Spray Angle Research Articles

Estimation of spray flow characteristics using ensemble Kalman filter

Spray flows are widely used in several industrial applications, such as combustion engines. Accurate measurement of spray flow characteristics requires sophisticated equipment and techniques. In recent years, the discrete droplet method (DDM), which analyses droplet scattering, has become a mature technique and has been applied to various analyses. We propose an estimation system based on particle image velocimetry (PIV) measurements and an ensemble Kalman filter, together with DDM, to efficiently investigate spray flow characteristics. The proposed method performs data assimilation on the velocity distribution in a two-dimensional cross-section obtained by PIV to estimate the characteristics of the spray flow in three dimensions. In this study, the system was constructed so that droplet particle is ensembled during data assimilation to estimate the droplet diameter distribution indirectly. The proposed method can be used to estimate the spray velocity and droplet size distribution. The numerical solution obtained using DDM was used as a criterion for assimilation and validated by conducting twin experiments. The results showed that, in terms of spray velocity, the estimation error for the velocity component parallel to the main flow was 2% and that for the velocity component perpendicular to the main flow was around 10%. Finally, the velocity and particle size distributions of the spray stream and the three-dimensional droplet distribution were estimated by assimilating the velocity distributions measured by PIV. This technique predicts the spray angle and droplet size distribution from the two-dimensional velocity field of the PIV only and is expected to contribute to the development of injectors and atomizers.

Metal Coating by TIG Arc Deposition Method

Metal (Aluminum) coating was prepared on stainless steel substrate by arc deposition method using TIG Welding machine. Plasma spray is a type of metal coating that is widely used in the industry and its preparation cost is expensive. It is also the most flexible method to apply a wide variety of coatings on a substrate. To reduce the cost of the set-up, the plasma will be generated by using a TIG welding machine to replace the plasma spray. The use of powder which is aluminium as a coating raw material causes almost no restrictions on the use of coating materials used in the plasma melting process. The changing parameters in this experiment are the angle nozzle powder and the flow rate of the working gas which is Argon (Ar) gas and the substrate used is SUS304 stainless steel and the feedstock powder used is Aluminium (Al) powder with an average size of 5 μm. Flow rate used in this study was 10,20 and 30 l/min of Ar and the powder nozzle spray angle was 45°, The live image, diameter, thickness, and surface roughness of the coatings were systematically analyzed using LEXT OLS5000 3D Measuring Laser Microscope.

Smartphone image-based framework for quick, non-invasive measurement of spray characteristics

Agricultural spray nozzles are small yet key components for delivering agrochemicals to the target surface. Their complexity demands specific assessment to guarantee the spray quality. The traditional equipment measures spray characteristics accurately; however, it can be time-consuming and invasive. An emerging method for agricultural assessments is image processing. Therefore, our goal was to develop an innovative smartphone image-based framework to analyze spray characteristics (angle, single distribution and solid stream jets) and detect poor spray nozzles under indoor or outdoor environments. We used flat fan and hollow cone nozzles, with three sizes and three working pressures. A mobile phone with 12 MP was used to capture spray images. The images were automatically stored and processed using a cloud computing platform. Spray angle was estimated by finding edges in binary images and using Hough transform function. Single spray distribution shape was characterized by extracting the pixel grayscale value profile across a horizontal line in three regions of the image. Finally, solid stream jets were detected using a function to calculate grayscale peaks. The actual spray characteristics were measured using an automatic horizontal patternator with 120 collectors (25 mm grooves). As a result, image-based spray angle mean absolute error (MAE) and mean absolute percentual error (MAPE) were 4.45º and 4.40%, respectively, leading to an underestimation in most cases. Specific regions of the image accurately resembled the measured spray distribution shape, except for hollow cone nozzles when working at low pressures. Moreover, solid stream jets were correctly detected at three different flow rates. Our framework was validated for both indoor (laboratory) and outdoor (field) conditions and had similar results in detecting poor spray nozzles. The only restriction was the combination low/medium pressures with small nozzle sizes. Therefore, our insights absolutely contribute for quick, non-invasive measurements of spray nozzles characteristics through a digital approach and open pathways towards affordable and flexible methods for agricultural assessments.

