Spray Angle Research Articles

Development of an IOT based Solenoid Controlled Pressure Regulation System for Precision Sprayer

Abstract: In recent years, Precision Agriculture has embarked a promising role in augmenting agricultural production and various farm mechanization. The present research was conducted to design and develop a Precision Spraying System (PSS) that is controlled by an Automatic Control System (ACS). PSS was equipped with micro-controller (NodeMCU), an analog pressure regulator, solenoid valve, diaphragm pump coupled with 12V DC motor; operated on a Iot platform BLYNK. A 3D printed full cone nozzle (0.2 mm orifice dia., cone angle of 95°) was designed to achieve desired spraying efficacy as per the canopy area and the need of the crop cultivated. Integration of PSS with ACS, intrigues a proper regulation on the valves (24V, 7.92W), the pump speed, pressure head and flow rates. The spray patternator test was conducted to evaluate the Delay Time Losses (DTL), application losses, effective spraying height and pressure. The test was conducted for 4 sets of increasing pressure (5.46, 6.24, 6.86 and 7.80 bar) and 3 sets of decreasing nozzle heights (890, 760 and 620 mm). The results revealed that the maximum average discharge collected from the Patternator tray was 0.45L/min (at pressure 7.80 bar; height 620 mm) and the minimum average discharge collected was 0.26 L/min (at pressure 5.46 bar; height 890 mm). The spray angle was found to vary from 72 to 82° and the percent (%) loss in discharge was estimated to maximum of 49.02% (at height 890 mm) and the minimum value of 11.76% (at height of 620 mm) suggesting possible wind drift with increasing nozzle height. Thus, the designed PSS is propitious to forefend all the ill effects of conventional spraying and it significantly reduces the DTL to 0.5 sec

TEORETICAL-EXPERIMENTAL COMPARISON OF THE MODELS OF ADDITIVELY MANUFACTURED SWIRL INJECTORS BASED ON THE HYDRAULIC TESTING RESULTS

Annotation. Recent success in development of the technology stipulated the appearance of advanced additive manufacturing aimed to shift conventional subtractive manufacturing from its position in the engineering field. Thus, for LPRE manufacturing there is an obvious advantage of additive manufacturing in terms of ability to produce single-piece parts with complex geometry must be seriously considered. In the modern world there is a constant competition between complex engineering decisions and cost efficiency of the production on the market of liquid propellant rocket engines. On the one hand, mixing head is one of the most demanding parts of LPRE in terms of designing. On the other hand, the earliest stage of its development starts with the choice of a type of mixing elements to ensure combustion stability, efficiency, and overall production cost [1]. Typically this step requires advanced knowledge in the real characteristics of produced injectors, or extensive experimental study should be carried out otherwise. In this work a problem of determining the characteristics of additively manufactured swirl injectors is considered. Laser Powder Bed Fusion [10] was chosen as a production method using Haynes 230 as a main material. A range of the swirl injectors with varied geometrical parameters was manufactured. Hydraulic testing was carried out in a wide range of Reynolds numbers for determining flow characteristics. Typically, discharge coefficient and spray angle are the desired values to know. Sauter mean diameter and film thickness were not studied due to lack of equipment. Considering a problem of prediction of the main characteristics of the produced injectors, a review on known equations for calculation of the main parameters was performed. Comparative analysis between calculated and experimental data was carried out. Results show that there is severe discrepancy between calculated values of characteristics of injectors and experimentally obtained data for additively manufactured swirl injectors. Even though the conducted study gives a base to form consistent conclusions of the behavior of the obtained characteristics, additional investigation is required.

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

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

Experimental and Numerical Study of Al2219 Powders Deposition on Al2219-T6 Substrate by Cold Spray: Effects of Spray Angle, Traverse Speed, and Standoff Distance.

