Next Generation SI Engines GDI Internal Combustion Engines
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 k. W@ 6000 : 140 Nm at 3500 rpm : CR=11: 1. • BMW Z 4/528 i: Twin Power Turbo Inline 4 cyl. 16 Valve: 1997 CC: 180 k. W@ 5000 rpm: 10. 0 : Fuel economy: 5. 9/8 --/8. 8 l/100 km. • 2017 Kia Sportage SX Turbo 2. 4 L : In-line 4 cyl. DOHC GDID-CVVT 16 valve : 2, 359 CC : 135 k. W @ 6, 000 rpm: 237 Nm@4000 rpm : CR=11. 3 : Fuel economy: 6. 7/8. 5/11. 8 l/100 km.
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 • • ü ü ü • • • 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 Injection Pressure GDI : 50 – 100 bar Multi Poin Injection : ~ 5 bar Single Point Injection 2 – 3 bar Carburetor : 20 – 50 Pa Technology of Fuel Admission
Fluid Mechanics of Fuel Admission Droplet size GDI : 20 – 50 mm Multi Poin Injection : ~ 200 mm Single Point Injection 100 – 300 mm Carburetor : 1 ~ 3 mm Technology of Fuel Admission
Performance of GDI engine power MPI engines Carburetor GDI engine Fuel economy Diesel engine MPI engine Carburetor A/F ratio
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
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