Influence of Elevated Fuel Temperatures On the Spray Characteristics of Gasoline - Ethanol Blends

Abstract In this study, the effect of elevated fuel temperatures on the spray characteristics of gasoline-ethanol blends were studied in an optically accessible constant volume spray and combustion vessel. MAHLE SmartHeat® is a fuel heater located directly upstream of the fuel injector. High speed images of the spray injected from a six-hole gasoline direct injection injector typical of a side-injection engine were captured with shadowgraph imaging technique. Two fuel blends, gasoline with 10% ethanol (E10) and 85% ethanol (E85) were investigated at ambient conditions of 1 bar, 45°C and 4 bar, 180°C at an injection pressure of 100 bar. Fuel temperatures were varied from 75 to 250°C. A comparison of the near nozzle and the global spray characteristics was made for the two fuels in the range of fuel temperatures selected. Results showed that flash boiling leads to two primary effects for the two fuel blends: (i) an appreciable increase in spray angle near the exit of the nozzle followed by (ii) a decrease in spray angle downstream of the nozzle due to the interaction of the plumes and the collapsing of the spray. Furthermore, for both fuel blends, upon flash boiling, entrainment and mixing were reduced downstream of the nozzle because of the collapse of the spray. To reduce this effect, nozzle orientations and geometries should be modified.

Experimental evaluation of individual effects of water mist spray characteristics on thermal radiation attenuation using twin‐fluid nozzles with full‐cone spray pattern

AbstractIn this study, the effects of water mist spray characteristics on thermal radiation attenuation were experimentally investigated using five types of external and internal mixing twin‐fluid nozzles with a full‐cone spray pattern. To the best of our knowledge, this may be the first attempt to experimentally examine the separate effects of water mist spray characteristics on thermal radiation attenuation. Water and air supply pressures were measured, and their values were 1.3–55.5 and 29.8–316 kPa, respectively. The Sauter mean diameter and volume median diameter of the water mist were measured to be 20–99 μm and 21–108 μm, respectively. The spray angle and width of the water mist were approximately 20° and 110 mm, respectively. The thermal radiation attenuation afforded by the water mist discharged from the twin‐fluid nozzle increased with increasing water and air flow rates and decreasing droplet sizes. Within the experimental range, the thermal radiation attenuation was approximately 6.9%–28.4%. Based on experimental data, the effects of the water flow rate and droplet size on thermal radiation attenuation were examined independently. The dependence of the thermal radiation attenuation on the droplet size was greater than that on the water flow rate.

Study on Temporal and Spatial Distribution and Transport Characteristics of Dust in New Composite Spraying Slurry

In view of the problems of traditional spraying technology, such as complex processes, high costs, large dust amounts, and poor air leakage effects, a new composite spraying slurry is proposed in this paper, which takes clay as the main base material and uses water pressure and wind pressure to ensure intrinsic safety. Firstly, the airtightness, bending resistance, and viscosity of the spraying material were measured in the laboratory; secondly, the gas–liquid–solid three-phase flow process involved in the spraying process was simulated by using the CFD-DPM method, adopting the Eulerian two-fluid model for continuous gas–water two-phases and the discrete phase DPM model for dust generation, and the transport, diffusion, and full space-time distribution characteristics of dust generation were studied. The research shows that: (1) the new composite slurry spraying material made of clay as the main material is made by adding a small proportion of cement and engineering fiber to increase the toughness of the material, and finally, determining the mass ratio of the composite material as follows: clay: cement: additive: engineering fiber = 84:14:1.85:0.15. It has good sealing and bending resistance and good adhesion; (2) the water phase distribution under the action of spray determines the distribution of solid-phase dust, and the distribution area of dust is similar to that of the water phase; (3) under the action of spray, the area at the bottom of the roadway is covered by dust flow, and the dust in this area is obviously stratified. The particle size of the dust gradually decreases from bottom to top. The large particle size dust is deposited at the bottom, while the small particle size dust is suspended at a certain height, and the diffusion area gradually increases; (4) the effect of spray angle on dust is mainly manifested in the initial dust flow shape and dust diffusion time. The larger the spray angle, the faster the diffusion; (5) when the water velocity at the nozzle outlet is large, the dust concentration is low in the whole area, but in areas higher than 1.5 m, the PM2.5 concentration also increases with the increase in water flow. The dust suppression effect of larger a water flow is mainly reflected in the bottom area, and the disturbed surrounding airflow can make PM2.5 diffuse to higher areas.

