Spray Tip 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.

Volume de calda e espetro de gotas no controle de Bidens pilosa e Ipomoea triloba com o herbicida Fomesafen

ABSTRACT Among weed control methods, chemical control using herbicides is one of the most widely employed due to its practicality and efficiency. However, there is still a lack of reliable information regarding the effectiveness of low-volume spraying and the droplet spectrum for contact herbicides, such as fomesafen. The objective was to determine the spray volume and droplet spectrum for applying the fomesafen herbicide and its efficacy in controlling hairy beggarticks (Bidens pilosa) and littlebell (Ipomoea triloba). The herbicide was applied using a CO2-pressurized knapsack sprayer with TT11002 spray tip spaced at 0.50 m, operating at pressures of 100 kPa (very coarse droplets) and 400 kPa (medium-sized droplets) with spray volumes of 35, 70, 140, and 280 L ha-1, obtained by varying the application speed. At the time of application, the percentage of covered area and droplet density (droplets cm-²) were evaluated on water-sensitive paper labels using the DropScope® program. The best control results for hairy beggarticks were achieved when the application was performed with very coarse droplets at a pressure of 100 kPa, with a spray volume between 65 and 280 L ha-1, droplet density exceeding 60 droplets cm-2, and coverage greater than 10%. Fomesafen does not provide effective control of littlebell.

Rapid analysis of untreated food samples by gel loading tip spray ionization mass spectrometry.

Rapid, efficient, versatile, easy-to-use, and non-expensive analytical approaches are globally demanded for food analysis. Many ambient ionization approaches based on electrospray ionization (ESI) have been developed recently for the rapid molecular characterization of food products. However, those approaches mainly suffer from insufficient signal duration for comprehensive chemical characterization by tandem MS analysis. Here, a commercially available disposable gel loading tip is used as a low-cost emitter for the direct ionization of untreated food samples. The most important advantages of our approach include high stability, and durability of the signal (> 10min), low cost (ca. 0.1 USD per run), low sample and solvent consumption, prevention of tip clogging and discharge, operational simplicity, and potential for automation. Quantitative analysis of sulfapyridine, HMF (hydroxymethylfurfural), and chloramphenicol in real sample shows the limit-of-detection 0.1μgmL-1, 0.005μgmL-1, 0.01μgmL-1; the linearity range 0.1-5μgmL-1, 0.005-0.25μgmL-1, 0.01-1μgmL-1; and the linear fits R2 ≥ 0.980, 0.991, 0.986. Moreover, we show that tip-ESI can also afford sequential molecular ionization of untreated viscous samples, which is difficult to achieve by conventional ESI. We conclude that tip-ESI-MS is a versatile analytical approach for the rapid chemical analysis of untreated food samples.

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.

In vitro evaluation of intersubject variability in pediatric intranasal drug delivery using nasal spray suspension products

Evaluation of the regional intranasal delivery of locally acting drugs in children is challenging. Anatomical nasal airway replicas potentially can provide a robust pre-clinical tool to test the performance of devices and formulations. However, there is often a challenge in identifying the nasal geometries that can reasonably be indicative of in vivo regional mass distribution of administered drug. This in vitro study was designed to investigate the regional intranasal drug delivery in 20 children, 2–11 years old (50% 2–6 years old and 50% female), using two commercially available suspension nasal spray products with different nozzle designs, plume characteristics, and active pharmaceutical ingredients. High-resolution computed tomography scans of the sinonasal region of pediatric human subjects with healthy nasal airways, reviewed and scored by a head and neck surgeon, were used to develop 20 three-dimensional (3D) replicas of the nasal airways. The 3D replicas were segmented into the two regions: anterior and posterior to the internal nasal valve (INV). They were then rapid prototyped in high clarity rigid plastic (Accura ClearVue). Each side of the septum of the 20 subjects was examined separately, resulting in 40 singular nasal cavities. A nozzle-specific spray tip holder was designed for each case to ensure consistent administration (insertion length, sagittal angle, and coronal angle) in all replicates. The wide range of posterior drug delivery observed in the forty geometries indicated significant intersubject variability in pediatric intranasal drug delivery. Three nasal geometries representing low, medium, and high levels of drug delivery to the target region, posterior to the INV, were chosen from the 40 nasal cavities. Our vision is that these three nasal geometries can potentially be beneficial in determining whether performance differences between test and reference nasal spray products are present that may affect their bioequivalence in children. They also may be useful when applied in parallel with similar adult nasal geometries, previously developed following a similar procedure, to provide additional insights into pediatric nasal drug delivery with innovator products in children in lieu of extending clinical studies to include pediatric subjects.

