Analysis of the Effect of Intake Plenum Design on the Scavenging Process in a 2-Stroke Boosted Uniflow Scavenged Direct Injection Gasoline (BUSDIG) Engine

Abstract

In this study, the effect of the intake plenum design on the scavenging process in a newly proposed 2-stroke Boosted Uniflow Scavenged Direct Injection Gasoline (BUSDIG) engine was studied in detail by three dimensional (3D) computational fluid dynamics (CFD) simulations. In the BUSDIG engine, the intake scavenge ports are integrated into the cylinder liner and their opening and closure are controlled by the movement of piston top while exhaust valves are placed in the cylinder head. In order to accommodate the optimized scavenge ports in the real engine application, the intake plenum with an inlet pipe and a scavenge chamber was designed and connected to the 12 evenly distributed scavenge ports in a single cylinder BUSDIG engine. In order to achieve optimal scavenge performances and sufficient in-cylinder flow motions to enhance the fuel/air mixing, five design parameters of the intake plenum were investigated, including the ratio of the inlet area relative to the scavenge port area (r I/S ), the radius of the round connecting the inlet pipe and the scavenge chamber (r R ), the ratio of the scavenge chamber volume to the cylinder displacement volume (r S/C ), the angle between the inlet pipe and exhaust pipe (α I/E ) and the ratio of bore to the scavenge port length (r B/PL ). It is found that the best scavenging performance is achieved at low engine speed when the intake plenum design shows less impact on the scavenging performances. As the engine speed increases, the impact on the scavenging performance by the intake plenum design becomes more significant. There is a trade-off between the tumble ratio (TR) and cross tumble ratio (CTR) for each intake plenum design. Based on the systematic study carried out, the intake plenum design parameters were optimized for high scavenging performance and strong large scale flow motions in the BUSDIG engine.

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

“…The centrally mounted DI injector and spark plug on the cylinder head were positioned to place the spray recirculation region around the spark plug. The key engine design parameters, including engine bore/stroke ratio, 39 scavenge port angles, 40–42 opening profiles of scavenge ports and exhaust valves 43 and intake plenum, 44 have been analysed and evaluated for optimal scavenging performance and in-cylinder flow motions. A full review of the BUSDIG engine concept can be found in a recently published article.…”

Analysis of Different Uniflow Scavenging Options for a Medium-Duty 2-Stroke Engine for a U.S. Light-Truck Application

“…Some of these mechanisms afford the potential to realize variable timing of the exhaust versus the intake, with the ability to control combustion through homogeneous charge compression ignition-type combustion systems, e.g. the portpoppet engine which in production form has already used electrohydraulic continuously-variable exhaust valve control [10,16] and for which exhaust cam profile switching has been proposed for automotive use [17]. Also, partly because of the improved bore distortion performance mentioned above, all of those engines used as examples employed or employ a wet sump lubrication system, which in theory could permit oil consumption levels approaching those of 4-strokes [2], and, through their proven applications in ships, the durability to eclipse automotive engines.…”

Analysis of the Boost System for a High Performance 2-Stroke Boosted Uniflow Scavenged Direct Injection Gasoline (BUSDIG) Engine

“…In light of the advantages of the 2-stroke operation, a novel 2-stroke Boosted Uniflow Scavenged Direct Injection Gasoline (BUSDIG) engine has been designed and extensively researched at Brunel since 2015 [7]. Key designs of the proposed BUSDIG engine, including engine bore/stroke ratio [8], scavenge ports [9][10][11], opening profiles of scavenge ports and exhaust valves [12], intake plenum [13], injection strategies [14,15] and piston shape [16] have been systematically studied to optimise the scavenging performance and charge preparation of the BUSDIG engine.…”