Spray Tip Penetration Research Articles

Experimental characterization on injection and spray of coal-derived liquid fuel

Coal-derived liquid fuels (CDLs) are petroleum diesel's (PD) alternatives produced by coal liquefaction. The injection and non-evaporating spray characteristics of CDLs, including diesel from direct coal liquefaction (DDCL), diesel from indirect coal liquefaction (DICL), and their blends (DBCL), were discussed. The high-pressure common rail test bench was used to evaluate the injection delay, injection rate, injection quantity, single injection heat value, and injector inlet pressure. A constant volume chamber along with high-speed camera was used to visualize the spray, then measuring the spray tip penetration distance, spray cone angle, and spray area. Besides, injection tests were conducted using injectors removed from engines that had finished durability tests fueled with DBCL and PD. The results revealed that DDCL had shorter injection delays and more mass injection quantity than PD, with an injection heat value 7 % higher at a rail pressure of 140 MPa. Regarding the spray, PD had a longer spray tip penetration distance and smaller cone angle than CDLs. On test conditions, the spray Sauter mean diameters of DDCL and DICL were over 30 % less than that of PD. Inferring from the reduction in injection rate and quantity, PD generated more clog in the injector hole than DBCL.

Superheated fuel sprays: A comparative study of flash boiling ammonia fuel sprays with methanol, ethanol, and gasoline for multi-hole fuel injection

The rising energy demand creates a huge need to explore and implement sustainable alternative fuels e.g., ammonia, hydrogen, methanol, ethanol, etc. to mitigate emission challenges and significantly lower CO2 emissions. Ammonia has gained much attention as promising alternative fuels for internal combustion engines due to its carbon-neutral nature, which can reduce the carbon footprint in transportation. The advantages of ammonia as a fuel includes carbon-free nature, high volumetric energy density compared to hydrogen, and renewable resource-based production. However, there is lack of the deep understanding of the ammonia spray characteristics and fuel-air mixing process, in particular, the superheated spray, which potentially improve the vaporization and fuel-air mixing. This study focused on investigating the impact of superheating on ammonia, methanol, ethanol, and gasoline fuel sprays by heating the fuel injector tip from non-evaporating to flash boiling temperatures. The fundamental spray parameters were investigated in a constant volume spray chamber using a multihole solenoid driven injector for 150 bar constant injection pressure under 10 bar and 30 bar chamber pressure conditions. To observe flash boiling and the dual-phase flow, a Z-type Schlieren imaging technique, known for its sensitivity to density gradients, was used. The experimental results indicated that ammonia spray behavior significantly differed from other tested fuels for both under cold and superheated conditions. The effect of superheating on methanol, ethanol, and gasoline sprays was very similar, resulting in the shrinkage of spray width and the merging of adjacent plumes into a single thick cloud of spray for elevated tip temperatures. However, ammonia sprays exhibited considerable differences in evaporative conditions, developing a more significant dual phase flow than other fuels upon increment in tip temperature. Overall, the results showed that the spray tip penetration and area for all tested fuels reduced upon heating.

Optical study on spray mixing, flame propagation and jets evolution within visible methanol active pre-chamber for turbulent jet ignition

Methanol spray impingement, mixing, flame propagation and jet evolution within the narrow-confined active pre-chamber (APC) with complex walls were experimentally observed by optical method for the first time. The effects of injection pressure and duration was investigated on an actual-geometry optical APC assembled in constant volume combustion chamber (CVC). Exploration on APC internal processes within static environments forms the basis for optimization of APC and analysis of jet formation. Mie scattering coupled with flame natural luminosity imaging were used to record spray mixing and combustion. The results show that in the APC with narrow-confined space, methanol spray undergoes three wall impingements, inducing a tumble that promotes mixing. High injection pressure enhances rapid spray tip penetration, while long injection duration slows methanol diffusion. In longer injection duration cases, the spray tip after the third impingement interferes with subsequent sprays. For higher injection pressure, this interference occurs in the APC cone section due to a larger spray cone angle, whereas for lower pressure, it happens in the APC duct section. Higher injection pressure also causes more spray to impact the APC bottom after the first wall impingement, hindering flame acceleration in the duct section. Irregular flame propagation is observed in the APC cone section due to wider space and uneven mixture conditions, while the convergent geometry from the APC throat to the duct section significantly accelerates flame propagation. The APC jet appears due to the pressure difference between the APC and the main chamber, with the brightness and length of the visible flame jet increasing with APC flame luminosity and pressure difference. A Mach ring structure is observed initially, but the jet velocity decreases as the Mach ring disappears during the APC inner flame extinguishing process. Through this study, the actual spraying and combustion process in APC is experimentally captured and revealed, which are an important contribution for APC optimization and development.