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.

An investigation on pyrolysis characteristics of low-sulfur heavy fuel oil spray under diesel engine-like conditions

The pyrolysis characteristics of low-sulfur heavy oil fuel (HFO) spray under diesel engine-like conditions were investigated for the first time using both experimental and numerical methods. The high speed diffused back-imaging method was adopted to measure the macroscopic features of the low-sulfur HFO spray, and its products were sampled and analyzed by the gas chromatography with mass spectrometry. The low-sulfur HFO spray behaves as a quasi-evaporating spray under high temperature conditions, integrating the characteristics of evaporating and non-evaporating sprays. The increase of temperature shows little effect on its penetration characteristics, but a great effect on the vapor distribution. The low-sulfur HFO spray can pyrolyze at the temperature below 650 K due to the high heating-up rate and ambient pressure, and the aromatics contained in it are easy to pyrolyze, producing some oxygenate and amide components. Based on the experimental results, an integral pyrolysis model with multi-component evaporation and pyrolysis was established and implemented into the Eulerian-Lagrangian framework to simulate the low-sulfur HFO spray, and its predictions agree very well with the experimental results. The pyrolysis shows a large effect on the HFO spray evolutions. Ignoring the pyrolysis process would underestimate the droplet temperature and distribution number at the HFO spray tip and overestimate the vapor concentration of heavy-end hydrocarbons, because most of them are trapped inside the droplet enclosed by the pyrolytic residues.

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.

Taxa de aplicação e pontas associados à eletrificação de gotas afetam a qualidade da pulverização em feijoeiro

ABSTRACT The objective of this work was to evaluate the application efficiency of different nozzle tips associated with increasing application rates. A field experiment was conducted in a factorial 3 × 4 randomized block design with four replicates. The first factor consisted of three types of nozzle tips (simple flat fan, hollow cone, and hollow cone with the electrification of the drops), and the second factor constituted the four application rates (50, 100, 200, and 250 L ha-1). Electrostatic technology and a hollow cone tip increased the deposited volume on leaves on the upper and medium strata of the common bean plant, regardless of the application rate used. The increase in the application rate increased the volume of spray solution captured in the upper, medium, and lower strata, the drop density, the volumetric median diameter (VMD), and the percentage of foliar coverage, regardless of the spray tip evaluated. The percentage of leaf coverage on the adaxial and abaxial leaf was not influenced by the simple fan or hollow cone spray tips, with or without the association of electrostatic technology.

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.

Multiphase simulation of sustainable nanoenhanced ionic liquid coolants for improved thermal performance in Ti–6Al–4V alloy drilling

Extensive research has been conducted by the manufacturing industry to enhance the efficiency of drilling processes by focusing on the utilization of nanoenhanced cutting fluids that possess excellent heat conductivity. Due to their eco-friendliness and adaptability of physical and chemical properties, ionic fluids offer enormous potential for application as cutting fluids. This study investigates the computational fluid dynamics analysis of the heat transfer performance of various ionanofluid pairs dispersed with nanoparticles as cutting fluids in the drilling process using Ansys Fluent software. For this purpose, 1-Hexyl-3-methyl-imidazolium-tetrafluoroborate is considered the ionic fluid, and its thermal behavior is examined by dispersing it with nanoparticles of copper, silver, and multiwalled carbon nanotubes (MWCNT) at different particle volume fractions and Reynolds numbers. The workpiece is composed of an alloy of titanium Ti–6Al–4V, while the drill bit is made of tungsten carbide-cobalt. It is observed that the ionic nanocoolant mist emanates from the spray tip and moves towards the drill bit-workpiece interface. Initially, the coolant's velocity is greatest close to the orifice, and as time passes, it approaches the drilling space. The data indicates that the spraying velocity of the coolant augments over time and that it disperses heat at the tool-chip interface. The results help us validate the flow and interaction of ionanocoolant with the drilling zone. With a rise in the volume fraction of added nanoparticles and Reynolds number, the results indicated a significant decrease in the drilling temperature. With a higher particle volume fraction, the MWCNT-ionic coolant combination decreases the drilling temperature of pure ionic liquid by 25.64 %. The copper, silver, and MWCNT ionanofluids enhance the average heat transfer coefficient of pure ionic coolant by 35.14 %, 47.42 %, and 62.75 %, respectively. In addition, MWCNT nanocoolants demonstrated improved thermal performance and heat removal rate in comparison to copper and silver ionanocoolants.