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 …..

Evolution of Fuel Inductions Systems in SI Engines

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.

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 : 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.

Structure of GDI Engine

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.

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.

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

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.

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

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

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

Clues to Enhance Turbulence in Cylinder

Swirl based systems

Squish based GDI concepts

Tumble based GDI systems

Generation of Stratified A/F Mixture

Critical Design Issues : GDI

How to develop Design Knowledge???

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