Gasoline Direct Injection Injector Research Articles

Improving high efficiency reactivity controlled compression ignition combustion with diesel and gasoline direct injection

Computational studies of heavy-duty diesel engine reactivity controlled compression ignition combustion employing both high pressure common rail diesel and low pressure gasoline direct injection were conducted to examine the benefits of using gasoline direct injection compared to port injected gasoline in improving engine performance. In the current study, multi-dimensional modeling using a discrete multi-component fuel vaporization version of the KIVA-3V code was used to examine gasoline direct injection strategies to improve CO and unburned hydrocarbon emissions while maintaining low indicated specific fuel consumption. For a 9 bar indicated mean effective pressure, 1300 r/min operating condition the engine-out CO and unburned hydrocarbonons were reduced by 27.1% and 7.1%, respectively, while engine-out NOx and soot emissions were maintained low. The predicted indicated specific fuel consumption was 159 g/kW h and the maximum pressure rise rate was 6.1 bar/°, which are comparable to or lower than those of the port injected reactivity controlled compression ignition combustion case. Although further study is needed to find optimum injection strategies to improve the combustion efficiency of reactivity controlled compression ignition combustion using gasoline direct injection, the current results show that direct-injecting both high and low reactivity fuels has the potential to reduce CO and unburned hydrocarbon emissions without sacrificing the thermal efficiency benefit of reactivity controlled compression ignition. Moreover, the reduced maximum pressure and pressure rise rate indicates the possibility of improved brake efficiency in reactivity controlled compression ignition combustion and lowered exhaust gas recirculation requirements. The study also explored the use of a low pressure gasoline direct injection injector for the diesel fuel and found that similar results were obtained to those with the high pressure common rail injector. This indicates that reactivity controlled compression ignition combustion is controlled by the global equivalence ratio and fuel reactivity stratification rather than by the location of the stratification in the combustion chamber. This indicates that the complexity and cost of the injection system can be reduced considerably.

Design of Driving Circuit of GDI Injector and Experiment Verification

In order to precisely control the injection responsivity of the Gasoline Direct Injection（GDI）engine，a higher requirement of the injector drive circuit should be achieved[5]. This paper introduces a new design of driving circuit for the injector of the EA888 engine. the thesis creates a simulation model of BOOST converter circuit using multisim simulation tool, Simulation results show that voltage ripple is less than 10%.The characteristics of GDI injector are measured and analyzed , the feasibility of the driving circuit is verified.

CFD optimization for GDI spray model tuning and enhancement of engine performance

► Two examples of CFD based optimization in the design of a GDI SI engine are given. ► The Simplex algorithm is used to automatically validate a GDI spray model. ► Portability of the model to three different GDI multi-hole injectors is proven. ► Optimization of the mixture formation to minimize a GDI engine consumption is also realized. ► Optimal double injection reduces fuel consumption more than single injections. Coupling a 3D Computational Fluid Dynamics (CFD) tool with a rigorous method of decision making is becoming indispensable in the design process of complex systems, as internal combustion engines. CFD based optimization (CFD-O) is here carried out on a single cylinder, four-valve, four-stroke gasoline direct injection (GDI) engine, to enhance mixture formation under stratified charge operation, hence to choose between the single or double injection strategy maximizing the engine power output. A 3D engine model is coupled with the Simplex algorithm to find the optimal synchronization of both injection and spark timing within the working cycle. CFD-O is also addressed to perform the validation of the gasoline spray model, that otherwise reveals tedious and time-consuming. The Simplex algorithm is used to tune the constants entering a model developed by authors, as applied to three different high pressure GDI injectors, preliminary experimentally characterized. Fully automatic procedures are assessed to be exploited in the phase of engine design, whose contribution may be of great importance to reduce development costs and time-to-market of new technologies.

분사 조건이 다공형 GDI 인젝터의 분무 거동에 미치는 영향

The purpose of this study is to investigate the overall spray behavior characteristics for various injection conditions in a gasoline direct injection(GDI) injector with multi-hole. The spray characteristics, such as the spray penetration, the spray angle, and the injection quantity, were studied through the change of the injection pressure, the ambient pressure, and the energizing duration in a high-pressure chamber with a constant volume. The n-heptane with 99.5% purity was used as the test fuel. In a constant volume chamber, the injected spray was visualized by the spray visualization system, which consisted of the high-speed camera, the metal-halide lamp, the injector control device, and the image analysis system with the image processing program. It was revealed that the injection quantity was mainly affected by the difference between the injection pressure and the ambient pressure. For low injection pressure conditions, the injection quantity was decreased by the increase of the ambient pressure, while it nearly maintained regardless of the ambient pressure at high injection pressure. According to the increase of the ambient pressure in the constant volume chamber, the spray development became slow, consequently, the spray tip penetration decreased, and the spray area increased. In additions, the circular cone area decreased, and the vortex area increased.