Methane slip reduction of conventional dual-fuel natural gas diesel engine using direct fuel injection management and alternative combustion modes

Alternative combustion mode and change of spray geometry show potential for methane slip reduction in a dual fuel diesel-natural gas internal combustion engine. Three combustion regimes are simulated; a conventional diesel methane dual-fuel combustion and two modes of reactivity controlled compression ignition (RCCI) with early (EIRCCI) and late (LIRCCI) injections. Methane is injected as the premixed fuel into the port and diesel as direct-injected fuel in all combustion modes. The start of direct fuel injection (SOI) is used as the combustion management tool, swiping from misfiring to knock limits at part loads.By switching combustion mode from conventional (CDF) to LIRCCI and EIRCCI, methane slip is reduced by 12% and 33%, respectively. SOI is used effectively to manage methane slip in any combustion mode, but the effect is more substantial in the EIRCCI mode.Emission results support methane slip trends’ observations. Nitrogen oxides (NOx) emission is increased in CDF by advancing SOI and decreased in both the LIRCCI and EIRCCI modes. Compared to CDF, late and early injection RCCI modes produce 417% and 67% more soot. Also, results show that high levels of methane slip in CDF can be reduced to some extent without any geometry modification by SOI management.Three diesel spray angles (SAs) of 60, 90, 120° are examined. Minimum methane slip is obtained when the SA is towards the squish area, and maximum methane slip is obtained when the SA is towards the piston bowl. Increasing SA from 60 to 90 and 120° results in a 16.4% and 42.5% reduction of methane slip.

Short fiber spraying process of all‐oxide ceramic matrix composites: A parameter study

AbstractFiber spraying processes have been established for polymer matrix composites for decades. In this study, we transferred an automated fiber spraying process to short fiber bundle‐reinforced Nextel 610/ Al2O3‐ZrO2 oxide fiber composites (SF‐OFC). The effect of the processing factors travel height, spray angle, and movement speed on the specimen strength was analyzed in a full factorial experimental design. As a result, the significance of the travel height as well as the interaction between travel height and movement speed was demonstrated. Furthermore, the influence of the fiber length (14, 28, 56, and 112 mm) on the bending stress and strain was investigated. Independent of the used fiber length, the SF‐OFC exhibited an excellent quasi‐ductile fracture behavior with bending strains in the range of .6% and in‐plane isotropic material properties. The average bending strength increased from 133 ± 27 MPa with 14 mm fiber reinforcements to 163 ± 29 MPa with 112 mm fibers. The achieved bending strengths clearly exceeded the off‐axis properties of currently used fabric‐reinforced OFC. These properties, combined with the excellent drapability and cost effectiveness, make the novel material highly promising for industrial applications such as flame tubes, burner nozzles, kiln furnitures, or foundry components.

Investigation on the effect of ventilation on string cavitation patterns in diesel nozzles

Aiming at the complicated vortex problem that affects the flow stability of diesel engine nozzles, this paper focuses on the effect of ventilation on the string cavitation patterns in the nozzle hole with a self-built scale-up test bench. Hole-to-hole string cavitation is not stable without bubbles, and the ventilation can improve the situation. Relatively speaking, the position of hole-to-hole string cavitation in the SAC volume changes significantly with the bubble content. In contrast, the needle-originated string cavitation is stable in the vortex channel. Only if there are many bubbles, the cavitation pattern changes to hole-to-hole string cavitation or string cavitation originating from the upper wall of the hole inlet. At this point, the corresponding atomization morphology changes, and the spray angle decreases significantly. It is verified that there is a one-to-one correspondence between the cavitating pattern and the spray angle near the hole.

