Spray Cone Research Articles

Multi-objective optimization of the geometric parameters of a pressure-swirl nozzle

ABSTRACT The geometric parameters of the pressure-swirl nozzle demonstrate a significant effect on the atomization performance such as the spray cone angle and mass flow rate. However, these objectives are incompatible, and obtaining a nozzle geometric parameter that optimizes all the atomization performances is difficult. The effectiveness of the nozzle optimization process is typically low, resulting in high costs. To this purpose, an enhanced CBSO-Kriging surrogate model was developed to solve this expensive black box problem, and the spray cone angle and mass flow rate were optimized using a multi-objective optimization algorithm. Firstly, the optimal Latin hypercube sampling method was used to generate 65 sets of sample points, and the corresponding response values were calculated using CFD simulation. The established surrogate model of atomization performance can predict the atomization characteristics of the nozzle with arbitrary shape. The correlation between the key geometric parameters and the spray cone angle and the mass flow rate was determined on this basis. Then, to find the optimal geometric parameters for the nozzle, the NSGA-II algorithm was used. In comparison to the initial model, the optimization results show that the spray cone angle and mass flow rate increased by 4.26% and 37.74%, respectively.

Flashback-induced flame shape transition in a two-stage LPP aeronautical combustor

Large-Eddy Simulations were performed to study the flashback-induced flame shape transition of a lean premixed M flame in a staged liquid-fuelled aeronautical lean-burner, as observed experimentally. The BIMER combustor is a Lean Premixed Prevapourised (LPP) burner composed of two stages, each with its own injector and swirler: the main outer stage, called multipoint, uses jet-in-crossflow injection to achieve the LPP regime, while the central stage, called pilot, uses a pressure swirl injector to create a hollow cone spray to stabilise the flame. During LPP operation, this M flame presents a strong acoustic activity, promoting a periodic flashback of its leading edge. When, aiming to stabilise the flame, the pilot injection is increased and the multipoint injection decreased, the oscillating leading edge (due to the longitudinal acoustic perturbations) attaches to the pilot spray, changing the flame into a Tulip shape. Two phenomena were identified as being the most relevant causes of this flame shape transition. First, the leading edge position and the thermoacoustic instability amplitude are directly linked to the combustion chamber final temperature. The higher the temperature in the chamber, the more upstream the leading edge stabilises, and the higher the acoustic oscillation amplitude, both increasing the risk of a successful flashback. Second, the injection regime with high pilot injection allows the leading edge to attach to the pilot spray, as the flame only transitions when the pilot spray is sufficiently high. The higher the pilot fuel flow, the higher the amount of fuel sprayed in the critical region where the flame might attach for a transition to the Tulip shape. Therefore, as the change in injection regime is the main mechanism lean staged burners use to reduce emissions while increasing operability, this works shows that an M flame is unsuitable to such burners with similar aerodynamic topology and properties.

Recent Advances in Fuel Additives and Their Spray Characteristics for Diesel-Based Blends

The spray characteristics play a crucial role in determining the performance and emissions of compression ignition (CI) engines at the pre-combustion stage. With the advent of many types of alternative fuels and their blends with diesel, it is necessary to investigate the effect of fuel properties and various injection conditions to determine the penetration length, spray cone angle and spray area for a viable fuel with similar or better dispersion characteristics to diesel. Hence, this study reviews and summarizes the spray visualization techniques, along with in depth analysis of macroscopic spray properties of various fuel blends with diesel. It was found that higher injection pressures typically led to higher penetration lengths, better atomization with reduced Sauter mean diameter. Liquid properties such as viscosity, surface tension, and evaporation as well as structural properties play a crucial role in spray formation in fuel blends with various types of alcohols, ethers, biodiesel, aliphatic, aromatic, as well as nanoparticle additives. This review compares these fuel additives and their types to present a comparative study with diesel to determine the ideal conditions with minimal changes to the engine for replacing diesel with a sustainable fuel consisting of better combustion efficiency due to its enhanced spray characteristics.