Experimental Study on the Spray Characteristics of Diesel and Hydrotreated Vegetable Oil (HVO) Fuels under Different Injection Pressures

This investigation employed the diffused back-illumination (DBI) technique to analyze the spray characteristics of hydrotreated vegetable oil (HVO) fuel at three injection pressures and compared them with conventional diesel fuel. The results showed that as the injection pressure increased, the peak injection rates of both the HVO and diesel increased. At injection pressures above 120 MPa, the injection rates of both fuels were nearly identical, though differences were observed at lower pressures. Increasing the injection pressure reduced the injection delay. The HVO fuel exhibited a shorter spray tip penetration, lower equivalence ratio, larger spray angle, and spray volume, but its spray angle stability was lower than that of diesel. The ambient gas entrainment rate primarily occurred in two stages, significantly influenced by the spray breakup development stage. For diesel sprays, the injection pressure mainly affected the equivalence ratio near the nozzle with minimal downstream impact. Dent’s model provided better predictions of the penetration distance for diesel, while Hiroyasu’s model was more accurate in predicting the penetration distance of the HVO at 120 MPa and 180 MPa. Inagaki’s model performed better in predicting the spray angle for diesel, whereas Hiroyasu’s model was more accurate for the HVO spray angle predictions. Through this research, a better understanding of the spray characteristics of green fuels will be achieved, providing a reference for the design and optimization of new generation engines.

Advancing Fuel Spray Characterization: A Machine Learning Approach for Directly Injected Gasoline Fuel Sprays

Compression ignition engines when operated on gasoline fuels cause significant reduction in NOx and particulate emissions. In such advanced combustion strategy, the fuel-oxidiser mixing process, intensified by the prolonged ignition delays of gasoline fuels, directly affects the stability and efficiency of combustion. Thus, optimising fuel spray characteristics leads to optimisation of injector design, engine performance and subsequent decrease in emissions. Since spray development is a complex process that involves wide range of length and time scales, computationally expensive modelling techniques can be replaced with machine learning (ML) models. These ML models are employed to predict spray characteristics utilizing datasets generated from comprehensive spray studies. In this work, a dataset of about 5400 instances taken from non-evaporating gasoline fuel spray imaging experiments under Gasoline Compression Injection (GCI) engine conditions is used to train various ML models with data split of 70 % and 30 % for training and testing, respectively, with five-folds cross-validation performed within the training. The fuel injection pressure (60 – 150 MPa), chamber pressure (0.1 – 2 MPa), nozzle diameter, nozzle hole conicity and injection duration are used as input features to the models for predicting the spray tip penetration and spray angle. The performance of four ML models was evaluated and compared under default and tuned hyperparameters against experimental data and available physics-based correlations in the literature. The models include random forest, extreme gradient boosting, multilayer perceptron, and elastic-net. The results show that the hyperparameter-tuned extreme gradient boosting model performs best in predicting the spray parameters. The overall model performance was evaluated using the coefficient of determination (R2), mean absolute error (MAE), and root mean squared error (RMSE), resulting in values of 0.884, 0.651, and 1.571, respectively. This study presents compelling evidence demonstrating the effectiveness of ML as a powerful tool for isolating non-linear behaviors from physical processes. By effectively decoupling these behaviors, ML enhances the accuracy of predicting spray characteristics while significantly reducing computational costs. The application of ML in fuel injector design has the potential to revolutionize engine performance and contribute to substantial reductions in emissions.

