A High-Efficiency Two-Stroke Engine Concept: The Boosted Uniflow Scavenged Direct-Injection Gasoline (BUSDIG) Engine with Air Hybrid Operation

Wang, Xinyan; Zhao, Hua

doi:10.1016/j.eng.2019.03.008

Cited by 18 publications

(20 citation statements)

References 62 publications

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“…The fuel economy is improved by the amount of fuel, and the throttle could be fully opened to reduce the engine pumping losses. In two-stroke engines, the fuel short-circuit loss can be eliminated by delaying the injection phase until the exhaust port is closed [40]- [41]. The delay of the injection phase indicates that the pressure in the cylinder gradually rises, which affects the fuel injection and spray characteristics.…”

Section: B the Effect Of The Ambient Pressure On The Opening Delay Amentioning

confidence: 99%

Drive Control Experimental Studies on the Injection Characteristics of a Self-Pressurized Injector

Wei

Liu

et al. 2021

IEEE Access

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As a miniaturized direct-injection (DI) solution, a self-pressurized injector is of great significance for small aviation piston engines, such as the spark-ignited two-stroke heavy-fuel engines. Accurate control of the timing and amount of injections is an important application prerequisite. In this paper, a high-speed camera is employed to study the spray characteristics, injection delay and fuel injection duration under three drive modes in a constant-volume bomb environment. The results show that the 8-A constantcurrent drive mode ensures the minimum injection dead zone and linearity of the flow characteristic curve, and the spray characteristics are close to those under a peak current of 10 A and holding current of the 8-A drive mode, which indicates that the drive circuit can be simplified. Ambient pressure increase leads to an increased injection delay and shortened injection duration. Therefore, it is recommended to apply the 10-A constant-current drive mode to reduce the impact of the ambient pressure. The double-injection characteristics of the self-pressurized injector are also studied, and the results demonstrate that when the interval time is reduced to 2 ms, the spray characteristics of the secondary injection are affected, and when the interval time is reduced to 0.2 ms, the spray characteristics of the primary injection are also affected. To ensure consistency of the spray characteristics, the minimum spray interval should be longer than 3 ms. INDEX TERMS aviation aircraft, direct injection, spray characteristics, piston engine, self-pressurized injector.

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Section: B the Effect Of The Ambient Pressure On The Opening Delay Amentioning

confidence: 99%

Drive Control Experimental Studies on the Injection Characteristics of a Self-Pressurized Injector

Wei

Liu

et al. 2021

IEEE Access

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“…The axis inclination angle (AIA) and swirl orientation angle (SOA) of scavenge ports are fixed at 90° and 20°, respectively, as suggested by a previous study. 37 The scavenge port height (SPH) and scavenge port opening (SPO) timing are 14 mm and 122 °CA, respectively. The exhaust valve duration (EVD) and exhaust valve opening (EVO) timing are fixed at 126 and 117 °CA, respectively.…”

Section: Specifications Of the Two-stroke Busdig Enginementioning

confidence: 99%

“…The current study aims to bridge this gap and performs a systematic analysis of the effect of piston shape design on the scavenging performance, in-cylinder flow formation and fuel/air mixing process with different fuel injection strategies in a two-stroke BUSDIG engine for automotive applications. 37…”

Section: Introductionmentioning

confidence: 99%

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

Wang

Zhao

2020

International Journal of Engine Research

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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.

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“…In this study, Reitz-Diwakar (R&D) 8 model, which is a popular breakup model and is frequently used in the engine simulations 38–40 is used in this study. In this model, droplet’s diameter changes continuously with time:…”

Section: Theory and Equationsmentioning

confidence: 99%

Effects of Turbulence on the secondary breakup of droplets in diesel fuel sprays

Khaleghi

Sani

Ahmadi

et al. 2020

Proceedings of the Institution of Mechanical Engineers, Part D:

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In this paper, the importance of turbulence effects on the procedure of droplet’s secondary breakup is studied. In the process of modeling the secondary breakup of a droplet, it is a common practice to presume that the droplet is moving in a laminar flow. However, it is evident that the critical Weber number is profoundly affected by the intensity of turbulence presented in the flow. As a result, the abovementioned supposition may lead to significant computational inaccuracy. This paper tends to perform a modification that considers the effects of turbulent flow on the secondary breakup of droplets. It is shown that the results obtained by the modified model are more precise and in a better agreement with experimental data. In this paper, spray behavior is predicted by a conventional breakup model and the one obtained by a modified model, which are both implemented in an in-house computer code. This CFD code accounts for engine simulation by solving the governing two-phase-flow equations using the Eulerian-Lagrangian approach in a three-dimensional coordinate system. To show the effects of turbulence, the changes in spray parameters such as droplet size distribution, spray tip penetration, and spray mean diameter, which is extracted from the two models are compared. Results have shown that the turbulence causes droplets to break in an earlier time, which leads to a higher rate of evaporation and lower penetration length. An interesting fact concluded in this paper is that the difference between the results of the two models decreases as the gas pressure is increased, which means the effects of turbulence become less important as the gas pressure increases.

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A High-Efficiency Two-Stroke Engine Concept: The Boosted Uniflow Scavenged Direct-Injection Gasoline (BUSDIG) Engine with Air Hybrid Operation

Cited by 18 publications

References 62 publications

Drive Control Experimental Studies on the Injection Characteristics of a Self-Pressurized Injector

Drive Control Experimental Studies on the Injection Characteristics of a Self-Pressurized Injector

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

Effects of Turbulence on the secondary breakup of droplets in diesel fuel sprays

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