Fuel spray vapour distribution correlations for a high pressure diesel fuel spray cases for different injector nozzle geometries (original) (raw)
Related papers
2017
The evolution of diesel fuel injection technology, to facilitate strong correlations of in-cylinder spray propagation with injection conditions and injector geometry, is crucial in facing emission challenges. More observations of spray propagation are, therefore, required to provide valuable information on how to ensure that all the injected fuel has maximum contact with the available air, to promote complete combustion and reduce emissions. In this study, high pressure diesel fuel sprays are injected into a constant-volume chamber at injection and ambient pressure values typical of current diesel engines. For these types of sprays the maximum fuel liquid phase penetration is different and reached sooner than the maximum fuel vapour phase penetration. Thus, the vapour fuel could reach the combustion chamber wall and could be convected and deflected by swirling air. In hot combustion chambers this impingement can be acceptable but this might be less so in larger combustion chambers w...
Characteristics of 3000 bar Diesel Spray Injection under Non-Vaporizing and Vaporizing Conditions
2012
Increasing fuel injection pressure has enabled continuous reduction of diesel emissions while sustaining the high thermal efficiency advantage of diesel engines. Current production diesel injectors operate in the range from 300 to 2000 bar. The ongoing trend for fuel injection systems is to higher injection pressures and smaller nozzle hole diameters for further emissions reduction and fuel efficiency improvements. Fundamental understanding of diesel spray characteristics including liquid penetration and cone angle is imperative to improve model development and facilitate the integration of elevated injection pressure systems into future diesel engines. Studies were conducted in an optically accessible constant volume combustion vessel under nonvaporizing and vaporizing conditions. A 7-hole injector, currently being developed for high injection pressure applications, was studied between 2000 and 3000 bar injection pressures with ultra-low sulfur diesel fuel. The study included two p...
Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering, 2010
Computational fluid dynamics results are presented providing information on the influence of multiple injection strategy on fuel vaporization characteristics under conditions typical of direct injection, turbocharged, high-speed automotive diesel engines. The fuel is assumed to be injected from a high-pressure common rail injector nozzle. Focus is given on the number of multiple injections and dwell-time on the evaporating spray plume development. Comparison between the different cases is performed in terms of liquid and vapour penetration curves, the spatial distribution of the air-fuel equivalence ratio and the fuel vapour spatial distribution difference between the cases considered. The results confirm that, under the operating conditions investigated, the liquid penetration length, known to freeze at a distance from the nozzle exit, is not significantly affected by the injection strategy, while vapour penetration follows the time-shift of the dwell-time. Longer dwell-times retard the diffusion of the vapour in the carrier gas. Although injection of small fuel quantities prior to the main pulse does not affect the liquid penetration, it contributes up to 5 per cent more stoichiometric fuel vapour present in the area of observed auto-ignition sites. Post injection and splitting of the main injection in two pulses modify the vapour distribution by creating two spatially separated fuel-rich zones.
Spray development and combustion characteristics for common rail diesel injection systems
2002
An attempt to understand, further, the processes of auto-ignition, combustion and ultimately emission formation for a common rail diesel injection system, has lead to an investigation into the effects in-cylinder density and fuel injection pressure have on liquid penetration, vapour formation and auto-ignition delay. Although several correlations for diesel spray penetration at different operating conditions have been presented in the literature, to date the findings are inconclusive with only limited investigation into the operating envelope expected in present and future high speed direct injection diesel engines.
The effect of in-cylinder thermodynamic conditions on the development of dense Diesel sprays injected from a high-pressure multi-hole injector under conditions typical of direct injection, turbocharged, high-speed automotive Diesel engines is evaluated using a recently validated computational fluid dynamics spray model. The required initial conditions have been estimated by a multi-phase nozzle hole cavitation model, and the spray characteristics are predicted using a dense-particle Eulerian-Lagrangian stochastic methodology, implemented in the in–house GFS (General Fluid Solver) code. Focus is given on the effect of injection of small fuel quantities prior to the main pulse on the evaporating spray development assuming initial air thermodynamic conditions at values corresponding to start of injection, end of injection and interpolating the values from in-cylinder temperature and pressure profiles. The results enlighten the crucial role of detailed information about the incylinder t...
The effect of dwell-time, fuel composition and nozzle hole shape on the development of dense Diesel sprays injected from high-pressure multi-hole common rail injector nozzles is evaluated using a validated computational fluid dynamics spray model. The initial conditions required as input to the model have been estimated by a multiphase nozzle hole cavitation model. The subsequent liquid plume development is predicted using an Eulerian-Lagrangian spray model, which accounts for liquid-core atomisation, droplet aerodynamic break-up, turbulent dispersion, droplet-to-droplet interaction and multi-component fuel vaporisation. The physical properties of the liquid fuel follow those of specified composition of pure hydrocarbons; the effect of different composition on the spray development during pilot and main injection periods is assessed. In the absence of experimental data to characterise the detailed spray structure under such operating conditions, the computational results presented in this work aim to provide some useful information about the effect of multi-injection strategy on fuel vaporisation characteristics under conditions typical of direct injection, turbocharged, high-speed Diesel engines.