Research on fuel spray characteristics of coal-made Fisch-Tropsch process diesel/methanol

ABSTRACT Fuel spray characteristics have a big influence on the combustion process and pollutants of diesel engines. The physical characteristics of fuel such as latent heat of vaporization, density and viscosity are also changed when methanol is added to the fuel, resulting in changes in fuel transport characteristics and spray characteristics, which affect the combustion process. A high-pressure common rail spray characteristics visualization platform was built to assess the spray characteristics of diesel, Fischer-Tropsch process diesel and Fischer-Tropsch process diesel mixed with 5%, 10% and 15% methanol. The spray penetration distance, spray projection area and spray cone angle of the five fuels were measured under various injection pressures and back pressure conditions. In addition, the influence of the physical characteristics of the fuels on the spray characteristics was analyzed. The results showed that the spray penetration distance of Fischer-Tropsch diesel/methanol blends changed by about 2%, the spray cone angle elevated by 1%-5%, and the spray projected area increased by 10%-23% when the back pressure ranged from 120 to 160 MPa. When the back pressure was constant and the injection pressure was increased from 120 to 160 MPa, the spray penetration distance of Fischer-Tropsch process diesel/methanol blends increased by about 13%, the spray cone angle increased by about 4%, and the spray area increased by 9% to 33%. Our results provide a basis for the application of Fischer-Tropsch process diesel/methanol blends in diesel engines.

Water–Pesticide Integrated Micro-Sprinkler Design and Influence of Key Structural Parameters on Performance

The use of pergola trellis crops has led to a need for irrigation and the spraying of pesticides. Thus, a new integrated micro-nozzle was designed to provide water and pesticides. The structural parameters that affect the irrigation performance were selected based on the working principle of the sprinkler. They included the outlet diameter, refractive surface angle, and the distance from the outlet plane to the refractive surface (cone hole distance). The structural parameters that affect the performance of spraying pesticide included the number of diversion chutes, nozzle diameter, and nozzle outer cone angle. The structural optimization of the water–pesticide integrated sprinkler was determined by a single-factor and a three-factors four-levels orthogonal tests. The indices used to evaluate the performance of the sprinkler were irrigation flow rate, wetted radius, and uniformity coefficient. Those used to evaluate the performance at spraying pesticides included the flow rate of spraying pesticides, spray cone angle, and relative size range of the droplets. The entropy weight and the extreme difference analytical methods were used to process the test data. The main order of the influence of key structural parameters on the irrigation performance was obtained as follows: outlet diameter, refractive surface angle, and cone hole distance. The primary and secondary order of the influence on the performance of spraying pesticide was as follows: the number of diversion chutes, angle of the outer cone of the nozzle, and nozzle diameter. The optimal combination of parameters for this water–pesticide integrated micro sprinkler was obtained as follows: outlet diameter 2.0 mm, refractive surface angle 30°, cone hole distance 1.0 d, nozzle diameter 3.0 mm, two diversion chutes, and nozzle outer cone angle 90°. The performance indices included the irrigation water flow rate 0.284 m3/h, wetted radius 4.26 m, uniformity coefficient 91.07%, flow rate of pesticides spread 0.097 m3/h, spray cone angle 121.25°, and average relative distribution span of droplets 1.18. The results provide an important theoretical basis for the practical application of sprinklers.

VALIDATION OF Σ−YLIQ ATOMIZATION MODEL IN PRESSURE SWIRL ATOMIZER

In many combustion and agricultural applications atomizers are used to increase the surface area of the liquid to ensure high rates of mixing and improve evaporation. The most common, simple, and reliable atomizer is the pressure swirl atomizer. This atomizer is said to have quality and effective atomization compared to others and induces swirling motion to the liquid and gives a hollow cone spray with air core as it emerges from the exit orifice. To enhance the understanding and prediction of the atomizing characteristics various atomization models are used and need to be investigated experimentally. This paper presents a validation of the Σ−Yliq atomization model of two-phase flow in a pressure swirl atomizer using commercial CFD star-cd code and laser-diffraction based drop measurements. To obtain the best results for the droplet mean diameter between the prediction and the experiment in terms of turbulence different k-e models were evaluated. The results show that the computational predictions of Sauter Mean Diameter (SMD) for the model have a good agreement with most of the experimental measurements in the radial positions when standard k-ɛ turbulence was used. However, more divergence was observed between the predictions and the experimental measurements when the RNG and Realizable k-ɛ turbulence models were used in the predictions. It was also observed that the model has good agreement with the mean droplet measurements on the spray centreline and radial axis with a percentage error of less than five percent.