Experimental study on the macroscopic characteristics of air-assisted diesel spray

ABSTRACT This study aims to examine the effects of ambient pressure and injection parameters on the macro-characteristics of air-assisted diesel spray. To illustrate the morphological variation of spray and the formation of vortex ring, the spray diffusion angle was defined. The results indicate that high ambient pressure hinders the radial and axial development of spray and delays the formation of vortex ring. As the ambient pressure increased from 1 bar to 2 bar, the formation of vortex ring was delayed by approximately 0.5 ms. Extending fuel injection duration reduced the spray penetration and increased the far- and near-field spray angles; however, the spray diffusion angle decreased. Increasing fuel injection pressure produces more small-sized droplets owing to enhanced droplet breakup, which decreased the spray penetration and facilitated the lateral diffusion of droplets. Increasing mixture injection duration did not affect the spray penetration; however, the variation of the diffusion angle was slowed down after the mixture injection ended. The insufficient fuel-air interval cannot adequately decelerate the injected fuel droplets, resulting in large penetration and weak lateral diffusion. And there was a critical interval between 1.0 ms − 3.0 ms in this study, after which the fuel droplets could be decelerated sufficiently.

Design and performance analysis of a Swirl Pintle injector for a 1 MWth pressurized oxy-coal combustor

Pressurized Oxy-coal combustion has the potential to achieve high thermal efficiency by recovering the latent heat of steam from flue gases and providing options for up to 95% carbon capture. This study proposes a novel burner technology for pressurized oxy-coal combustion and investigates its operability. Three burner versions are designed and tested; no swirl, swirl numbers 0.9 and 1.2 to identify optimum design parameters and performance. A commercially available Dantec Dynamics software is used to conduct the shadowgraph experiments to observe burner performance. Coal water slurry is used as fuel with three different slurry ratios where the coal percentage by weights were 30, 40 and 50. Droplet size, distribution, spray angle and jet breakup lengths are measured and analyzed to quantify the performance. The study found that increasing the swirl number enhanced atomization. Implementing swirlers allowed the jet to spread through faster primary jet separation, thus improving atomization. In addition, higher slurry ratios improved the generation of smaller particles. However, it was also found that excessive increases in oxidizer momentums negatively impact the atomization process by jet shrinkage. The study concluded that operating a pintle burner at 1.2 swirl conditions with a 40/60 slurry ratio produces optimum performance.

Effects of Groove Structure on Spray Characteristics of a Throttleable Pintle Injector

Throttleable rocket engines are used for various purposes, including vertical landing of launch vehicles and soft landing on the surface of celestial bodies. The use of a throttleable pintle injector is a representative throttling method because of its ability to maintain the spray characteristics under different throttling levels. However, previous studies have reported changes in the spray characteristics of gas–liquid pintle injectors with varying throttling levels. To address this issue, a pintle tip with groove structure was developed in this study. Cold flow experiments were performed using normal and grooved pintle tips for a gas–liquid pintle injector, and the spray angle and average droplet size of the pintle injector were measured and compared. By changing the momentum and structure of the radial flow with added grooves, the spray angle increased and the droplet size decreased. The results indicate that adopting a grooved pintle tip can improve the spray characteristics of a pintle injector in terms of its correlation with combustion performance, particularly at low throttling levels. Additionally, a grooved pintle tip reduces the changes in spray characteristics under varying throttling levels, which is advantageous from the perspective of design simplicity.

Spray characteristics of fouled gasoline direct injectors under flash boiling and sub-zero temperature conditions

This study investigated the spray characteristics of a fouled injector under different ambient pressures, fuel temperatures, and flashing ratios. Four fouled injectors and a clean injector were used to analyze the effects of deposits on spray characteristics. A fouled injector, showing the greatest difference in spray characteristics compared to a clean injector, was selected as a representative fouled injector and analyzed. The near-field and far-field spray visualization were performed by using the Mie-scattering imaging technique. Quantitative indices, such as the spray angle, penetration length, and sharpness intensity, were defined to compare the spray characteristics of the fouled and clean injectors. These quantitative indices were calculated using the MATLAB image processing tool. Deposits formed differently even under the same engine operating condition, such that the spray structure was different depending on the fouled injector. In the near-field spray visualization, there were relatively large droplets and long ligaments in the fouled injector compared to the clean injector due to the low atomization performance.