Investigating Spray Characteristics of Synthetic Fuels: Comparative Analysis with Gasoline

Article Investigating Spray Characteristics of Synthetic Fuels: Comparative Analysis with Gasoline Weidi Huang 1,2, Mitsuharu Oguma 2, Koichi Kinoshita 2, * , Yohko Abe 2, and Kotaro Tanaka 1,3 1 Carbon Recycling Energy Research Centre, Ibaraki University, 4-12-1 Nakanarusawa, Hitachi 316-8511, Japan 2 Research Institute for Energy Conservation, National Institute of Advanced Industrial Science and Technology, Namiki 1-2-1, Tsukuba 305-8564, Japan 3 Graduate School of Science and Engineering, Ibaraki University, 4-12-1 Nakanarusawa, Hitachi 316-8511, Japan * Correspondence: koichi-kinoshita@aist.go.jp Received: 13 March 2024; Revised: 22 May 2024; Accepted: 31 May 2024; Published: 5 June 2024 Abstract: Studying synthetic fuels is imperative due to their potential to offer sustainable alternatives to conventional fossil fuels, thereby addressing environmental concerns, enhancing energy security, and facilitating the transition to cleaner and more efficient transportation systems. This study presents an experiment analysis concentrating on spray characteristics of five types of synthetic fuels (bio-naphtha, EtG, G40, bio-ethanol, and DMC) in a comparison with gasoline. The experiment was conducted ranging from non-evaporated conditions to evaporated conditions, to thoroughly assess the spray behavior of the tested fuels. Results showed that EtG and G40 share similar properties with conventional gasoline. The discharge coefficient (Cd) was found to increase closely linearly with the square root of fuel density. Under non-evaporated condition (Ta = 25 °C), except for DMC, the spray tip penetration of other fuels deviates within ±5% compared to gasoline. Under evaporated condition (Ta = 200 °C), EtG maintains a spray tip penetration within ±5% of gasoline, while bio-naphtha, G40, and DMC fall within ±10% of gasoline. Notably, bio-ethanol shows a 12% higher penetration compared to gasoline, likely due to its slower evaporation and higher latent heat of vaporization.

An Experimental Study on the Flash Boiling Characteristics of Liquid Ammonia Spray in a Constant Volume Chamber under High Injection Pressure

The spray characteristics of liquid ammonia under various ambient pressures and temperatures were analyzed in a constant volume chamber to cover a wide range of superheat degrees. The injection pressure was set as 70 and 80 MPa with ambient pressure ranging from 0.2 to 4 MPa. The ambient temperature was 500 K. The results showed that the higher the injection pressure, the greater the kinetic energy obtained. The droplet fragmentation was enhanced, and the phenomenon of gradual separation of the gas–liquid region occurred with increasing injection pressure. Under flash boiling spray conditions, the spray developed faster than non-flash boiling and transition flash boiling spray under the same injection pressure. In addition, the flash boiling spray tip penetration of the gas and liquid increased more than that of cold spray, and the fluctuation of the late stage of the injection was relatively large. Therefore, the injection pressure has a greater effect on the spray tip penetration of flash boiling spray. Moreover, ambient pressure greatly influences the flare flash boiling spray. The spray resistance phenomenon was found during the spray development in the flare flash boiling condition. With the increase in ambient pressure, the spray tip penetration of flash boiling spray decreases due to the reduction in the pressure difference inside and outside the spray hole and the restriction of ambient gas. Meanwhile, owing to the low ambient pressure and ambient density, the liquid penetration in the initial phase of the flare flash boiling spray will be abnormally shorter than that of the non-flash boiling spray.