The Influence of Droplet Distribution Coverage and Additives on the Heat Transfer Characteristics of Spray Cooling under the Influence of Different Parameters

For the objective of enhancing the heat transfer ability of spray cooling, a single-nozzle open-loop spray cooling experiment platform was established with a data measuring system. Based on the surface heat transfer coefficient obtained from the experiment, combined with the visualization system to observe the distribution of droplets during the spray cooling process, the influence of heating power, medium flow rate, nozzle height and typical additives on heating surface coverage and heat transfer characteristics were investigated. The criterion non-dimensional criteria equations for Nu, Re, Pr and size coefficients were fitted and analyzed in comparison with experimental data. The main conclusions are as follows: considering the temperature distribution characteristics of the heating surface and the shape of the spray cone, the heat transfer performance can be optimized by increasing the coverage rate under high heat flux when the flow rate changes, appropriately reducing the coverage rate under low heat flux, and appropriately reducing the coverage rate when the height changes, which creates complete coverage in the droplet concentration area to improve the surface heat transfer capacity. Furthermore, the heat transfer coefficients were improved by 29.3%, 21.8% and 23.8% with different additives (CTAB, ethanol and CTAB–ethanol mixtures) in the working fluid. Each solution had an optimal concentration and heat transfer deterioration was observed at high concentrations. When using non-dimensional criteria equations for parameter calculations, the data are more accurate after considering the effect of dimensional coefficients.

AN IMAGE PROCESSING APPROACH FOR DETERMINING THE SPRAY CONE ANGLE OF A PRESSURE SWIRL INJECTOR EQUIPPED IN A GAS-TURBINE ENGINE

This paper adopts the directionality tool provided by the ImageJ package to determine the spray cone angle of a gas-turbine engine’s injector. An imaging experiment system has been developed in this study to image a spray of a practical gas-turbine injector under injection pressure conditions varying from 2 to 6 bars. The results show that the reliability of the measurement is achieved when analyzing at least 500 images. Preferably, using 1500 images shows the uncertainty of less than 0.5% (approximately corresponding with 0.2° of the angle). The average spray cone angle varies between 100° and 128.15° when the injection pressure increases from 2 to 6 bars. An accurate determination of the spray cone angle helps to improve the quality of research on micro and macro spray characteristics including the droplet concentration and distribution. The results could also be utilized to develop a diagnostic technique for gas-turbine injectors.

CRI diesel injector transient heat–mass transfer with combustion-pollution indicated parameters consideration for Helical Orifice by various needle profiles

In the present paper, the effect of using Helical Orifice on transient heat-mass transfer and Combustion Indicated Quantities has been investigated in High Pressure Liquid Fuel Injector for different needle Movements using Avl Fire CFD code. The effect of each of the proposed needle movement profiles (triangular, trapezius, and boot) with the help of a three-dimensional moving mesh by numerical model in AVL Fire software, which has been validated with experimental data in each part, on the performance of the diesel engine and its air emission species has been investigated. Numerical results show that spiral nozzle leads to a rotational flow of fuel spray, increasing the spray cone angle and turbulence intensity inside the combustion chamber. Spiral Nozzle has more mean pressure and temperature than simple geometry of nozzle. Spiral motion leading to increasing turbulent kinetic energy and having more mean pressure, temperature, and wall heat flux. Increasing the resulting spray cone angle improves the performance of the diesel engine by reducing fuel consumption and increasing power and torque, and the production of nitrogen oxide and carbon monoxide pollutants due to a better fuel-air mixture, increased turbulence intensity and average temperature inside the chamber. fuel consumption decreases by 30% and its power and torque increase 55%. Also in this case, carbon monoxide pollutants decrease by 38% and nitrogen oxide pollutants decreasing by 30% for spiral nozzle with trapezius profile for needle movement.

A comparison between fossil and synthetic kerosene flames from the perspective of soot emissions in a swirl spray RQL burner

