Effect of piston shape design on the scavenging performance and mixture preparation in a two-stroke boosted uniflow scavenged direct injection gasoline engine

Abstract

Compared to a four-stroke engine, the two-stroke engine doubles firing frequency and has favourable power-to-weight or power-to-volume ratio as well as engine downsizing to improve the overall powertrain fuel economy. In order to overcome the shortcomings of the conventional cross-flow or loop scavenged two-stroke engines, a two-stroke boosted uniflow scavenged direct injection gasoline engine was designed and its performance was analysed. In this study, three-dimensional computational fluid dynamics simulations were performed to understand the impact of the piston shape design on the scavenging process, in-cylinder flow formation, turbulence level and subsequent fuel/air mixing process in the boosted uniflow scavenged direct injection gasoline engine. Both single injection and split injection strategies were investigated to study the interactions between piston designs and fuel injection strategies to achieve stoichiometric mixture around the spark plug. The results show that the optimised piston with the same opening timing for all scavenge ports could achieve much better scavenging performance than the baseline piston design. In particular, the shallow pistons, that is, Piston #1 and Piston #4, could produce stoichiometric mixture around the spark plug with relatively lower inhomogeneity and higher turbulence kinetic energy around top dead centre when implementing the split injection strategy with start of injection timing at 250/310 °CA.

Analysis of a novel concept of 2-stroke rod-less opposed pistons engine (2S-ROPE): Testing, modelling, and forward potential

“…On the other hand, new engine concepts pursue accomplishing the latest fuel consumption and emissions requirements [9]. Some innovative engine configurations are gasoline 2-stroke direct injection engines [10] and two stroke opposed piston engines [11]. It is this line where this study contributes with a new 2-stroke Rodless Opposed Pistons Engine (2S-ROPE) concept.…”

Numerical study on the effects of intake charge on oxy-fuel combustion in a dual-injection spark ignition engine at economical oxygen-fuel ratios

“…Nowadays, Gasoline Direct Injection (GDI) technology has been widely adopted as a common engine configuration and a hot spot on the academia and industry. [30][31][32][33][34][35] In 2005, an advanced technology named dual-injection, which schematic is shown in Figure 2, was commercially applied to SI engines by Toyota. 36 With the combination of GDI and PFI's advantages, dual-injection technology of SI engine has attracted more researchers in recent years.…”

“…23][24][25][26][27][28][29] applied ICRC method to practical Port Fuel Injection (PFI) SI engines fuelled with propane under operating conditions of oxygen volume fraction from 40% to 55%. These studies revealed that engine performance under OFC mode could be improved by optimising operating parameters, such as oxygen fraction, water injection, etc.Nowadays, Gasoline Direct Injection (GDI) technology has been widely adopted as a common engine configuration and a hot spot on the academia and industry[30][31][32][33][34][35]. In 2005, an advanced technology named dual-injection, which schematic is shown in Figure2compression ratio and boost level can be achieved due to effective knock suppression.…”

Effects of Water Injection Strategies on Oxy-Fuel Combustion Characteristics of a Dual-Injection Spark Ignition Engine

“…However, few studies have been reported about the implementation of OFC in GDI engines or dual-injection SI engines. However, Gasoline Direct Injection (GDI) technology has become the mainstream of SI engines in academia and industry [27][28][29][30][31][32][33][34][35]. In 2005, an advanced technology named dual-injection was commercially applied to SI engines by Toyota [36].…”