Cold spray (CS) is an emerging technology for repairing and 3D additive manufacturing of a variety of metallic components using deformable metal powders. In CS deposition, gas type, gas pressure, gas temperature, and powder feed rate are the four key process parameters that have been intensively studied. Spray angle, spray gun traverse speed, and standoff distance (SoD) are the other three process parameters that have been less investigated but are also important, especially when depositing on uneven substrates or building up 3D freeform structures. Herein, the effects of spray angle, traverse speed, and SoD during CS deposition have been investigated holistically on a single material system (i.e., Al2219 powders on Al2219-T6 substrate). The coatings' mass gain, thickness, porosity, and residual stress have been characterized, and the results show that spray angle and traverse speed exercise much more effects than SoD in determining coatings' buildup. Finite element method (FEM) modeling and computational fluid dynamic (CFD) simulation have been carried out to understand the effects of these three parameters for implementing CS as repairing and additive manufacturing using aluminum-based alloy powders.

Study of the Variation of Fuel Pressure to Improve Spraying and the Range of the Injection Jet

The current study is focused on how varying injection pressure in the fuel supply system of multi-point injection systems can improve fuel atomization and injection jet range. The aim is to achieve a more efficient mix dosage, thus improving combustion and reducing exhaust emissions. In addition, it is intended to develop a characterization of the injection actuators, specifically the injectors, through a series of tests in which the injector pressure, engine speed and injection pulse are modified. To carry out these tests, a heuristic testing technique, like the empirical approach, was implemented, and a mobile device was used to capture the spray frames of the injectors. These data were then used to generate a correlation model between injection and spray angles, considering 0.5 bar pressure variation intervals within the established ranges. This approach made it possible to visualize and record the behavior of the spray in the injector, including the spray angle, the injected fuel flow rate and the working pressure during the operation process. Following the guidelines established in the proposed methodology, a significant result was obtained by varying the pressure at 5 bar and with an injection pulse of 2 ms. In this case, a flow reduction of 66 mL of the injected fluid was achieved, which corresponds to a significant reduction in fuel consumption. Additionally, a spray angle of 10.48° was observed with optimized atomization. These results were verified on vehicles with similar injection systems by testing on the GT-600-PRO injection test bench. In summary, this study shows that by varying the injection pressure and optimizing other parameters, it is possible to achieve a significant reduction in fuel consumption and improve fuel atomization in multipoint injection systems. These findings have a significant impact on the Ecuadorian vehicle fleet and provide a scientific approach to improving fuel efficiency and performance.

Energy‐saving glass‐melting‐furnace with semi‐dry plasma‐chemical hybrid process

AbstractA low‐cost plasma‐chemical hybrid process (PCHP) is proposed for simultaneous NOx and SOx treatment. PCHP can be integrated into existing desulfurization reactors by combining plasma oxidation and chemical reduction. PCHP is applied to glass melting furnace emissions with limited denitration technology, achieving higher removal efficiencies of NO, NOx, and SO2 (43%, 38%, and 28%, respectively) by optimizing reductant spray and installation angles. PCHP also improves fuel consumption, with a 0.04 increase in air ratio reducing energy consumption by 3.6 kL/day (equivalent to 6.6 t(CO2)/day reduction). In addition, PCHP allows for the collection and reuse of treated SO2 as sodium sulfate particles, making it a suitable aftertreatment technology for glass manufacturing exhaust.

Twin injector biogas diesel RCCI mode-an effective means to reduce NOx emissions without penalty in fuel consumption

The RCCI (Reactivity Controlled Charge Compression Ignition) mode of operation of an IC engine using biogas and diesel as fuels has the potential to offer high efficiencies and low NOx and soot emissions. One of the drawbacks while converting conventional diesel engines to run in this mode is the wall wetting of the diesel that has to be injected early in the compression stroke. This leads to high THC emissions and lubricating oil dilution. In this work a twin cylinder turbocharged, common rail diesel engine was modified to accommodate a newly developed Narrow angle Injector (NI) for early injection of diesel without wall wetting, along with the existing Wide angle Injector (WI). Biogas was also injected into the intake manifold and the engine was run in the RCCI mode. The effectiveness of this novel twin injector dual fuel RCCI concept has been experimentally assessed at different biogas energy shares under a BMEP of 3 bar and at a constant engine speed of 1500 rpm. The different biogas – diesel modes considered were the conventional dual fuel mode (CDF), RCCI with the WI alone, RCCI with the NI alone and finally RCCI with the combined NI-WI. In the biogas diesel RCCI mode the use of only the WI resulted in low efficiency, high THC and smoke emissions due to cylinder wall wetting of diesel. Though the use of only NI in this mode could eliminate cylinder wall wetting, the diesel directly hitting the piston bowl resulted in poor performance. However, the combination of NI and WI resulted in high BTE and extremely low levels of NOx emissions and lower THC as compared to the CDF mode. The range of injection timings for the NI was 90° to 45° bTDC while for the WI it was 42° to 4° bTDC when the energy share of biogas was changed. Thus the use of two injectors with wide and narrow injection spray angles for diesel gave enhanced flexibility in operating at widely different injection timings as required in biogas diesel RCCI operation.