Swirl-stabilized turbulent spray flames operating at atmospheric pressure, with both a conventional Jet-A kerosene (‘A2’) and a synthetic fuel blend (‘C5’) and radially-injected dilution air were investigated from the perspective of soot emissions in a model Rich-Quench-Lean (RQL) combustor. The primary and downstream dilution air flow split was varied while keeping the global equivalence ratio constant (ϕg=0.4). 2.5 kHz PIV, 5 kHz OH-PLIF, and simultaneous 10 Hz Mie scattering and LII were used. Results revealed a correlation between OH and soot distributions. With no dilution air, soot volume fractions (fv) peaked in a v-shaped cone between the OH-containing regions along the spray cone and those anchored to the bluff body. With dilution air at 20% of total air flow, fv shifted to the central axis as OH distributions widened. At 40% dilution, soot initiation began farther downstream along the spray cone, OH regions merged into one, and fv peaked farther downstream at the edge of the Central Recirculation Zone (CRZ). With no air dilution, peak time-averaged fv was 20% lower in the C5 flame compared to A2, despite C5 having a higher aromatics content. However, at 20% dilution fv in C5 increased by 75% compared to the no dilution case. fv in the C5 flame dropped by 12.5% in the high dilution case compared to 40% reductions in A2. Mie scattering showed that the C5 spray was shorter and more resistant to change from dilution air compared to A2. The different spray behaviours were due to C5’s flat boiling range, lower viscosity and density, leading to higher evaporation rates. Detailed chemistry laminar flamelet simulations of A2 and C5 showed that peak soot precursor species mass fraction values and temperatures decreased as the scalar dissipation increased and a significantly stronger presence of toluene in the C5 flame compared to A2. Toluene’s soot yielding behaviour may cause C5’s increased fv with moderate dilution compared to A2. C5 demonstrates the importance of the fuel’s chemical and physical properties when developing future sustainable aviation fuels for practical applications to maximize their soot mitigation potential.

Nozzle zone agglomeration in spray dryers: Process dependency of the fines mass flow and its importance for agglomerate formation

Agglomeration in multi-stage spray dryers for food powder production is typically implemented by recycling fine material into the spray cone. The improved flow and reconstitution properties are offset by a process without direct control options. This study shows that the proportion of recycled fines allows for a more direct characterization of agglomerate formation during the process. With a measurement system based on isokinetic sampling, it was demonstrated that a total solids content of the feed solution of 30 to 50 %(w/w) resulted in a relative fines mass flow from 5.8 to 4.3 at constant process parameters. Increasing the main drying air mass flow had no effect on the relative mass flow of fines. As the fluidized bed air mass flow rate was increased, more particles were recycled, the relative mass flow rate of fines and the extent of agglomeration increased. Correlation to agglomerate size, porosity and shape confirmed that fines mass flow is a fundamental parameter for controlling and scaling agglomeration in the nozzle zone.

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.

Visualization and simulation study on impacts of wall roughness on spray characteristics of ducted fuel injection

The creative proposal of ducted fuel injection (DFI) in the application of heavy-duty diesel engines is to improve the quality of gas-fuel mixture in the combustion zone. The present research employed experimental and simulation methods to investigate the impact of the roughness of the inner wall of the duct on DFI spray characteristics. The study was carried out under injection pressure of 120 MPa and high ambient density of 54.2 kg/m3. From the perspective of spray tip penetration (STP), it was found that DFI spray configured with the smooth-walled and rough-walled duct both accelerate the axial diffusion with respect to free spray, and the smooth-walled duct performs best. Under the duct confinement, the gas entrainment does not occur inside the duct, slowing down the spray momentum decay, resulting in stronger axial diffusion after the spray penetrates through the duct. However, from the perspectives of spray cone angle (SCA) and spray area (SA), for the two duct configurations, the smooth-walled duct shows better overall diffusion compared to that of free spray, but the rough-walled duct shows weaker overall diffusion while increasing axial diffusion with respect to free spray, highlighting the strong spray-film interaction of the smooth wall promotes the overall diffusion, while the weak interaction of the rough wall accelerates the attenuation of the overall diffusion momentum with respect to free spray. Regardless of the smooth-walled or rough-walled duct, the pumping effect caused by the huge pressure difference between the inside and outside of the duct formed by the duct confinement causes strong gas entrainment at the duct inlet, promoting the strong gas-fuel mixing inside the duct, which is beneficial to the formation of leaner combustion.

Experimental investigation on spark ignition of multi-swirl spray flames under sub-atmospheric pressures and low temperatures