Influence of Spray Control Parameters on the Performance of an Air-Blast Sprayer

Orchard plant protection machinery in China still has a low application efficiency. Air-blast sprayers represent the primary development direction of pesticide applications in orchards. The spray control parameters have to be matched to the tree canopy status to achieve precise results. In this study, a vertical patternator was used to determine the accuracy of spraying fruit trees. The influences of three control parameters (blower speed, spray angle, and spray distance) on the spray performance of the air-blast sprayer were analyzed, and the volume of the spray was measured in collection plates at different heights. The quantitative relationship between the overall collection volume and the critical height collection volume was obtained for different parameter values, and the combined effects of any two control parameters on the collection performance and the position of the optimum collection area were obtained. The regression model describing the relationship between the collection volume in the critical height range and the three factors was established, and the main effects of the control parameters were determined. The results showed that if one parameter remained constant, the correlation between the other two parameters was non-significant. The collection volume in the critical height range increased initially and then decreased as the spray distance increased. The maximum collection volume was obtained at a spray distance of 1.762 m. The regression model can be used to obtain the optimum values of the parameters.

Study on Characteristics Optimization of Combustion and Fuel Injection of Marine Diesel Engine

The emission requirements of diesel engines are becoming increasingly strict and reducing emissions has become the key technology. In view of this development trend, the influence law of fuel injection on emission is studied in this paper. Numerical studies were performed to analyze the structural parameters of fuel injection system on combustion and emission characteristics of marine diesel engines. The numerical modelling was validated based on single-cylinder diesel engine tests and fuel injection tests. After investigating the single structural parameters on the fuel injection characteristics, the orthogonal method was used to design the double-parameter structural optimization scheme of the fuel injection system. There are 22 optimized cases selected to further investigate using the CFD method by visualizing scalar distributions in cylinder, which was helpful to explain the reason of pollutant formation. Comprehensively comparing the performance of each fuel injection system’s structural optimization scheme, moderate reduction of the discharge valve chamber volume and high-pressure tubing diameter would increase injection mass, along with faster injection rate and boosted injection pressure, leading to reduced Sauter mean diameter (SMD). Considering pollutant emission characteristics as well as economic and power concerns, case D6 with spray angle enlarging 5° showed best performance. Compared with the original condition, there was no NO deterioration and large reduction of soot emission by 65.4%, along with fuel consumption being lowered by 2.18% and more indicated power, by 2.21%. Therefore, reasonable optimization of spray angle can improve power, economy and emission performance simultaneously.

Influence of Micro- and Macrostructure of Atomised Water Jets on Ammonia Absorption Efficiency

Ammonia has a very wide range of applications. Its worldwide production exceeds 230 million tonnes per year. Due to its properties, ammonia causes a serious threat to human life and health when released uncontrolled into the environment. Research carried out in the word shows that this substance may be effectively neutralised by absorption in water. The aim of research described in this paper is to determine the influence of key parameters of the micro- and macrostructure of water streams on the course of the ammonia absorption process. During the studies, different types of water nozzles were used, with similar efficiency and supply pressure, but characterised by different parameters of the micro- and macrostructure of the produced stream. The experiments were divided into two stages. In the first one, the macro- and microparameters of the streams were measured, while in the second one, the changes in ammonia concentration were established during delivering spray jet generation by different nozzles. Among the basic parameters of the macrostructure, the spray angle and liquid distribution in the jet (spray intensity) were determined, while for the microstructure, the droplet size distribution and mean droplet diameters were measured. Ammonia concentration was measured by means of a photoionisation detector (PID). In order to evaluate the absorption efficiency of different water spray jets, the apparent absorption rate (kp) and the half-time of concentration reduction (t½) in the kinetic range were established. The study has confirmed that atomised water jets are an effective method for neutralising ammonia released into the environment. The research has a practical aspect and shows that the structure of atomised water streams influence the course of the absorption process. Increasing the spray angle in a conical stream leads to an improvement in the quality of water atomisation and helps increase ammonia absorption. Moreover, it was also observed that for the absorption of spatial ammonia clouds, use should be made of nozzles generating streams with full spray cones and high uniformity of spray and dispersion.

Mechanism insight of shielded methane non-premixed jet flame extinction with water mist: OH-PLIF visualization and quantitative analysis of critical fire extinguishing

