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In this study, 3D air-flow-field evolution in a single cylinder optical research engine was determined using tomographic particle imaging velocimetry (TPIV) at different engine speeds. Two directional projections of captured flow-field were pre-processed to reconstruct the 3D flow-field by using the MART (multiplicative algebraic reconstruction technique) algorithm. Ensemble average flow pattern was used to investigate the air-flow behavior inside the combustion chamber during the intake and compression strokes of an engine cycle. In-cylinder air-flow characteristics were significantly affected by the engine speed. Experimental results showed that high velocities generated during the first half of the intake stroke dissipated in later stages of the intake stroke. In-cylinder flow visualization indicated that large part of flow energy dissipated during the intake stroke and energy dissipation was the maximum near the end of the intake stroke.

Fuel-air mixing is the main parameter, which affects formation of NOx and PM during CI combustion. Hence better understanding of air-flow characteristics inside the combustion chamber of a diesel engine became very important. In this study, in-cylinder air-flow characteristics of four-valve diesel engine were investigated using time-resolved high-speed tomographic Particle Imaging Velocimetry (PIV). For visualization of air-flow pattern, fine graphite particles were used for flow seeding. To investigate the effect of different operating parameters, experiments were performed at different engine speeds (1200 rpm and 1500 rpm), intake air temperatures (room temperature and 50°C) and intake port configurations (swirl port, tangential port and combined port). Intake air temperature was controlled by a closed loop temperature controller and intake ports were deactivated by using a customized aluminum gasket.

The rising concerns of emissions have put enormous strain on the automotive industry. Industry is, therefore looking for next-generation engines and advanced combustion technologies with ultra-low emissions and high efficiency. To achieve this, more insights into the combustion and pollutant formation processes in IC engines is required. Since conventional measures have not been insightful, in-situ measurement of combustion and pollution formation through optical diagnostics is being explored. Gaining full optical access into the diesel engine combustion chamber is a challenging task. The late-compression flow dynamics is not well understood due to limited access into the engine combustion chamber. These flow structures contribute immensely to fuel-air mixing and combustion. The objective of this study is to understand the role of combustion chamber design on vertical plane air-flow structures.