A characteristic study and optimization of in-cylinder configuration for particulate matters reduction in an off-highway diesel engine with mechanical fuel injection system

Abstract

This paper shows development challenges for 11-liter heavy-duty off-highway diesel engines to meet Tier 3 emission regulations with a base diesel engine compliant with Tier 2 emission regulations. In the case of the installation of an exhaust gas recirculation (EGR) system for reduction of NOx emissions, there exists a risk of increased particulate matters (PM) emissions. An in-cylinder PM reduction is still necessary since a diesel particulate filter (DPF) after-treatment system is not under the consideration. The objective of this research is to see whether the base engine has a potential to meet Tier 3 emission regulations by changing in-cylinder configuration parameters including the bowl shape, injector position, the number of intake and exhaust valves, injector tip protrusion, and injector tip specifications such as nozzle spray angle and nozzle flow rate. These parameters are very important parts which enhance the air and fuel mixing process that helps the combustion process. Thus, the optimization of these design variables is essential to improve combustion efficiency and emissions reduction. In this study, the multi-dimensional computational fluid dynamics (CFD) code KIVA-3V is used to perform combustion simulations. The Kelvin–Helmholtz/Rayleigh–Taylor (KH-RT) model is employed for spray breakup and a reduced chemical mechanism for n-heptane is employed to simulate ignition delay and combustion of diesel fuel. To verify the simulation results, engine bench tests were performed with installations of the final version of in-cylinder geometry in C1-8 mode which is one of main test cycles to meet Tier 3 emission regulations. Finally, Tier 3 emission regulations have been met with the currently optimized in-cylinder configuration parameters.

Design of experiments to investigate blade geometric effects on the hydrodynamic performance of torque converters

“…Three 2 6 full factorial designs were conducted on each component to determine the main effect and all the possible interaction effect. The main performance indices are (a) stall torque ratio ( TR 0 = TT 0 / TP 0 ), which indicates the launching performance, (b) stall capacity constant ( C 0 = TP 0 • ω P −2 • D −5 ), which refers to power density, and (c) peak efficiency ( η max ), which is an index for fuel economy.…”

“…Design of experiments (DOE) and statistical regression techniques are able to explore the relationship and approximate the unknown function with limited samples. Thus, much research has been done on the coupling of CFD and DOE in the design of turbomachines, 2,3 blades, 4 engine, 5,6 and other automobile applications. 7 Song et al 8 developed a torque converter design optimization system, which integrated blade geometry design, CFD simulation, and optimization to simplify the design process for torque converters.…”

Engine-out emissions from a modern high speed diesel engine – The importance of Nozzle Tip Protrusion

“…Miles and Andersson [19] state that NTP itself is not often studied directly, rather as a calibration parameter for differing spray angles, but note that deeper NTP is likely to increase injector tip temperature. NTP is often mentioned as a calibration parameter [20][21][22], for example Tonetti et al discuss calibrating with NTP in their work [22], however comprehensive studies of the effect of NTP are rare. Given that this is a parameter which could be sensitive enough to be affected by manufacturing tolerances, or changed during a vehicles service life (for example during a fuel injector change) there is a need to explore in depth the impact of NTP in a modern diesel engine.…”