1. Next Generation SI Engines : GDI Internal Combustion Engines
P M V Subbarao
Professor
Mechanical Engineering Department
I I T Delhi
New & Better Anatomy of Artificial Horse …..

2. Evolution of Fuel Inductions Systems in SI Engines

3. 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.

4. High End 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.

5. Structure of GDI Engine

6. In-Cylinder Flow Geometry of A GDI Engine
Injection of gasoline directly inside the cylinder at high pressure.
Enhanced evaporation and mixing are facilitated through turbulent flow inside the cylinder.
Can generate homogeneous or stratified mixture.
Ultra lean mixtures can be used.
A Comprehensive use of Advanced Fluid Mechanics in the design and development of IC engines.

7. Objectives for the development of GDI engine
Very high fuel economy
Superior power output  than MPFI engine
Acceptable levels of emissions
GDI is basically a combination of CI & SI engines.

8. 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

9. Challenges in developing DGI 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 like penetration and spray angle are crucial for the correct operation of the engine.

10. Challenging Fluid Mechanics of Fuel Admission
GDI : 50 – 100 bar
Multi Poin Injection : ~ 5 bar
Injection Pressure
Single Point Injection 2 – 3 bar
Carburetor : 20 – 50 Pa
Technology of Fuel Admission

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

12. Performance of GDI power Fuel economy MPI engines GDI engine
Carburetor
GDI engine
Diesel engine
MPI engine
A/F ratio
Fuel economy
MPI engines
power

13. Clues to Enhance Turbulence in Cylinder

14. Swirl based systems

15. Squish based GDI concepts

16. Tumble based GDI systems

17. Generation of Stratified A/F Mixture

18. Critical Design Issues : GDI

19. How to develop Design Knowledge???

20. Thermodynamic Modeling : Development of Pseudo GDI Engine
Modeling of IC engine process can be carried out in many ways.
Multidimensional, Transient Flow and heat transfer Model.
Thermodynamic Transient Model USUF.
Fuel-air Thermodynamic Model.
Air standard Thermodynamic Model