Near-nozzle spray and spray collapse characteristics of spark-ignition direct-injection fuel injectors under sub-cooled and superheated conditions

Wu, Shengqi; Xu, Min; Hung, David L.S.; Li, Tianyun

doi:10.1016/j.fuel.2016.06.080

Cited by 91 publications

(23 citation statements)

References 29 publications

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“…They account for this using a three-hole injector that shows interaction far later than a corresponding six-hole design. Similar approaches are taken by Leick et al 14 and Weber and Leick, 15 who use two-hole injectors to investigate the influence on individual jets, and Wu et al, 16 who compare a single-hole jet with a two-hole and with a six-hole injector. All authors agree that the most prominent feature of a single-jet spray under flash-boiling conditions is the significant increase in spray width close to the nozzle; however, atomization behaviour and air entrainment for the separated jet are not investigated in these publications.…”

Section: Flash Boiling In Gasoline Direct Injection Enginesmentioning

confidence: 91%

The influence of superheated injection on liquid and gaseous flow field of an experimental single-hole gasoline direct injection injector

Bornschlegel

Conrad

Durst

et al. 2019

International Journal of Engine Research

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In modern gasoline direct injection engines, the fuel is (partially) superheated for a significant proportion of the time during operation. This means that the vapour pressure of the fuel, or at least of many of its components, is higher than the ambient pressure inside the engine during injection. If the excess fuel enthalpy cannot be removed by evaporation at the free surface of the spray, the liquid phase boiling creates new surfaces. This phenomenon is known as flash boiling. Flash-boiling atomization produces smaller droplets and can therefore be beneficial as an additional atomization mechanism. Furthermore, it can reduce the penetration depth of a spray, although it also decreases the stability of fuel sprays. This is manifested in undesired targeting changes, that is, spray contraction due to jet-to-jet interaction. In extreme cases, a complete spray collapse can occur, where a multi-hole or hollow-cone spray contracts towards the spray axis and forms a jet-like structure that increases penetration depth. To understand the relationship between flash-boiling atomization and targeting changes, flash boiling was investigated with a single-hole generic injector without jet-to-jet interaction. In addition to macroscopic spray parameters, this study also focused on the flow field of the spray itself measured using laser Doppler anemometry, as well as the spray-induced flow field of the surrounding gas phase measured using fluorescent particle image velocimetry. The results show a strong radial expansion of the jet directly after nozzle exit, caused by internal flash boiling. It is shown that this expansion is caused by a zone of expanding fuel vapour in the centre of the spray. As a result, the displacement of air after injector opening as well as at the front of the spray is significantly increased, causing a decrease in spray front velocity and penetration depth. The stationary air entrainment, however, is only moderately increased as is the total amount of captured air, since the fuel vapour displaces air in the spray.

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Section: Flash Boiling In Gasoline Direct Injection Enginesmentioning

confidence: 91%

The influence of superheated injection on liquid and gaseous flow field of an experimental single-hole gasoline direct injection injector

Bornschlegel

Conrad

Durst

et al. 2019

International Journal of Engine Research

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“…The mechanism of the collapse could be explained by the theory in Ref. [33]. The fierce interaction between the plumes limit the transfer of the ambient gas from the outside to the closed central region, leading to pressure drop as the spray develops, and the pressure differential between the central region and ambient gas results in the collapse of the plumes.…”

Section: Experiments Apparatus and Conditions 21 Experimental Set-upmentioning

confidence: 99%

Characteristics of trans-critical propane spray discharged from multi-hole GDI injector

Zhang

et al. 2018

Experimental Thermal and Fluid Science

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“…However, because of mixture scavenging, which leads to fuel short-circuiting and excessive exhaust emissions, 1 people are trying to replace the conventional fuel injection system with gasoline direct injection (GDI) to reduce fuel consumption and CO 2 emission and to improve engine power output. 2 The GDI fuel injection system sprays fuel directly into the combustion chamber with a high injection pressure, resulting in a good atomization and evaporation process, 3,4 which have been widely used in automobiles. However, the normal GDI system has a complex structure which is not good for an aviation piston engine.…”

Section: Introductionmentioning

confidence: 99%

Optimization and simulation of a voice coil motor for fuel injectors of two-stroke aviation piston engine

Gao

Zhang

Wang

et al. 2019

Advances in Mechanical Engineering

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Two-stroke engines taking advantages of high power density and light weight as well as small size are widely used on aircrafts. Compared with conventional fuel injection system, gasoline direct injection technology can control the air-fuel ratio according to different working conditions and thus a more efficient combustion can be achieved. Normally, a solenoid valve is employed in the gasoline fuel injectors to control the injected fuel amount and timing. In this study, the performance of a novel voice coil motor for gasoline direct injection injectors of a two-stroke aviation engine is studied. The voice coil motor works as a linear actuator to pressurize the fuel, and thus the amount of injected fuel and the injection timing can be controlled by the driving current of the coil. As a result, the high-pressure pump of the conventional fuel injection system can be canceled. The working principle of the voice coil motor is described at first. Then, a finite element model of the voice coil motor is setup, and the influences of structure parameters including the coil turns, the magnetizer height, and the yoke thickness are analyzed. Subsequently, the magnetic equivalent circuit methodology is used to study the response characteristics of the voice coil motor. The results show that the coil turns, the magnetizer height, and the yoke thickness are three important parameters that will influence the electromagnetic force. The total mass and resistance of the coil and the coefficients k and k e are four important parameters that will influence the dynamic response time. A theoretical optimization of these parameters can improve the system performance of the voice coil motor significantly. The results of this study can provide a reference for the design of gasoline direct injection system for aviation piston engines.

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Near-nozzle spray and spray collapse characteristics of spark-ignition direct-injection fuel injectors under sub-cooled and superheated conditions

Cited by 91 publications

References 29 publications

The influence of superheated injection on liquid and gaseous flow field of an experimental single-hole gasoline direct injection injector

The influence of superheated injection on liquid and gaseous flow field of an experimental single-hole gasoline direct injection injector

Characteristics of trans-critical propane spray discharged from multi-hole GDI injector

Optimization and simulation of a voice coil motor for fuel injectors of two-stroke aviation piston engine

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