Effect of Swirl Ratio and Piston Geometry on the Late-Compression Mean Air-Flow in a Diesel Engine
Abstract
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. A realistic bowl geometry was modeled and simulated using CONVERGE under non-firing conditions to study the flow dynamics. These results were validated with the flow-field of a light-duty optical engine, obtained through Time-Resolved Particle Image Velocimetry (TR-PIV). Further, simulations were carried out using two different bowl geometries. The effect of variations in geometry on turbulent kinetic energy (TKE) was investigated.