Fuel spray dynamic characteristics of GDI high pressure injection system

In order to improve the fuel consumption and exhaust emission for gasoline engines, gasoline direct injection (GDI) system is spotlighted to solve these requirements. Thus, many researchers focus on the investigation of spray characteristics and the fuel formation of GDI injector. This paper presents a complete numerical and experimental characterization of transient gasoline spray from a high pressure injection system equipped with a modern single-hole electric controlled injector in a pressurized constant volume vessel. The numerical analysis is carried out in a one-dimensional model of fuel injection system which is developed in the AVL HYDSIM environment. The experimental analyses are implemented through a self-developed injection rate measurement device and spray evolution visualization system. The experimental results of injection rate and spray dynamics are taken to tune and validate the built model. The visualization system synchronize a high speed CMOS camera to obtain the spray structure, moreover, the captured images are taken to validate the injector needle lift process which is simulated in the model. The reliability of the built model is demonstrated by comparing the numerical results with the experimental data. The formed vortex structure at 0.8 ms is effectively disintegrated at 6.2 ms and the spray dynamics become rather chaotic. The fuel flow characteristics within injector nozzle extremely influence the subsequent spray evolution, and therefore this point should be reconsidered when building hybrid breakup GDI spray model. The spray tip speed reach the maximum at 1.18 ms regardless of the operation conditions and this is only determined by the injector itself. Furthermore, an empirical equation for the spray tip penetration is obtained and good agreement with the measured results is reached at a certain extent. This paper provides a methodology for the investigation of spray behavior and fuel distribution of GDI engine design.

A study of spray development and combustion propagation processes of spark-ignited direct injection (SIDI) compressed natural gas (CNG)

Compressed natural gas (CNG) is regarded as one of the most promising alternative fuels, and may be the cleanest fuel for the spark-ignited (SI) engine. Its high octane number permits a high compression ratio, thereby leading to higher thermal efficiency, and lower emissions could be realized by using CNG. In the SI engine, direct injection (DI) technology significantly increases the engine volumetric efficiency and decreases the need of throttle valve for control purposes. During low load and speed conditions, DI allows engine operation under ultra-lean conditions by realizing the stratified charge. This enables the use of extremely lean air–fuel mixtures, thereby reducing fuel consumption.For the design and optimization of an SI engine adopting DI technology with CNG fuel, it is necessary to investigate the spray development process, the ignition probability, and the combustion propagation process of DI CNG. In this study, a combustion chamber with a visualization system is designed and built. CNG is injected into the combustion chamber by a gasoline direct injection (GDI) injector and ignited by a spark plug placed near the injector. The close arrangement of the injector and spark plug provides a stratified charge of CNG around the spark discharge position. Images of the CNG spray development and combustion propagation processes were digitally recorded and analyzed. The results of this study can contribute important data for the design and optimization of spark-ignited direct injection (SIDI) CNG engines.

Spray Characteristics Study of DMF Using Phase Doppler Particle Analyzer

2,5-dimethylfuran (DMF) is currently regarded as a potential alternative fuel to gasoline due to the development of new production technology. In this paper, the spray characteristics of DMF and its blends with gasoline were studied from a high pressure direct injection gasoline injector using the shadowgraph and Phase Doppler Particle Analyzer (PDPA) techniques, This includes the spray penetration, droplet velocity and size distribution of the various mixtures. In parallel commercial gasoline and ethanol were measured in order to compare the characteristics of DMF. A total of 52 points were measured along the spray so that the experimental results could be used for subsequent numerical modeling. In summary, the experimental results showed that DMF and its blends have similar spray properties to gasoline, compared to ethanol. The droplet size of DMF is generally smaller than ethanol and decreases faster with the increase of injection pressure. The mean velocity of DMF spray droplets is similar to gasoline and higher than ethanol. Ultimately, the spray characteristics of DMF are better suited to the gasoline engine technology than its counterpart, ethanol. © 2010 SAE International.

Atomization and spray characteristics of bioethanol and bioethanol blended gasoline fuel injected through a direct injection gasoline injector

The focus of this study was to investigate the spray characteristics and atomization performance of gasoline fuel (G100), bioethanol fuel (E100), and bioethanol blended gasoline fuel (E85) in a direct injection gasoline injector in a gasoline engine. The overall spray and atomization characteristics such as an axial spray tip penetration, spray width, and overall SMD were measured experimentally and predicted by using KIVA-3V code. The development process and the appearance timing of the vortices in the test fuels were very similar. In addition, the numerical results accurately described the experimentally observed spray development pattern and shape, the beginning position of the vortex, and the spray breakup on the spray surface. Moreover, the increased injection pressure induced the occurrence of a clear circular shape in the downstream spray and a uniform mixture between the injected spray droplets and ambient air. The axial spray tip penetrations of the test fuels were similar, while the spray width and spray cone angle of E100 were slightly larger than the other fuels. In terms of atomization performance, the E100 fuel among the tested fuels had the largest droplet size because E100 has a high kinematic viscosity and surface tension.