Investigation into the Impact of Piston Bowl Size on Diesel Engine Characteristics with Changes in Fuel Injection Pressure and Boost Pressure

This study presents the effects of piston bowl size on the characteristics of a four-stroke single-cylinder diesel engine, which is considered in relation to changes in factors such as fuel injection pressure and turbocharger pressure. The study was carried out by 3D modeling using AVL Fire with an omega combustion chamber size and dimensions determined by the ratio between the diameter and depth of the piston bowl, which varies from 3.4 to 10.0. Additionally, the turbocharger pressure varies from 0.15 to 0.45 MPa at an engine speed of 1400 rpm and fuel injection pressure up to 300 MPa. The results show that the engine reaches the best values of indicated power, fuel efficiency, and a substantial decrease in emissions of nitrogen oxides at a turbocharger pressure from 0.25 to 0.35 MPa and with a ratio of the diameter to the depth from 7.8 to 10. However, the injection angle changes slightly, and the penetration depth and the tip velocity decrease with increasing boost pressure. While the piston bowl parameters only impact significantly on the tip velocity, the penetration and the spray angle are almost unchanged. In addition, the variation in the diameter of the combustion chamber has an influence on the fluctuation of the spray tip velocity and penetration.

An optical investigation on macro spray characteristics of convergent-divergent ducted fuel injection under high ambient pressures

The fuel-air mixing process can be improved via straight (ST) ducted fuel injection along with the risk of greater heat transfer loss due to prolonged spray tip penetration (STP) and spray impingement. We proposed the convergent-divergent (CD) duct spray in this study to produce acceptable STP and wider spray cone angle (SCA) for improving engine efficiency. STP and SCA are closely related to ambient pressure. This paper aims to explore the influence of ambient pressure on the macro spray characteristics of CD duct spray for better fuel-air mixing with the analysis of spray air entrainment (SAE). The Schlieren system was used to record the spray morphology of different duct sprays under ambient pressures of 20, 30, 40, and 50 bar. The results showed that compared with free spray, with the increase of ambient pressure, the application of CD duct can more effectively improve the SCA increase rate of free spray. With the ambient pressure changes from 20 to 50 bar, the SCA increase rate is up to 20.17% for free spray, and the SCA increase rate increased more than three times to 76.96% with ST3 duct and more than eight times to 173.06% with CD 4.5 duct compared with free spray respectively. The SAE of CD3 and ST3 duct sprays is higher than that of other sprays. CD4.5 and CD6 duct sprays reduce the probability of spray-wall impingement but along with a certain reduced amount of SAE.

Nozzle effects on spray combustion and emissions in compression ignition engines using waste cooking oil biodiesel: A computational fluid dynamics analysis at varying injection pressures

AbstractThis study investigates the spray combustion characteristics of waste cooking oil (WCO) in comparison between a swirl nozzle (SN) and a conventional nozzle (CN) of equal cross‐section. n‐Heptane, methyl decanoate, and methyl‐9‐decenoate were used as WCO substitutes in the simulation. The research primarily focuses on multiphase flow using the Lagrangian‐drop Eulerian‐fluid (LDEF) method, employing an equilibrium phase spray model (EP) for droplet behaviour analysis. The model's efficacy was validated through comparisons with experimental works by other engine researchers. At varying injection pressures, the study found that SN slightly reduced evaporative spray tip penetration but increased the cone angle compared to CN. This suggests early fuel jet disintegration and improved air entrainment due to SN. SN also showed a higher heat release rate and temperature, with soot reduction between 3.20 to 6.72% as injection pressure increased from 100 to 300 MPa. This indicates that SN achieves better air‐fuel mixture than CN. Further, the study discovered that the influence of SN becomes more significant as the rheological properties of WCO lessen under ultra‐high injection pressures.

Numerical simulation and spray model development of liquid ammonia injection under diesel-engine conditions

Ammonia is regarded as a promising alternative fuel in internal combustion engine for its potential to reduce carbon emissions. Injection process of liquid ammonia will affect air-fuel mixture distribution and therefore combustion efficiency and NOx emissions. However, the experimental studies of liquid ammonia injection under engine conditions are limited, and the key impact factors of spray evolution are still unclear. This study aims to evaluate the applicability of numerical models for liquid ammonia spray, and numerically investigate spray characteristics under diesel-engine conditions (ambient temperature > 800K, ambient pressure > 2 MPa). Large eddy simulation coupled with Lagrangian particle tracking method were conducted, and the results show that the non equilibrium - Frössling phase change model coupled with Schiller-Naumann drag model can provide a good prediction of spray penetration. Liquid penetration increases with ambient pressure decreasing; vapor penetration increases with ambient density decreasing, but insensitive to ambient temperature. Temperature - mixture fraction distribution is sensitive to ambient temperature and superheat degree. Besides, a three-stage 0D model of spray tip penetration under diesel-engine conditions is developed firstly, which can reflect the key impact factors of ammonia spray evolution and provide theoretical support to optimize fuel injection strategy of liquid ammonia-fueled engines.