Study on duplex air-blast atomizers spray in the engine real operation conditions

Air-blast atomizers are widely used in passenger aircraft engines. In these atomizers, high-speed airflow is used for improved fuel atomization, and as a result, better combustion. The key purpose of this research is to investigate the duplex air-blast atomizers according to the engine data in the real operational conditions with the help of experimental method and numerical solution. When analyzing the variations in fuel sprays under different application conditions, it is important to consider not just one but multiple parameters such as fuel mass rate, air mass rate, and combustion chamber pressure. However, analyzing the individual effects of these parameters can be challenging as they change simultaneously. To address this, a dimensionless number namely K was defined, which takes into account the combined effect of fuel mass rate, air mass rate, and combustion chamber pressure. The results showed that when K decreased by 31.25%, the spray angle of nozzle 1 and nozzle 2 increased by 10.09% and 48.15%, respectively, while the average droplet diameter caused by primary breakup for nozzle 1 and nozzle 2 decreased by 76.29% and 71.57%, respectively. The secondary breakup was somewhat similar, and for nozzle 1 and nozzle 2, the average droplet diameter decreased by 76.5% and 71.88%, respectively. It is worth noting that the average error for spray cone angle in the simulation compared to the experimental results was 6.47%. The results of this research, in addition to causing a better understanding of the atomization processes in air-blast atomizers, can be useful for aerospace engineers.

Effect of Density and Viscosity on Injection Characteristic of Jatropha - waste Cooking Oil Biodiesel Mixture.

Biodiesel has an important role in the world of transportation and its existence is taken into account. So the availability of biodiesel fuel in the future will be difficult to eliminate and must continue to be fulfilled. Therefore, it is necessary to innovate to increase the availability of biodiesel fuel. Biodiesel can be made from biological materials and includes renewable energy as a substitute for diesel oil. The production of biodiesel in this study jatropha and waste cooking oil as raw materials. This study aims to determine the effect of density and viscosity on the injection characteristics of jatropha-waste cooking oil biodiesel mixtures (1:4 and 4:1) on various B5-B40 fuels. Production of biodiesel from jatropha and waste cooking oil through degumming, esterification and transesterification processes. The results showed that the jatropha-waste cooking oil biodiesel mixed with 1:4 level B15 and 4:1 mixed with B10 level complied with SNI 7182-2015 biodiesel standards. The higher the density and viscosity values of jatropha-waste cooking oil biodiesel, the narrower the spray angle and the longer the spray penetration

Metrological relations between the spray atomization parameters of a cutting fluid and formation of a surface topography and cutting force

