Effect of Fuel Spray Geometries on Diesel Combustion Characteristics for Developed Combustion Chamber

This study investigates the effect of geometries of fuel spray on diesel combustion characteristics, i.e., ignition lag (IL) for diesel engines. The IL is measured for two nozzle spray designs, i.e., hollow conical spray (HCS) and solid conical spray (SCS). Various cylinder air pressures (CAP), hot surface temperatures (HST), and injection pressures (IP) are considered operating parameters. An exper-imental setup is fabricated for testing and analysis to reduce IL. The IL for the fuel sprays is recorded through an oscilloscope based on the time lag between the incidents of injection and the presence of flame inside the combustion chamber. The results show that the IL for HCS is (4.9 ms) lesser than SCS (5.2 ms), corresponding to minimum IP, maximum AP and HST. The IL decreases by changing the IP from 100 to 200 bar for HCS and SCS. The increasing HST from 350 to 550 °C and CAP from 15 to 25 bar provide reduced IL. The IL with HCS is 6.12% lower than the SCS. However, the maximum IL of 36.6 ms is obtained by solid conical spray whereas 32.6 ms by HCS corresponds to same parameters i.e. minimum values of HCS, IP, and CAP. The findings show that the hollow conical spray design is more suitable for the diesel engine considering the fuel saving, smooth functioning, and other combustion characteristics.