Synopsis of experimentally determined effects of electrostatic charge on gasoline sprays

The effects of applying electrostatic charge to gasoline fuel sprays from a gasoline direct injection (GDI) injector have been investigated. The injector was modified by the addition of an electrically isolated electrode installed on its tip. The morphology of electrostatically charged and non-charged sprays was characterized using a Mie scattering visualization technique, Fraunhofer diffraction measurements of droplet size, and particle imaging velocimetry (PIV) measurements of the velocity field. The PIV measurements showed that the electrostatic charging of the sprays enhanced the vortical motion of the droplets and produced empty pockets within the spray. Furthermore, the charged sprays penetrated further and were wider than the non-charged sprays. The results of the PIV measurements were complemented by Fraunhofer diffraction (Malvern) measurements, which showed significantly increased consistency of droplet size for the electrostatically charged case. The extent of charging of the fuel sprays was determined with combined measurements of the mass and the charge carried by the sprays. In parallel, the electric field generated by the presence of the charged electrode was computed by numerically solving the Laplace equation at the vicinity of the injector tip. With this data, the relative magnitudes of the electrostatic and inertial forces were compared.

Experimental investigation of the possibility of automotive gasoline spray manipulation through electrostatic fields

An experimental evaluation of the possibility of using 'electrospray' in automotive technology. To this extent, a commercially available Gasoline Direct Injection (GDI) injector was modified in order to induce electrostatic charge in the non-conducting fuel spray. Spray morphology was characterised with visualisation experiments and spray structure was probed with Particle Image Velocimetry (PIV) and Fraunhofer light diffraction droplet size measurements. PIV data showed that electrostatically charged sprays presented pockets that were sparsely populated by droplets and areas of increased vortical motion at an injection pressure where the non-charged sprays were much more coherent. In this sense, electrostatic charging at relatively low pressures aided in the generation of flow patterns that are exhibited at higher pressures for non-charged sprays. Measurements of droplet diameter using a Fraunhofer light diffraction technique provided indications of increased resistance to droplet coalescence and a much smaller cyclic variation of droplet size for the electrostatically charged sprays.

Numerical and experimental study of the vaporization cooling in gasoline direct injection sprays

The spray of a high-pressure gasoline direct injection (GDI) injector has been studied experimentally at engine-like conditions and by numerical simulations. The high-pressure injection of isooctane fuel into a chamber leads to an evaporation of the injected liquid and to the formation of an ignitable fuel–air mixture at particular locations in the spray. The energy needed for this evaporation is provided by the background gas which in turn experiences a temperature drop. Experiments were conducted using the pure rotational coherent anti-Stokes Raman scattering (RCARS) technique in order to measure the temperature of the gas phase. The numerical simulation were done with a mixed Eulerian–Lagrangian approach. For varying injection pressures, a clear influence on the vaporization cooling has been found in the numerical results which is in contrast to the experiments. However, the experimental results for varying fuel temperatures are well reproduced.

Atomization characteristics and prediction accuracy of LISA-DDB model for gasoline direct injection spray

In this paper, the spray atomization characteristics of a gasoline direct-injection injector were investigated experimentally and numerically. To visualize the developing spray process, a laser sheet method with a Nd :YAG laser was utilized. The microscopic atomization characteristics such as the droplet size and velocity distribution were also obtained by using a phase Doppler particle analyzer system at the 5 MPa of injection pressure. With the experiments, the calculations of spray atomization were conducted by using the KIVA code with the LISA-DDB breakup model. Based on the agreement with the experimental results, the prediction accuracy of LISA-DDB breakup model was investigated in terms of the spray shapes, spray tip penetration, SMD distribution, and axial mean velocity. The results of this study provides the macroscopic and microscopic characteristics of the spray atomization, and prediction accuracy of the LISA-DDB model.

Gas-phase temperature measurement in the vaporizing spray of a gasoline direct-injection injector by use of pure rotational coherent anti-Stokes Raman scattering

Pure rotational coherent anti-Stokes Raman spectroscopy is applied for quantitative gas-phase temperature measurements in the vaporizing spray of an automotive fuel injector. Interferences from elastically scattered stray light are greatly reduced by use of a polarization technique and spectral filtering in a double monochromator. The applicability of this technique to probing low-temperature sprays is successfully demonstrated.