Aerosol formation parameters are very important, as they are responsible for the ability of spray-forming droplets to penetrate the area to which they are applied. Research into modifying these parameters can therefore provide a solution for increasing the effectiveness of cooling and lubrication of the cutting zone during machining. This is particularly important for hard-to-cut materials such as titanium alloys, the machining of which requires the selection of effective cooling/lubricating methods to reduce tool wear or improve the machined surface quality. Previous research indicates that any modification in the air or oil flow rates – which form aerosols during cutting in minimized quantity lubrication (MQL) technique – contribute to an increase or decrease in the penetration of droplets into the cutting zone. It can consequently has a significant impact on machining results. This paper presents results on the effect of volumetric air flow rate P and cutting fluid mass flow rate E during the MQL cutting method on the machined surface topography after turning of Ti6Al4V alloy and the values of the cutting force. On the basis of conducted computational fluid dynamics (CFD) simulation studies, it was shown that the droplet size is more influenced by the change in volumetric air flow rate than cutting fluid mass flow rate and also that as the value of P increases, the droplet diameters decrease and the spray angle increases, which promotes the penetration of the cutting zone. As a result of the analysis of selected 3D surface roughness parameters, as well as contour maps, isometric views and material ratio curves, it was shown that the most favorable machined surface topography is being formed during MQL turning method with a volumetric air flow rate above 20 l/min. Whereby, with conditions of P = 30 l/min and E = 1.182 g/min, the machined surface topography is characterized by a uniform distribution of irregularity peaks and valleys, compared to the MQL turning with other tested values of aerosol formation parameters.

Simulations of ammonia spray evaporation, cooling, mixture formation and combustion in a direct injection compression ignition engine

This study investigates the novel approach of direct liquid ammonia injection into the combustion chamber of a compression ignition engine. Unlike traditional gaseous ammonia port injection, this method shows promise in reducing ammonia slip and emissions. To simulate and analyze the behavior of the liquid ammonia spray, we employed numerical models based on existing literature on flashing and non-flashing spray simulations, as well as recent experimental studies on ammonia spray characteristics using a gasoline direct injection (GDI) injector. Our approach utilized a Lagrangian discrete phase modelling technique to perform a series of three-dimensional computational fluid dynamics (CFD) simulations. The primary objectives of this research were to evaluate the evaporation process of ammonia and its cooling effect, as well as to gain insights into mixture formation within the engine cylinder under different operating conditions. The simulations encompassed the entire engine cycle, considering a multi-hole GDI ammonia spray in conjunction with pilot n-heptane, a diesel surrogate, in equal proportions on an energy basis. Three distinct injection timings for ammonia were examined, leading to varying thermodynamic conditions within the combustion chamber during each spray formation. Consequently, different modelling parameters and initial conditions were necessary to accurately replicate the spray behavior. To address this, we proposed a systematic procedure for assigning pre-defined spray angles. The non-reacting, evaporating spray simulations yielded valuable insights into the mixture formation process, which guided our analysis. Finally, reacting conditions were considered to evaluate engine performance and resulting exhaust gas emissions. This study provides a comprehensive overview of critical aspects related to direct ammonia injection in internal combustion engine (ICE) systems. Moreover, it uncovers performance trends that can serve as a foundation for future investigations in this field.

Evaluation of the Parameters of the Dispersed Stream Generated by Various Types of Water Nozzles

