Document Type : Research Paper
Authors
1 Mianeh technical and engineering faculty, University of Tabriz, Mianeh, Iran
2 Department of Mechanical Engineering, Parand Branch, Islamic Azad University, Parand, Iran
Abstract
Increasing the power and improving the performance of diesel engines is always considered by diesel engine manufacturers. Changing the geometry of the injector outlet orifice has major impact on fuel-air mixing and combustion. In the current study, geometry of the injector orifice is changed from circular to annular cross-section, and the effect of different injection pressures on diesel engine performance is investigated. All numerical simulations are performed by using AVL Fire code. The results show that the annular injector improves combustion and engine performance by forming better fuel distribution. Fuel injection pressure affects the performance of the annular injector in terms of droplets distribution and breakup. At low injection pressures, due to the long injection duration, most of the fuel energy release occurs after top dead center (TDC). Therefore, the engine performance is improved, and the combustion chamber temperature and pressure are limited. However, at high injection pressures, less combustion occurs after TDC. By changing the injector geometry to the injector with annular cross-section orifice, the maximum reduction in SFC value is for case P5 and injection durations 10 degrees, which is decreased by 21.4%. In the studied cases, the maximum power increase was 15% for a 2.5% increase of fuel at injection pressure of 100MPa. While NO pollutant increased slightly by changing the type of injector at different injection pressures, the soot produced at the beginning of the combustion process is well oxidized before the end of the work phase, and its amount reached less than 2e-6.
Graphical Abstract
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Keywords
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