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Better understanding of flow phenomena inside the combustion chamber of a diesel engine and accurate measurement of flow parameters is necessary for engine optimization i.e. enhancing power output, fuel economy improvement and emissions control. Airflow structures developed inside the engine combustion chamber significantly influence the air-fuel mixing. In this study, in-cylinder air flow characteristics of a motored, four-valve diesel engine were investigated using time-resolved high-speed Tomographic Particle Imaging Velocimetry (PIV). Single cylinder optical engine provides full optical access of combustion chamber through a transparent cylinder and flat transparent piston top. Experiments were performed in different vertical planes at different engine speeds during the intake and compression stroke under motoring condition. For visualization of air flow pattern, graphite particles were used for flow seeding.

The world energy demand has witnessed uncertainties in two dimensions. The scarcity and depletion of conventional petroleum sources are causes of great concern worldwide. Combustion of fossil fuels has led to unprecedented rise in the global CO2 level, leading to global warming. Therefore, efforts are underway in several countries to search for suitable alternative fuels that are environment friendly. Vegetable oils of non-edible nature are such alternative fuels, which can form part of potential solution. Vegetable oils, due to their agricultural origin, are able to reduce CO2 emissions to the atmosphere along with import substitution of petroleum products In the present research, experiment were designed to study the effect of reducing Neem oil's high viscosity by increasing the fuel temperature and thereby its effect on combustion and emission characteristics of the engine.

IC engines are facing two major challenges in the 21st century namely threat of fossil fuel depletion and environmental concerns. HCCI engine is an attractive solution to meet stringent emission challenges due to its capability to simultaneously reduce NOx and PM. HCCI technology can be employed with different alternative fuels without significant modifications in the existing engines. In this study, HCCI combustion was investigated using B20 (20% v/v biodiesel with diesel). Investigations were carried out on a two cylinder engine, in which one cylinder was modified to operate in HCCI mode however the other cylinder operated in conventional CI combustion mode. A dedicated fuel vaporizer was used for homogeneous fuel-air mixture preparation. The experiments were performed at three different intake charge temperatures (160°C, 180°C and 200°C) and three different EGR ratios (0%, 10% and 20% EGR) at different engine loads.

Premixed charge compression ignition (PCCI) combustion is an advanced combustion technique, which has the potential to be operated by alternative fuels such as alcohols. PCCI combustion emits lower oxides of nitrogen (NOx) and particulate matter (PM) and results thermal efficiency similar to conventional compression ignition (CI) engines. Due to extremely high heat release rate (HRR), PCCI combustion cannot be used at higher engine loads, which make it difficult to be employed in production grade engines. This study focused on development of an advanced combustion engine, which can operate in both combustion modes such as CI combustion as well as PCCI combustion mode. This Hybrid combustion system was controlled by an open engine control unit (ECU), which varied the fuel injection parameters for mode switching between CI and PCCI combustion modes.