An experimental study the cross spray and combustion characteristics diesel and ammonia in a constant volume combustion chamber

Recently, the use of ammonia, a carbon-free fuel, in internal combustion engines, particularly in dual fuel dual direct injection engines, has attracted wide attention. However, the spray and combustion characteristics of diesel and ammonia dual direct injection especially on cross injections remain unclear. An optical study of diesel and ammonia spray and combustion was conducted using a constant-volume combustion chamber. The results revealed that spray tip penetration (STP) and spray projected area (SPA) of ammonia are lower than those of diesel, indicating that ammonia has a higher evaporation rate and a smaller diffusion rate than diesel. Besides, diesel and ammonia atomization was promoted through cross injection and collisions. As the cross injection interval increased, the liquid-phase STP of the collision spray increased, and its liquid-phase SPA decreased, while its vapor-phase SPA increased, promoting the diffusion and evaporation rates of the collision spray. In addition, increasing the interval of diesel and ammonia injection can shorten the ignition delay, and increase the flame lift-off length, leading to a more intense combustion process and less soot emissions. Therefore, the combustion and emission characteristics can be effectively improved by adjusting the injection timing of the two fuels reasonably.

Study of RP-3/n-butanol fuel spray characteristics and ANN prediction of spray tip penetration

The blending of aviation fuel with biomass is currently an effective way to meet the demand for sustainable aviation fuel. This study tested the physical parameters of fuel blends of 0∼30 % volume fraction n-butanol with RP-3 aviation kerosene, and the macroscopic characteristics of the spray penetration tip (STP), spray cone angle (SCA), and spray area (SA) of the blends were investigated by computational fluid dynamics at different injection pressures (100–160 MPa) and ambient pressures (0.8–1.5 MPa). A model using artificial neural networks (ANN) was built to forecast the STP of the fuel. The findings indicate that the blending of n-butanol has little impact on the spray characteristics of the fuel. The STP and SA of the blended fuel rise but have a small effect on the SCA as injection pressure increases. The STP and SA of the fuel gradually decrease, while the SCA becomes larger as ambient pressure increases. NET9 which has 6 input layers, 9 hidden layers and 1 output layer with the best performance (RMSE: 0.46213, R2: 0.99969) was selected and the prediction error of NET9 was less than 3 %. This indicates that the model has the best prediction ability and can be used in subsequent research.

Experimental investigation on a novel external-mixing prefilming atomizer for advanced aircraft engines

As a crucial component of aircraft engine combustors, the external-mixing prefilming atomizer exhibits significant advantages in enhancing combustion efficiency and reducing pollutant emissions. However, the intricate relationship between spray characteristics, droplet breakup mechanisms, flow fields, and geometric parameters of the external-mixing prefilming atomizer remains poorly understood. This paper presents a novel external-mixing prefilming atomizer, aiming to address this knowledge gap. Additionally, particle image velocimetry (PIV), high-speed Schlieren photography, and particle image analysis (PIA) measuring systems were employed to gain insights into the spray characteristics and droplet breakup mechanism of the external-mixing prefilming atomizer under various swirl flow fields. The obtained results reveal the formation of two distinct regions, namely a low-density area and a high-density area. Notably, the number of droplets in the low-density area, located within 0–2 cm from the central axis, is significantly lower compared to the high-density area situated further away from the central axis. The breakup of droplets in the low-density region is primarily attributed to the inner swirl airflow, while the outer swirl airflow induces droplet breakup in the high-density region. As the Reynolds number of the incoming flow increases, the air-liquid ratio (ALR) and Weber number also increase, thereby enhancing the fuel breakup effect. The Schlieren results reveal a two-stage spray development process. The initial stage is characterized by the dominant momentum of the dense spray, with the spray tip penetration (STP) exhibiting a relatively slow increase. The aerodynamic force of airflow plays a crucial role in governing the breakup and transport of droplets, leading to a linear variation of STP over time. As the swirl number increases, there is an enhanced momentum exchange between droplets and airflow, resulting in accelerated spray penetration and droplet breakup.