Altitude relight is an increasingly important issue limiting the development of low-emission combustors due to the current trend towards lean combustion. This paper experimentally investigates the flow field features and spark ignition processes inside a multi-swirl staged combustor to further reveal the internal mechanism leading to the deterioration of ignition performances under altitude conditions including sub-atmospheric pressures and low temperatures. Laser diagnostic technologies and high-speed imaging are applied to acquire the flow structures, droplet distributions, and detailed kernel motions under various inlet conditions. A flame-tracking algorithm is developed to capture the flame features (flame intensity-centroids and flame object edges) and provide the flame propagation trajectories during 10 ms following the spark. A typical “dipper-type propagation” pattern is summarized from numerous spark events and its formation mechanism can be clarified by statistical characteristics of flow and spray inside such staged combustors. The variation of ignition limits quantitatively characterizes the degree of ignition deterioration under sub-atmospheric pressures (10 ∼ 70 kPa) and low temperatures (253 ∼ 301 K). From the analysis of air to liquid ratio and Weber number, it is demonstrated that the increased droplet size and shrunken spray cone under altitude conditions are induced by three aspects, including the insufficient aerodynamic force, increased liquid viscosity force, and increased surface tension. The poor atomization quality is detrimental to the kernel generation and flame propagation and finally leads to the deterioration of ignition performances.

Effect of Fuel Injection Pressure on Spray Characterization of Mahua Biodiesel Blend Using CRDI Injection System

Abstract: In this study, the effect of fuel injection pressure on spray characterization of mahua biodiesel blend (B20) was visually analysed using CRDI fuel injection system. To analyse the spray characteristics, biodiesel blend fuel (B20) has injected at different injection pressures like 20, 30, 40and 50 MPa pressures. The fuel injection pressures and fuel injection durations were varied using electronic control module fitted with CRDI system. The spray structure of mahua biodiesel blend (B20) were recorded using a high-speed camera. For testing purpose one port of CRDI unit was connected with the solenoid fuel injector and other ports were closed. From the results obtained, it is clear that the spray tip penetration and spray cone angle were increased when the fuel injection pressure was increased from 20 to 50 MPa.

Searching for a Numerical Model for Prediction of Pressure-Swirl Atomizer Internal Flow

Numerical prediction of discharge parameters allows design of a pressure-swirl atomizer in a fast and cheap manner, yet it must provide reliable results for a wide range of geometries and operating regimes. Many authors have used different numerical setups for similar cases and often concluded opposite suggestions on numerical setup. This paper compares 2D (two-dimensional) axisymmetric, 3D (three-dimensional) periodic and full 3D numerical models used for estimation of the internal flow characteristics of a pressure-swirl atomizer. The computed results are compared with experimental data in terms of spray cone angle, discharge coefficient (CD), internal air-core dimensions, and velocity profiles. The three-component velocity was experimentally measured using a Laser Doppler Anemometry in a scaled transparent model of the atomizer. The internal air-core was visualized by a high-speed camera with backlit illumination. Tested conditions covered a wide range of the Reynolds numbers within the inlet ports, Re = 1000, 2000, 4000. The flow was treated as both steady and transient flow. The numerical solver used laminar and several turbulence models, represented by k-ε and k-ω models, Reynolds Stress model (RSM) and Large Eddy Simulation (LES). The laminar solver was capable of closely predicting the CD, air-core dimensions and velocity profiles compared with the experimental results in both 2D and 3D simulations. The LES performed similarly to the laminar solver for low Re and was slightly superior for Re = 4000. The two-equation models were sensitive to proper solving of the near wall flow and were not accurate for low Re. Surprisingly, the RSM produced the worst results.

Numerical Calculation of the Arc-Sprayed Particles’ Temperature in Transient Thermal Field

The physical and mechanical properties of the coatings produced by electric arc thermal spraying are closely related to the velocity and temperature of the particles that interact with the substrate surface. Knowing the temperature variation of the sprayed particles allows establishing their aggregation state, respectively determining the spraying distance, so that the state of aggregation of the particles at the impact moment is predominantly liquid. Obviously, when the sprayed particle passes through the spray cone, it cools continuously due to the low and variable temperature of the entrainment gas. This paper aims to determine analytically the thermal behavior of the particles entrained by the gas jet formed at the thermal spraying in an electric arc, depending on the variable temperature, existing along the spraying cone. In this sense, by modeling with finite elements, using the ANSYS program, the temperature inside the spray jet was determined, and by a mathematical model carried out based on the thermal balance equations, the thermal profile of the sprayed particles was determined. The thermal profile demonstrates that their temperature suddenly increases to the solidification temperature, then increases to the melting temperature—due to the latent heat of solidification, after which it decreases to 300 K.

Investigation on the binary ionization choices for large conjugated amines during electrospray ionization.