Natural gas leaks from pipeline systems or storage sites may highly lead to a fire safety incident as well as a potential major hazard in industries or residential. The leaked jet flame commonly sheltered by an obstacle is more difficult to be extinguished as the result of a reduction in effective extinguishing agent flux and potential re-ignition. Especially in cases where the flame is heavily obscured by obstacles, the interaction of the extinguishing agent and flame can be very different from the unobstructed situation. This study aims to determine the critical characteristics of a water mist to extinguish a shielded non-premixed jet flame with the flame structure visualization of hydroxide planar laser-induced fluorescence (OH-PLIF) and quantitative parametric analysis. The effect of obstacles on water mist and a jet flame is firstly quantitatively evaluated by flame obscuration ratio kf and maximum effective mist ratio k in critical fire-extinguishing cases. Flame dynamical behavior from the base of the flame upwards to extinction is found when the flame Froude number Frf > 0.74 and kf > 0.75. Finally, the preferred water mist nozzles with larger spray angles might have more effective fire extinguishment ability typically under the cases of k < 0.5 and kf > 1.0. This study would be valuable for the optimum design of water mist systems in natural gas leakage incidents under shielded conditions.

Analysis of droplet characteristics and cooling lubrication effects in MQL milling of 316L stainless steel

The infiltration and cooling effect of lubricant droplets in the cutting zone largely depend on setting minimum quantity lubricant (MQL) system parameters appropriately. The study determines the optimal spray angle and spray distance relying on the geometric position relationship between the nozzle and the overall cutting zone. A numerical model that combines computational fluid dynamics (CFD) and discrete phase model (DPM) is presented to simulate droplet transport process for dynamic milling and one-tooth milling by flow field distribution and droplet characteristics. The influences of different spray distances and spray angles on the infiltration process and cutting tool temperature are analyzed. The experiments aimed at verifying the results of the analysis are conducted by measuring cutting force, cutting temperature, surface roughness, surface microtopography and tool wear. The result indicates that the spray distance has a significant impact on the jet divergence, and insufficient lubrication or excessive lubrication is effectively avoided with the optimal cutting distance. Spraying in the direction of cutting-out promotes the accessibility of the lubricant and greater concentration of droplets in the cutting zone, especially later in the cutting process, which results in increased infiltration, reduced friction, and improved heat dissipation. Moreover, experiments demonstate that the optimal state of jetting in the direction of cutting-out is 46 °C lower than that of dry cutting, the surface roughness is reduced by 19.8%, and the wear amount is reduced by roughly 34%. This study has a better understanding of the setting of spray distance and spray angle in MQL milling and the development of equipment, which provides theoretical guidance for the optimization of MQL system parameters in practical applications.

Numerical analysis of injection and spray characteristics of diesel fuel and rapeseed oil in a diesel engine

Vegetable oil-based biofuels are promising carbon-neutral fuels to replace fossil fuels. The study focuses on a comparative analysis of injection and spray characteristics of DF and RO and the relationship between spray and emission formation. Steady nozzle flows were simulated in Ansys Fluent. Free sprays were modeled with 0D spray models, and the relationships between atomization parameters and TKE at the orifice exit were analyzed. Sprays of DF/RO blends in real combustion chamber conditions were simulated with a multi-zone spray model in DIESEL-RK. The influence of RO content on fuel atomization and fuel-air mixture formation were analyzed. Compared with DF, RO has lower injection velocity and TKE at the orifice exit. The empirical correlations of mean droplet diameters and spray angle with TKE were developed by using a complex TKE/ν 0.5 with correlation coefficients above 0.988. The increase of the RO content from 0 to 100% leads to a reduction in spray angle by 24% and an increase in spray tip penetration by 15.5%, SMD by 62.1%, and the mass fraction of fuel injected onto the combustion chamber walls from 17.1 to 42%. A correlation between NOx emissions and SMD was fitted with a correlation coefficient of 0.9968.

Injection Properties According to the Inner Shape of Metal Additive Layer Manufactured Coaxial Injectors

The application of three-dimensional (3D) printing technology in rocket engine development has numerous benefits considering cost and time. Among the various techniques of 3D printing, the selective laser melting method has the advantage of being able to manufacture complex structures and process multiple materials. In this study, five types of coaxial injectors with different internal configurations were manufactured using metal 3D printing. To confirm the atomization and mixing performance according to the structure of each injector's oxidizer and fuel post, a cold flow test using water and air was performed under a wide range of experimental conditions. As a result of analyzing the injection pressure drop, discharge coefficient, spray pattern, breakup length, and spray angle, the shape of the oxidizer post had a significant influence on the performance of the injector. In comparison, the effect of the fuel post structure was relatively small; however, there was a meaningful difference in the breakup length and spray angle depending on the direction of rotation.