Aim: The purpose of the research was to determine the parameters of the micro- and macro-structure of the streams generated by nozzles of different types, and to identify potential applications of the tested water nozzles, including firefighting and air pollution removal. Introduction: TF6 FCN, TF6 V, NF 15 and CW 50 water nozzles were tested. At supply pressures of 0.2 MPa, 0.4 MPa and 0.6 MPa, the basic parameters of micro- and macrostructure of the streams were measured and determined: flow rate, spray angle, mass distribution of liquid on the surface (spray intensity), non-uniformity of spray density distribution, and average droplet diameters and spray spectrum. A sputter spectrum analyser, using the photoelectric method, was used to determine the microstructural parameters of the stream. Project and methods: Badaniom poddano dysze wodne TF6 FCN, TF6 V, NF 15 oraz CW 50. Przy ciśnieniu zasilania równym 0,2 MPa, 0,4 MPa oraz 0,6 MPa zmierzono i wyznaczono podstawowe parametry mikro- i makrostruktury strumieni: natężenie przepływu, kąt rozpylenia, rozkład masowy cieczy na powierzchni (intensywność zraszania), nierównomierność rozkładu gęstości zraszania oraz średnie średnice kropel i widmo rozpylenia. Do określenia paramentów mikrostrukturalnych strumienia zastosowano analizator widma rozpylenia, wykorzystujący metodę fotoelektryczną. Results: The tested nozzles generated dispersed streams with different parameters. Among the analysed nozzles, the highest degree of dispersion was obtained for the TF 6 FCN sample, whose average Sauter mean diameter (SMD) reached a value of 217.3 μm. In comparison, for the NF15 nozzle this parameter was 945 μm. The spray spectra indicate a high homogeneity of water dispersion in the stream produced by the nozzles TF 6 FCN and CW 50. From the distribution of mass sprinkling density, the CW 50 nozzle shows the greatest uniformity of spraying. At the same time, however, it reports a small amount of water, since the value of the spray density for this product did not exceed 100 g/( m2 · s), while for the NF 15 nozzle it was more than 2,700 g/( m2 · s). The obtained spray angles were close to those declared by the nozzle manufacturer. In the tests of all samples, a slight effect of supply pressure on the values of this parameter was observed. Conclusions: Among other things, the tests made it possible to conclude that in the range of supply pressures of 0.2÷0.6 MPa, the values of disperse angle and spray area of the analysed nozzles were constant or the recorded differences were insignificant. In addition, it was determined that in the case of nozzles with full spray cones, an increase in supply pressure (within the range of declared operating values) has little effect on changing the parameters of the micro- and macro-structure of the stream. The conducted tests showed the potential use of two nozzles (TF6 FCN, CW 50) in low-pressure fog extinguishing systems producing fog with SMD droplet diameters > 200 μm. For the absorption of hazardous substances, it is recommended to use nozzles with a large spray angle and a full spray cone, which, as tests have shown, produce uniform streams with small droplet diameters. Keywords: water nozzles, water spray, spray spectrum, mass spray density, water mist

A Numerical Approach to Optimize the Design of a Pintle Injector for LOX/GCH4 Liquid-Propellant Rocket Engine

This study presents an optimal design approach of a pintle injector for a deep throttlable liquid-propellant rocket engine (LPRE). Even though the pintle injector is used in rocket engines, it has become more important since reusable launch vehicles (RLVs) recently became a trend due to their economic and environmental benefits. However, since many variables must be determined to design a pintle injector, optimizing the pintle injector design is complicated. For this, we design a pintle injector to optimize the performance parameters; the spray angle, vaporization distance, and Sauter mean diameter (SMD). To confirm the approach, we design a pintle injector using an optimization method based on convex quadratic programming (CQP) for a 1000 N thrust and a throttle ability of 5 to 1 LPRE with liquid oxygen and gaseous methane. Then, we verify the performance using a numerical simulation. Through this work, we check the effectiveness of the optimization method for a pintle injector design.

CFD analysis of the spray droplet parameters effect on gas-droplet flow and evaporation characteristics in circulating fluidized bed desulfurization tower

The circulating fluidized bed flue gas desulfurization (CFB-FGD) process is a promising semi-dry flue gas desulfurization technology. The gas-droplet flow characteristics and droplets evaporation characteristics are critical to improving the desulfurization efficiency of the FGD tower. The effects of droplet parameters, including spray droplet diameter, spray droplet velocity, spray droplet mass flow rate and spray angle are investigated. Two evaluation indices, the coefficient of variation of droplet concentration (CV) and droplet mass-weighted life, are adopted to evaluate mixing degree of gas-droplet and droplet evaporation time, respectively. Results show that as the spray droplet diameter increases from 40 µm to 80 µm, the amount of water droplets trapped by tower wall increases from 3% to 21%. Increasing the spray droplet velocity and spray droplet mass flow rate could effectively increase the turbulent kinetic energy, which could improve the turbulent mixing ability. Moreover, droplet with smaller diameter and high velocity are beneficial to improving the temperature distribution uniformity. When the spray droplet mass flow rate exceeds 2.7 kg/s, the temperature in the tower would be lower than the dew point temperature, resulting in corrosion of the tower wall. Furthermore, the evaporation rate of droplets decreases with the increase of droplet diameter, spray droplet velocity and spray mass flow rate, while increases with the increase in the spray angle. This study would provide a better reference for the optimum operating scheme in practical applications.