An experimental study on the spray behavior and fuel distribution of GDI injectors using the entropy analysis and PIV method

To improve the fuel consumption and exhaust emission for gasoline engines, Gasoline Direct Injection (GDI) system was spotlighted to solve above requirements. Thus, many researchers have been studied to investigate the spray characteristics and the fuel formation of GDI injector. In this study, we tried to study the characteristics of a direct injection gasoline spray by using entropy analysis and PIV methods. The entropy analysis is based on the concept of statistical entropy, and it identifies the degree of homogeneity in the fuel concentration. The PIV method was adopted to determine the fluid dynamics information at the spray. Also fuel formation within the cylinder in the case of early injection timing greatly influences combustion characteristics. This study developed the analyzing system for the mixing fuel with air using the Mie scattering method to visualize the fuel distribution. This technique was applied to a visualization single cylinder engine in order to investigate the spray behavior and fuel distribution.

Application technique of particle image velocimetry and entropy analysis toinvestigate spray structure for gasoline direct injection injector

To improve the fuel consumption and exhaust emission for gasoline engines,the GDI (gasoline direct injection) system was spotlighted to meet theserequirements. Many researchers have performed studies to investigate the spraycharacteristics and the mixture formation of the GDI injector. In this work, westudied the spray characteristics of a gasoline direct injector by using entropyanalysis and particle image velocimetry (PIV) methods. The entropy analysis isbased on the concept of statistical entropy, and it identifies the degree ofhomogeneity in the fuel concentration. The PIV algorithm was developed toelucidate the correlation between entropy and vorticity. From the applied resultson a direct injection gasoline spray, we could find that the direct diffusionphenomenon was a dominant factor in the formation of a homogeneous mixturedownstream of the GDI spray, especially under vaporizing ambient conditions,and the mixing phenomenon was also progressed by momentum exchange withinduced air. In addition, these results revealed that entropy analysis and PIV arevery effective methods for the analysis of the mixing process, and the entropyvalues increase with the progress of uniformity in the diffusion process.

엔트로피 해석과 PIV를 이용한 직접 분사식 가솔린의 분무 특성에 관한 연구

To improve the fuel consumption and exhaust emission for gasoline engines, GDI(Gasoline Direct Injection) system was spotlighted to solve above requirements. Thus, many researchers have been studied to investigate the spray characteristics and the mixture formation of GDI injector. In this study, we tried to study the spray characteristics of a gasoline direct injector by using entropy analysis and PlV methods. The entropy analysis is based on the concept of statistical entropy, and it identifies the degree of homogeneity in the fuel concentration. The PlV method was adopted to determine the fluid dynamics information at the spray. From the applied results on a direct injection gasoline spray, we could find that the direct diffusion phenomena was a dominant factor in the formation of a homogeneous mixture at downstream of GDI spray especially under vaporizing ambient conditions, and mixing phenomena was also progressed by momentum exchange with induced air. In addition, the correlation between entropy and vorticity strength enabled to find their relation.

Measurement of droplet size distribution of gasolinedirect injection spray by droplet generator and planar imagetechnique

To understand the spray characteristics that are related tothe characteristics of emissions and the combustion of directinjection engines, the planar image technique was applied to measurethe distribution of droplet size. This technique was based on theprinciples of laser-induced fluorescence (LIF) and the Mie scatteringof droplets in the spray. We decided to apply the LIF and Miescattering intensity indices for unleaded gasoline to this techniquewith a droplet generator. The fluorescence and scattering signalswere imaged simultaneously by an optical system composed of adoubling prism, optical filters and an ICCD camera. Relative Sautermean diameter distributions according to space and time were obtainedby calculating the ratio between two light intensities, and thedistributions were quantified with a laser diffraction particleanalyser. Experimental results have shown that the characteristics ofthe gasoline direct injection injector varied with injectionpressure.

Fuel-Spray Characteristics of High Pressure Gasoline Injection in Flowing Fields.

The direct infection into the cylinders has been regarded as a way of the reduction in fuel consumption and pollutant emissions. The spray produced from the direct injector is of paramount importance in GDI (Gasoline Direct Injection) engines in that the primary atomization process must meet the requirement of quick and complete evaporation and combustion especially to prohibit the excessive HC emissions. The interaction between air flow and fuel spray was investigated in a steady flow system embodied in a wind tunnel to simulate the variety of flow inside the cylinder of the GDI engine. The direct Mie scattered and Shadowgraph images presented the macroscopic view of the liquid sprays and vapor fields. The velocity and particle size of fuel droplets were investigated by Phase Doppler Anemometer (PDA) system. The processes of atomization and evaporation with a GDI injector were observed and consequently utilized to construct the data-base for the spray and fuel-air mixing mechanism as a function of the flow characteristics.