A comparative analysis of internal flow and spray characteristics in triangular orifices with diesel and biodiesel

This paper presents an inquiry into the internal flow and spray behavior of diesel and biodiesel in a triangular orifice, using experimental and numerical methods. The inner flow was analyzed through the implementation of Large Eddy Simulation model. Furthermore, two high-speed cameras were utilized to capture spray images of the major and minor axes of the triangle-shaped nozzle simultaneously. The investigation revealed that, in comparison to diesel, biodiesel exhibited a higher discharge coefficient. Additionally, the vorticity magnitudes and turbulence vortex structures for biodiesel were consistently lower than those for diesel. The use of biodiesel can hinder the occurrence of cavitation. Moreover, it was observed that the triangular spray cone angle displayed axis-switching phenomena for both fuels. The axis-switching phenomenon is suppressed by using biodiesel. The research also discovered that the triangular biodiesel spray has a longer spray tip penetration and a smaller angle in all view planes. This could be attributed to the higher viscosity and surface tension of biodiesel, as well as the inhibition of the spray axis-switching during the injection, leading to an increase in the spray tip penetration and a decrease in the spray cone angle for biodiesel.

Supercritical water injection in a single cylinder research engine: a PIV study

This work presents the experimental results of a fluid dynamic investigation to characterize the injection of supercritical water in the combustion chamber of an internal combustion engine. Particle Image Velocimetry (PIV) analysis is carried out in an optically accessible 2-stroke Diesel engine. A prechamber, equipped with two optical accesses is connected to the main cylinder through a tangential duct so that the piston stroke induces a swirled motion field with angular velocities typical of light duty engines for automotive application. The engine is equipped with an injection system for the production and injection of supercritical water, with the possibility to independently regulate the injection pressure, temperature, duration, and timing. Tests have then been carried out under different operating conditions to evaluate the impact of the fluid dynamics in the combustion chamber on the water spray. First, the airflow velocity field has been characterized at different engine crank train angles. The water spray has been macroscopically characterized for an injection temperature of 300°C and pressure of 30Mpa. Then, the supercritical water/air interaction has been explored, at different injection pressure, temperature, and Start of Injection (SOI) to provide global information in terms of spray morphology, tip penetration, and velocity vector distribution of the water droplets within the combustion chamber for different injection strategies.

Single hole ammonia spray macroscopic and microscopic characteristics at flare and transition flash boiling regions

As a potential zero-carbon fuel for internal combustion engine to mitigate the greenhouse gas emission, ammonia’s unique flash boiling spray behaviors have not been well understood. In this study, the macroscopic and the microscopic characteristics of the liquid ammonia spray at the flare and transition flash boiling regions were experimentally investigated under different pressure ratios (RP, the ambient over the saturated pressure) and ambient temperatures. The spray macroscopic morphologies captured from the high-speed camera in the flare flash boiling region (RP ≤ 0.47) show that the spray expands significantly in radial direction while that in the transition flash boiling region (0.47 < RP ≤ 1.06) is more contracted in the penetration direction. Additionally, in flare flash boiling region, spray tip penetration and velocity increases generally with the increase of RP, while that in the transition flash boiling region in versus. Furthermore, the microscopic droplet statistics clearly demonstrate show that the most probable droplet diameter moves to a larger value with the increase of RP. The peak probability of droplet size and the droplet number density decreases at larger RP cases, resulting in a more uniformly distributed droplet sizes and an increased Sauter Mean Diameter. Finally, the ambient temperature show limited influence on the macroscopic spray penetration behaviors or the microscopic droplet size distribution, but evaporation is significantly enhanced since at highest ambient temperature, there are minimized droplet number density in some of the test locations.