Visualization of nasal powder distribution using biomimetic human nasal cavity model

Nasal drug delivery efficiency is highly dependent on the position in which the drug is deposited in the nasal cavity. However, no reliable method is currently available to assess its impact on delivery performance. In this study, a biomimetic nasal model based on three-dimensional (3D) reconstruction and three-dimensional printing (3DP) technology was developed for visualizing the deposition of drug powders in the nasal cavity. The results showed significant differences in cavity area and volume and powder distribution in the anterior part of the biomimetic nasal model of Chinese males and females. The nasal cavity model was modified with dimethicone and validated to be suitable for the deposition test. The experimental device produced the most satisfactory results with five spray times. Furthermore, particle sizes and spray angles were found to significantly affect the experimental device's performance and alter drug distribution, respectively. Additionally, mometasone furoate (MF) nasal spray (NS) distribution patterns were investigated in a goat nasal cavity model and three male goat noses, confirming the in vitro and in vivo correlation. In conclusion, the developed human nasal structure biomimetic device has the potential to be a valuable tool for assessing nasal drug delivery system deposition and distribution.

Simulation of parameters effects on fluid flow behavior in the spraying nozzle: A case study of greenhouse cultivation

The study aims to investigate the effect of nozzle diameter size and pressure on the angle and flow rate of the spray nozzle in greenhouse cultivation. The misting system is a new method that is used to provide humidity and reduce the temperature of the greenhouse environment. The study used a factorial experiment in a randomized completely block design (RCBD) to investigate and compare the effect of pressure at three levels of 20, 40, and 60 bar on three types of fog sprayers (nozzle type of 0.05, 0.04, and 0.03) on the quality of spray pattern and particle distribution. The results of the analysis of variance showed that the treatments of spray type, pressure, and interaction of both treatments had a significant difference at the level of 1%. The highest spray angle of 84.93° is related to the pressure of 60 bar, and the lowest spray angle of 71.27° is related to the pressure of 20 bar. The pressure was directly related to the spray angle, and increasing the pressure increased the spray angle in the nozzle. The study also found that the best pressure in the new nozzle for the frequency distribution contour is 40 bar, and the new nozzle contours show that this type of nozzle has increased the uniformity of spraying. Overall, the findings suggest that controlling humidity and temperature in the greenhouse through the use of misting systems and optimized nozzle design can improve the speed and uniformity of plant growth and increase the quality and quantity of plant production in greenhouse cultivation.

Experimental investigation on heat transfer performance during electrospray cooling with ethanol–R141b mixture

Electrospray (ES) cooling is promising to achieve energy-efficient liquid atomization and high-heat-flux thermal dissipation at relatively low operating temperatures (<75 °C) when using an ethanol–R141b mixture as a coolant, making it suitable for micro-sized electronics. Nevertheless, there has been little research on ES cooling using the ethanol–R141b mixture. This paper presents an experimental investigation on the cooling performance triggered by ES impingement. Results demonstrate that adding ethanol to R141b improves the electrohydrodynamic (EHD) atomization, namely reducing Sauter mean diameter and increasing spray angle. Meanwhile, it also causes the deposition of large-size isolated liquid films on the surface. As the mass concentration of ethanol increases from 10% to 60%, the cooling performance in terms of the temperature drop (Ts,d) and time-averaged heat transfer coefficient (hm), first increases and then decreases or almost remains unchanged. This is a complicated consequence of microscopic droplet behaviors, film deposition, and thermal properties, which are dependent on the mass concentration of ethanol. For volumetric flow rates of 100 and 150 mL/h, the ES sprays with mass fractions of 50% and 20% produce preferable cooling capabilities with respective hm equivalent to 1.6 and 1.9 kW/(m2·K) under the current tests. A Nusselt number correlation with the electric Weber, hydrodynamic Weber, and Prandtl numbers is derived. This correlation covers more than 97.7% of the experimental data within a ± 15% deviation. The derived correlation implies the increase in the flow rate has a superior contribution to the heat transfer in comparison with the applied voltage.