Study of liquid and vapor phase behavior on Diesel sprays for heavy duty engine nozzles
Applied Thermal Engineering, 2016
A lot of effort has been put in the past years into the understanding of the delivery and development of diesel sprays in engine-like conditions as it has been proved to be a very important step for the design of better and cleaner commercial engines. Due to the bigger share of passenger cars engines over heavy duty engines, the research has been mainly focused on the investigation using small nozzles. This paper studies two nozzles with diameters representative of those that can be encountered in heavy duty engines, with the objective of corroborating the conclusions gathered for small nozzles representative of passenger car engines. The experimental data have been acquired by state-of-the-art techniques and equipment, and serves two purposes: further the understanding of the physics involved in the injection event and spray evaporation; and provide a dataset to CFD models that can accurately predict the behavior of the injection event. The tests were performed in a constant pressure flow vessel that allows to simulate enginelike conditions (1000 K and 15 Mpa) with continuous flow. The injection system tested is a novel, common-rail, solenoid-actuated injector for heavy duty applications which operates up to 220 Mpa. All experiments were performed in non-reacting conditions. The extended test matrix allowed to determine the influence of several parameters such as rail pressure, gas temperature, gas density, and nozzle geometry on the air-fuel mixing and evaporation process, by analyzing the spray penetration and spreading angle. Mie scattering and double-pass Schlieren optical configurations have been used to measure global liquid and vapor penetration, respectively. The data proves that spray penetration at low temperature can be up to 15% faster than spray penetration at high temperature conditions at the same density for the nozzles experimented, which limits the usability of low temperature experiments to infer the behavior of the injector at high temperature conditions. The data also shows that the nozzle with the biggest diameter provided the highest value of stabilized liquid length as expected. Also, when vapor phase is reached, the temperature has negligible effect on the global diesel spray morphology, and no influence on the tip penetration or on the spreading angle.
Non-Reacting Spray Characteristics of Gasoline and Diesel With a Heavy-Duty Single-Hole Injector
Frontiers in Mechanical Engineering
Gasoline compression ignition (GCI) is a promising combustion technology that could help alleviate the projected demand for diesel in commercial transport while providing a pathway to achieve upcoming CO2 and criteria pollutant regulations for heavy-duty engines. However, relatively high (i.e., diesel-like) injection pressures are needed to enable GCI across the entire load range while maintaining soot emissions benefits and managing heat release rates. There have only been a limited number of previous studies investigating the spray characteristics of light distillates with high-pressure direct-injection hardware under charge gas conditions relevant to heavy-duty applications. The current work aims to address this issue while providing experimental data needed for calibrating spray models used in simulation-led design activities. The non-reacting spray characteristics of two gasoline-like fuels relevant to GCI were studied and compared to ultra-low-sulfur diesel (ULSD). These fuels...
SAE Technical Paper Series, 2011
I would like to express my greatest gratitude to my supervisor, Prof. Keiya Nishida, who grants me the opportunity to study in his laboratory and provides me with kind guidance and tutorship not only in the scientific research but also in the everyday life. It is impossible for me to achieve this accomplishment within the three years without his patient and thoughtful instruction. I also would like to thank the associate Prof. Yoichi Ogata in our laboratory, his kind instruction especially his experience in numerical simulation facilitates our research. I express my special compliment to China Scholarship Council (CSC), a non-profit institution affiliated with the Ministry of Education of China, who sponsors me the living expense in Japan. The China General Consulate in Osaka gives us the immediate response and suggestion as soon as we have need.
Frontiers in Mechanical Engineering, 2022
Characteristics of diesel sprays injected through Cummins medium-duty ISB injectors were studied experimentally in an optically accessible constantvolume combustion vessel. The experiments were performed with ultralow-sulfur diesel (ULSD) under non-reacting and non-vaporizing conditions, including different ambient gas densities (23-65 kg/m 3), injection pressures (500-1,500 bar), and injection duration times (0.5-1.5 ms). The ambient temperature of the vessel was maintained at a room temperature of 313 K for all the tests. A systematic comparison was made between single-hole (SH) and multi-hole (MH) injector configurations. A plume-to-plume variation in spray penetration length was observed for various operating conditions. A substantial deviation was observed for a specific hole against the averaged plume, indicating that arbitrary selection of the plume index may result in inaccurate spray characterization of the MH injector. The penetration length of the MH injector was shorter than that of the SH injector under the same operating conditions, indicating that a spray model calibrated on SH injector data may not accurately predict the transient spray behavior of the MH injector in practical engine simulations. A square-root correlation of the spray penetration length was applied for both the SH and MH injectors. The spray penetration length and dispersion angles of the ISB SH injector were also compared with those of the heavy-duty Cummins ISX SH injector. While the ISX SH injector showed a faster penetration than the ISB SH injector, the dispersion angle was similar. The differences in spray penetration between ISB and ISX injectors followed the expected trend based on their nozzle hole diameters.