17. SGGDIS : Fluid Mechanics of Fuel Admission -2
GDI : 20 – 50 mm
Multi Poin Injection : ~ 200mm
Single Point Injection 100 – 300mm
Droplet size
Carburetor : 1 ~ 3 mm
Technology of Fuel Admission

18. AGGDIS Technologies Tumbling Flow Tumbling Port
Hollow Cone Spray Generated Air Motion
Hollow Cone Spray
Tumbling Flow

19. Induction of Global Vortex Motion in Engine Cylinder

20. Performance of GDI Power/weight Fuel economy MPI engines GDI engine
Carburetor
GDI engine
Diesel engine
MPI engine
A/F ratio
Fuel economy
MPI engines
Power/weight

21. Expected Characteristics of the GDI Engine
High Compression ratio
Precise control over Air/Fuel distribution inside the combustion chamber
Improved volumetric efficiency

22. Swirl based systems