Investigation of Microstructural Characterization and Mechanical Properties of 8YSZ Thermal Barrier Coatings: Atmospheric Plasma Spray versus Electron Beam-Physical Vapour Deposition

In this study, the formation and growth of coating microstructure was studied and reported based on APS and EB-PVD deposition mechanism with the change in spray angle. A NiCrAlY bond coat with 8YSZ ceramic coat was applied by APS and EB-PVD deposition onto the Inconel 718 with the variation in spray angle. The investigation was divided into microstructural analysis and mechanical properties to determine the effect of different deposition mechanism and its variation in spray angle. The results obtained show that the APS with 60° spray angle has more presence of defects, followed by APS 90° and EB-PVD samples. The APS avg. grain size varies between ~ 400 to 800nm, whereas EB-PVD in between ~ 150 to 300nm. The EB-PVD with 90° spray angle results in low porosity i.e. 18.12 % followed by APS 90°, EB-PVD 60°, and APS 60° spray angle, respectively. The low porosity results in high compressive residual stress than medium and high porosity. The avg. Raman shift for EB-PVD 90° spray angle i.e. low porosity is 1.86 cm-1, for medium i.e. APS 90° and EB-PVD 60° is 1.33cm-1 and 1.53cm-1 respectively, and for high porosity is 0.93cm-1. The 90° spray angle showed better microstructural and mechanical properties compared to 60°.

Numerical study on the effects of blocking ratio and spraying angle on the smoke flow characteristics of new energy vehicle fires in tunnels

Compared with traditional fuel vehicle fires, new electric vehicle fires have a fast flame propagation rate and higher smoke toxicity. Thus, higher requirements need to be implemented when designing tunnel fire protection. In this study, a horizontal highway tunnel with a rectangular cross-section is taken as the research scenario, and the FDS numerical simulation method is used to study the effects of different blocking ratios and key parameters of the water mist system in a rectangular tunnel under longitudinal ventilation on the smoke temperature and flow state near the fire source area. The results indicate that the average velocity of smoke in the vicinity of the fire source in the tunnel is mainly related to the cross-sectional size of the obstruction, and changing the spray angle does not affect the state of the smoke flow field. The relationship between the cross-sectional size of the blocked vehicles in the tunnel and the spray angle is proposed. In addition, when the blocking ratio reaches 25%, the back-layer length of smoke corresponding to the subsequent blocking ratio remains basically unchanged. Setting a reasonable spray angle can significantly reduce the CO mass fraction in the tunnel, while the visibility of the tunnel will also decrease. Using the dimensionless analysis method, a critical velocity correction model based on the blocking ratio factors is proposed. These research results provide a theoretical reference for the design of longitudinal ventilation and smoke exhaust for new energy-electric vehicles in highway tunnels.

A Simulation of Artificial Neutral Gas‐Dust Plasma in the Ionosphere

AbstractDusty plasma is generally defined as a plasma system containing a large number of nano‐ or micron‐sized dust particles. Its plasma properties and propagation properties of wave travel through it is of great scientific significance to the understanding of many fundamental problems in space physics and astrophysics. Based on previous studies on rocket exhaust and Polar Mesosphere Summer Echoes, fluid mechanics and dust microphysics are combined to simulate the ionospheric plasma structure generated by neutral gases and charged aerosols using fluid theory and kinetic theory. The Total Electron Content of the in‐situ detection beacon is simulated and compared with the experimental phenomenon given in Charged Aerosol Release Experiment by Bernhardt et al. The ray tracing algorithm is used to simulate the path deflection of the radio wave when it passes through the artificial disturbance area generated by the gas‐solid mixture, and the simulation results of ionosonde and analysis are given. Since the neutral gas expands substantially isotropically after being released, the resulting depleted structure is an approximately isotropic sphere, or an acorn‐like structure. The solid particles are constrained by the nozzle, and particles will distribute within a spray angle, and the depletion structure will appear as a “broom‐like” or “cone‐like” structure. If the size of dust particles is small enough, the particle movement will be restricted by the geomagnetic field, resulting in a “squid‐like” ionospheric structure. Because of the fishtail‐like sharp boundary, radio waves passing through it are deflected in a specific path, which is markedly different from the effect of pure neutral gas injected into the ionosphere.