Research Projects

Reciprocating internal combustion engines will remain relevant in the transport sector for the next 10-20 years despite the emergence of battery electric and fuel cell electric vehicles. Consistent improvement in engine efficiency, fuel economy, and emission levels should be a priority for the next decade. As per NITI Aayog estimate, gasoline engine vehicles will have considerable shares in the transportation sector in India. The gasoline direct injection (GDI) systems involve directly introducing the fuel spray inside the engine at much higher pressures (~ 200-300 bar) compared to the port-fuel injection (PFI) used in SI engines. In the recent past, a few studies from research groups outside India have explored even higher pressures in the range of 700-1500 bar. When the injection pressure is high, the fuel is atomized better, leading to better charge preparation/air-fuel mixing. As a result, the performance of the combustion is improved and the emissions are lowered. In order to improve engine efficiency and fuel economy, there is a recent trend of engine-downsizing and turbo-charging. However, during engine idling conditions, the fuel evaporation levels get reduced and chances of spray-wall interactions arise. Spray-wall interaction adversely affects fuel economy, resulting in excess soot and unburned hydrocarbons (UHC). As a result, meeting particulate number (PN) regulations is challenging. Thus, studying spray-wall impingement for GDI engines is critical for making engine operation more environmentally friendly. Comprehensive parametric studies, both numerical and experimental, in the spray-wall impingement area of a GDI system are still limited and for alternative fuels such studies are rarely reported. In terms of numerical studies of GDI spray-wall interactions, effect of internal nozzle flow is never reported. In GDI spray modeling literature, it has been shown that internal nozzle flow plays a crucial role for free sprays (without wall impingement). Therefore, it will be very meaningful to investigate the role of an internal nozzle flow on the spray-wall interaction in a GDI system. The experimental findings will be critical to numerical modeling for the model validation and further parametric studies. The experimental study will involve the spray impingement of different pure and blended fuels on a flat plate with a varying distance from the point of injection to resemble the actual engine-like conditions. The experimental images will be used to measure the film thickness, spray spread using a diffuse back-illumination (DBI) technique. On the other hand, the numerical work validates the model with different turbulence models for the following experimental findings of spray-wall interaction in a GDI system to optimize injection and chamber conditions better. The fuels tested will be gasoline, ethanol and gasoline-ethanol blends. In- house codes will be developed for post-processing the results from experiments and CFD.