Ethanol Blend Effects on The Spray Properties of a Biodiesel Fuel by Ambient Pressure Variation

Diesel engine spray nozzles are crucial to pollutant generation and engine efficiency. Nozzle performance can be enhanced by adjusting the nozzle's internals. A successful demonstration of the nozzle would be one in which the spray's outcome was uniformly dispersed throughout a wide area, with the grains scattered similarly. The purpose of this research was to examine how a diesel-ethanol characteristic under normal atmospheric pressure (spray tip penetration, the velocity of spray, and spray angle) and, in general, to assess the performance of biodiesel fuel on diesel engines, a substantial amount of biodiesel and operational expenses for the engine are necessary. It was an experimental approach to the study. The research involved recording spray fuel at the nozzle. Using a 480 fps high-speed camera, we tested BD20, BD20E5, and BD20E10 fuel at three different ambient pressures (1 bar, 2 bar, and 3 bar). The injection pressure was 15 MPa, and the fuel temperature was 28.2 degrees Celsius. Spray tip penetration and spray velocity decreased and spray angle increased after ethanol was added to the mixture, consistent with the studies' findings. Lowered spray tip penetration, slower spray speeds, and a complete spray angle result from the increased ambient pressure.

Theoretical analysis of the spray characteristics of ternary blends of diesel, biodiesel, and long-chain alcohols inside a combustion chamber

The diesel and alcohol blends are potential alternatives to biogenic fuels to reduce biodiesel consumption, which might help reduce toxic emissions. Due to the high-quality requirements for engines, the fuel fundaments in the fluid properties and its impact on the macroscopic spray characteristics. Herein, a study proposed the experimental determination of density, viscosity, and surface tension for ternary mixtures of diesel (D) + biodiesel (B) + 1-hexanol (H) and + 1-octanol (O) at 298.15 K. These properties comply with the limits established by the EN 14214 and ASTM D975 standards. Thus, to extend the impact of these results, a theoretical analysis via CFD is carried out in ANSYS FLUENT ® by considering a macroscopic and isothermal system, which involved the independence tests of meshing and turbulence modeling. The numerical results evaluated the spray tip penetration, spray angle, spray morphology, eddy turbulence, and relation of spray volume and surface spray area at the injection pressure of 90 MPa using the Large Eddy Simulation (LES) model. The behavior of the spray tip penetration and spray angle agree with experimental values reported in the literature for diesel fuel. This condition validates our simulations for biodiesel and ternary blends. Therefore, the use of alcohols and biodiesel as new additives to diesel improves the macroscopic spray characteristics, and some ternary mixtures showed similar behavior to conventional diesel: spray tip penetration (70D5B25O, 70D25B5H, and 70D25B5O) and spray angle (70D25B5H, 70D15B15H, 80D5B15O, and 80D15B5). The mixture of 70D25B5H agrees with both spray characteristics; therefore, this mixture could be considered an alternative fuel to conventional diesel. Hence, this analysis presents the essential elements to visualize the macroscopic spray characteristics and the fluid properties. This knowledge serves as a foundation for elucidating the intricate dynamics of spray during combustion processes and the development of complementary studies aimed at optimizing engine performance.

Analysis of the structure of the atomized fuel spray with marine diesel engine injector in the early stage of injection

This paper presents the results of the experimental research of the atomized fuel spray with the marine diesel engine injector in the constant volume chamber. The specificity of the phenomena occurring in the marine engine cylinder was the reason to use the optical visualisation method in the studies – the Mie scattering technique. This work presents an analysis of the influence of different geometry of outlet orifice and opening pressures of marine diesel injector on the macrostructure of the fuel spray. In the results, it was observed that the increased L/D ratio of the outlet orifice of the injector caused: an increase in the spray cone angle and a decrease in the spray tip penetration in the early stage of injection. Furthermore, it was defined that the characteristic of spray tip penetration over time was power, whereas the spray cone angle over time was a logarithmic function.