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Journal Article

Effect of Engine Parameters on Mixture Stratification in a Wall-Guided GDI Engine - A Quantitative CFD Analysis

2017-03-28
2017-01-0570
Today, GDI engines are becoming very popular because of better fuel economy and low exhaust emissions. The gain in fuel economy in these engines is realized only in the stratified mode of operation. In wall-guided GDI engines, the mixture stratification is realized by properly shaping the combustion chamber. However, the level of mixture stratification varies significantly with engine operating conditions. In this study, an attempt has been made to understand the effect of engine operating parameters viz., compression ratio, engine speed and inlet air pressure on the level of mixture stratification in a four-stroke wall-guided GDI engine using CFD analysis. Three compression ratios of 10.5, 11.5 and 12.5, three engine speeds of 2000, 3000 and 4000 rev/min., and three inlet air pressures of 1, 1.2 and 1.4 bar are considered for the analysis. The CONVERGE software is used to perform the CFD analysis. Simulation is done for one full cycle of the engine.
Technical Paper

Effect of Fuel Injector Location and Nozzle-Hole Orientation on Mixture Formation in a GDI Engine: A CFD Analysis

2018-04-03
2018-01-0201
Gasoline direct injection (GDI) engines have gained popularity in the recent times because of lower fuel consumption and exhaust emissions compared to that of the conventional port fuel injection (PFI) engine. But, in these engines, the mixture formation plays an important role which affects combustion, performance and emission characteristics of the engine. The mixture formation, in turn, depends on many factors of which fuel injector location and orientation are most important parameters. Therefore, in this study, an attempt has been made to understand the effect of fuel injector location and nozzle-hole orientation on the mixture formation, performance and emission characteristics of a GDI engine. The mixture stratification inside the combustion chamber is characterized by a parameter called “stratification index” which is based on average equivalence ratio at different zones in the combustion chamber.
Technical Paper

Effect of Mixture Distribution on Combustion and Emission Characteristics in a GDI Engine - A CFD Analysis

2017-09-04
2017-24-0036
Mixture distribution in the combustion chamber of gasoline direct injection (GDI) engines significantly affects combustion, performance and emission characteristics. The mixture distribution in the engine cylinder, in turn, depends on many parameters viz., fuel injector hole diameter and orientation, fuel injection pressure, the start of fuel injection, in-cylinder fluid dynamics etc. In these engines, the mixture distribution is broadly classified as homogeneous and stratified. However, with currently available engine parameters, it is difficult to objectively classify the type of mixture distribution. In this study, an attempt is made to objectively classify the mixture distribution in GDI engines using a parameter called the “stratification index”. The analysis is carried out on a four-stroke wall-guided GDI engine using computational fluid dynamics (CFD).
Technical Paper

Numerical Investigation of the Impact of Fuel Flow Rate on Combustion in a Heavy-Duty Diesel Engine with a Multi-Row Nozzle Injector

2022-03-29
2022-01-0395
Diesel engines are one of the most popular combustion systems used in different types of heavy-duty applications because of higher efficiencies compared to the spark ignition engines. Combustion phasing and the rate of heat release in diesel engines are controlled by the rate at which the fuel is injected into the combustion chamber near top dead center. In this work, computational fluid dynamics (CFD) was employed to simulate the combustion behavior of a heavy-duty diesel engine equipped with a 16-hole injector, in which the nozzles were arranged in two individual rows. The two rows of nozzles have differential flow rate due to the geometrical construction of the injector. Combustion and performance characteristics of the engine were compared with and without considering the differential flow rate of the nozzle rows at a range of injection timing values.
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