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In order to achieve good fuel spray characteristics, proper placing of the fuel injector in the intake manifold in port fuel injected (PFI) gasoline engines is very crucial. In automotive PFI engines, vehicle layout may be a constraint to mount the fuel injector in best possible location and inclination. In general, PFI engines use straight spray fuel injection. However, if there is a vehicle layout constraint, then inclined fuel spray may be suitable which is not very common. Hence, it is important to understand the effect of fuel spray inclination on fuel spray characteristics. In this study, a CFD analysis has been carried out for the four inclinations of fuel spray and the results are compared. The geometrical modeling of the fuel injector is done using ProE software. It is meshed with polyhedral cells and mesh refinement is done wherever required. Inlet air velocity and exit pressure of intake pipe at wide-open-throttle conditions are used as boundary conditions.

In modern direct injection gasoline engines, air-fuel mixing has a strong influence on combustion and emission characteristics, which in turn largely depends on in-cylinder fluid motion. However, in-cylinder fluid motion dependent on many engine parameters viz., piston shape, engine speed, intake manifold orientation, compression ratio, fuel injection timing, duration, etc. Among them, piston shape has significant influence on the in-cylinder fluid motion. Therefore, this study aims on evaluating the effect of piston shape on in-cylinder flows in a direct injection engine using CFD. In this study, a single-cylinder, two-valve, four-stroke direct injection engine designed for two-wheeler application in India is considered for the analysis. ‘STAR-CD’ and és-ice’ are used for CFD analysis. Pressure boundary values obtained from measurements in the actual engine are employed. Two piston-shapes viz., flat and bowl types at wide-open-throttle under non-firing conditions are considered.

With the introduction of stringent emission norms for two wheeler applications, and need to reduce green house gases emission, it is a challenging task to improve the performance of the engine, especially at part throttle conditions. The typical drawback of spark ignition engine is poor part throttle performance and the Indian driving cycle (IDC) predominantly covers these part throttle operations. Contrary to popular belief, carbureted two wheelers with engine capacity up to 250cc are able to meet regulation Euro III with add-ons like secondary valve and catalyst. Vehicles with EFI systems are more expensive and they are not able to provide any fuel economy benefit or improvement in drivability. Under these circumstances, carburetor designers are working continuously to improve its performance. In order to improve the performance, optimization of slow speed to high speed fueling circuit dividing ratio is of immense importance.

The main challenge in designing the oil pump for gasoline & diesel engines is to optimize the pressure relief passage. Pressure relief passage is critical from design point of view as it maintains the oil pressure in the engine. Optimal levels of oil pressure and flow are very important for satisfactory performance and lubrication of various engine parts. Low oil pressure will lead to seizure of engine and high oil pressure leads to failure of oil filters, gasket sealing, etc. Optimization of pressure relief passage area will also reduce the power consumed by the pump. The Pressure relief system for this study consists of Pressure relief valve, spring, retainer, pressure relief passages. It is difficult to directly measure the flow through the pressure relief passage and is arrived based on the drop in flow at the delivery port. Numerical tool will be handy to predict the flow through the pressure relief passage and this can be used to optimize the flow through the bypass passage.

The main challenge in today's modern engines is to design the parts, which should withstand higher temperatures. To achieve this, selection of materials and process tolerances are very important factors. The product identified in this study is a conventional oil pump, which is an engine auxiliary component. The function of the oil pump is to supply oil to different parts of the engine to lubricate and reduce the overall engine friction. The different speed and load conditions for which the engine is subjected, pose a challenge to the oil pump, to supply the necessary quantity of oil at the required pressure and temperature. Normally, the oil pump is subjected to a temperature of 120°C at higher speeds. However, the peak oil temperature in modern diesel engines can be as high as 140°C to 150°C for a short period of time. For this study, two engine grade oils were selected. Numerical analysis was performed to predict the oil flow rate for these oil grades.

In India, for two-wheeler application, carburettor is the preferred fuel supply system for majority of the market, owing to its simplicity and low cost. With the regulations becoming stringent, carburettor internal structure requires modification. One of the important parameters is the venturi shape, which controls the air-fuel mixture supply to the engine. Venturi shape plays an important role in deciding the transient performance characteristics. In this study, a CFD analysis has been carried out to predict the pressure and velocity at the venture of the carburettor. Four different cross sections namely, circular, oval, trapezoidal and double D venturi shapes were selected. The geometric model of the carburettor was created and mesh refinements were carried out in critical regions. At part open throttle, CFD prediction of airflow rate with Trapezoidal venturi shape was found higher when compared to other venturi shapes.

Emerging trend in the automotive industry all around the world is to develop vehicles to consume less fuel and to meet stringent emission norms by using engines of higher power to weight ratio and higher thermal efficiency. These advanced technology engines designed for high power output will use low viscous oil to reduce frictional losses and will operate at elevated temperature levels. Hence, the various auxiliaries and parts of these engines should be adaptable for the use of low viscous oil and should withstand higher temperatures. Oil pump is one such auxiliary which will be subjected to work with low viscous oil at higher temperatures levels. The oil pump taken for study and design improvement is an internal gear type positive displacement oil pump, used in a passenger car diesel engine. The un-meshing of the gears causes the inflow and meshing causes the outflow of lubricating oil. This process occurs continuously for providing a smooth pumping action.

In gasoline direct injection (GDI) engines, air-fuel mixture homogeneity plays a major role on engine performance, especially in combustion and emission characteristics. The performance of the engine largely depends on various engine operating parameters viz., start of injection, duration of injection and spark timing. In order to achieve faster results CFD is becoming a handy tool to optimize and understand the effect of these parameters. Therefore, this study aims on evaluating the two injection parameters viz., single and split injection to evaluate different flame characteristics. Novelty in this study is to define five different parameters which are called α, β, γ, δ and η the details of which are explained in the paper. In order to understand the flame characteristics, these five parameters are found to be very useful. In the present study, a single-cylinder, two-valve, four- stroke engine which is used in two-wheelers in India is considered for carrying out the CFD analysis.

Gasoline direct injection (GDI) technology is already in use in four wheeler applications owing to the additional benefits in terms of better combustion and fuel economy. The air-assisted in-cylinder injection is the emerging technology for gasoline engines which works with low pressure injection systems unlike gasoline direct injection (GDI) system. GDI systems use high pressure fuel injection, which provides better combustion and reduced fuel consumption. It envisages small droplet size and low penetration rate which will reduce wall wetting and hydrocarbon emissions. This study is concerned with a CFD analysis of an air-assisted injection system to evaluate mixture spray characteristics. For the analysis, the air injector fitted onto a constant volume chamber (CVC) maintained at uniform pressure is considered. The analysis is carried out for various CVC pressures, mixture injection durations and fuel quantities so as to understand the effect on mixture spray characteristics.