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…..

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.

Flammability Vs Inflammability Characteristics

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

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 : 78 kW@ 6000 :140 Nm at 3500 rpm : CR=11:1. BMW Z4/528i: Twin Power Turbo Inline 4 cyl. 16 Valve: 1997CC: 180kW@ 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 : 135kW @ 6,000rpm: 237Nm@4000rpm : CR=11.3 : Fuel economy: 6.7/8.5/11.8 l/100km.

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.

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.

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

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.

Various Cylinder Configurations for GDI concept

Swirl based systems

Squish based GDI concepts

Tumble based GDI systems

Squish based GDI concepts

Generation of Stratified A/F Mixture

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

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

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

Induction of Global Vortex Motion in Engine Cylinder

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

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

Swirl based systems