Generally, amines form protonated cations ([M + H]+ ) in positive polarity during electrospray ionization (ESI). However, it was found that large conjugated amines (LCAs) had binary ionization choices of generating either radical cations (M•+ ) or [M + H]+ during ESI. Investigation on the mechanism would further our understanding of ESI. In this work, the binary ionization behavior of LCAs was reported and studied. Internal factors (functional groups and sizes of conjugated systems) and external factors (solvent type, flow rate, and electrode position) were systematically investigated and discussed. For the internal factors, electron-donating groups and large conjugated structures of LCAs were conducive to the generation of M•+ . For the external factors, aprotic solvent, higher flow rate, and shorter distance from the electrode to the spray cone facilitated the formation of M•+ but hampered the generation of [M + H]+ . The present study illustrated that the formations of M•+ and [M + H]+ for LCAs were two independent processes. The M•+ cations of LCAs were formed on the surface of the electrode through electrochemical oxidation, whereas the [M + H]+ cations were generated following the typical ESI evolution process. By regulating the external factors, the ionization results of LCAs could be well modulated.

Effect of Injection Pressure on Spray Cone and Penetration Angle for Enhanced Fuel Atomization of Various Blended Viscous Fluid: A Numerical Modeling

Abstract The use of the high viscous biofuel results in poor combustion efficiency. Utilization of the biofuel on the existing engine is challenging due to the higher fuel pump force requirement and atomization effects. Hence, in this study, the spray characteristics have been examined in addition to the typical combustion and emission characteristics. In general, spray properties changes are based on the viscosity of the fuel used. Utilizing the higher viscous fluid in the engine creates havoc on liquid penetration and vapor penetration. A series of tests was conducted in the single-cylinder four-stroke diesel engine fuelled with Jatropha Curcas. The biodiesel blends were prepared at three different combinations of 10%, 20%, and 30% dispersed with the Fe2O3 nanoparticles at 50 ppm to form JF10 (10% blend + 90% diesel with 50 ppm of Fe2O3), JF20 (20% blend + 80% diesel with 50 ppm of Fe2O3), and JF30 (30% blend + 70% diesel with 50 ppm of Fe2O3). Based on the previous study observation, adding the blends affects the both combustion and performance of the engine which is counteracted in this study by adding the nanoparticles to the blends. From the obtained results, it is proved that the addition of nanoparticles increases the engine performance and emission characteristics. To be precise, the brake thermal efficiency has been improvised by 4% for the JF10 compared to neat diesel. With regard to emissions, a massive reduction in CO and NOx has been observed. To understand the quality of combustion, the fluid spray simulation has been carried out. A set of numerical simulations were done using the particle droplet analysis with the aid of star ccm+ and found that injection pressure and ambient pressure are the key responsible parameters for increasing the combustion efficiency of the system. On the other hand, the liquid length of blended fuel is another key factor that affects the atomization process. Furthermore, the high injection pressure reduces the spray cone angle for biodiesel by achieving high mixing rates.

Fouling mechanism in airblast atomizers and its suppression for water desalination

A detailed experimental study is presented on fouling behavior of the anti-clogging perforated plate atomizer designed for high salinity applications, and compared with a conventional (plain-jet) airblast atomizer. Low-pressure regions around fast moving air in the outer layer of spray (as in conventional atomizers: plain-jet and prefilming) due to Venturi suction were identified as the root cause of atomizer clogging, as they facilitate salt accumulation on the atomizer surface from spray. Accordingly, severe atomizer fouling, and fluctuations in spray cone angle were observed in the conventional airblast atomizer over 2 h at 100°C air and 50°C saline (44° to 76° at 35,000 ppm, and 44° to 91° at 100,000 ppm). In this regard, the perforated plate atomizer provides a novel liquid-film airblast atomization by maintaining a liquid-annulus film (around the air outlet) as the outer layer of spray. Doing so we achieved nearly complete suppression of fouling, and spray cone angle fluctuations (28° ± 1° at 35,000 ppm, and 30° ± 1° at 100,000 ppm). Later, novel liquid-film atomization was adopted in the conventional airblast atomizer. While, the conventional airblast atomization needed atomizer cleaning/maintenance after 35 min for 175°C air and 65°C saline at 100,000 ppm, the liquid-film atomization showed no sign of fouling over 14 h. Hence, current work establishes a benchmark liquid-film airblast atomization mechanism in the anti-clogging perforated plate atomizer for complete suppression of fouling in airblast atomization. This extends the application of airblast atomizers from high evaporation jet engines to ZLD-HDH desalination systems, spraying, powder metallurgy, pharmaceuticals and hospitals, and spray drying and cooling.