Jet Mixing Research Articles

Effect of temperature, geometric parameters, and surface conditions on fluid mixing in a vertical port static mixer

This study comprehensively investigates how elevated temperature and surface roughness affect vertical liquid jet mixing in a multi-port nozzle, using both experimental and computational methods. It explores various geometrical parameters and precise nozzle positioning. Experiments, conducted across different temperature and surface roughness conditions, involve adjusting convergent nozzle angles, driving nozzle distance from the throat, and insert presence. Conductivity probes, turbidity meters, and pH meters quantify fluid mixing under diverse conditions. Optimal mixing conditions for vertical flow secondary fluid inlets are determined, along with corresponding mixing efficiencies for each port. Computational fluid dynamics (CFD) simulations with ANSYS Fluent R2 2001 confirm that the highest mixing efficiency of nearly 98% is achieved with an elevated temperature of 50 °C, a rough-surfaced convergent nozzle, a helical insert, and a 45 mm driving nozzle distance, when all vertical ports are open simultaneously. These findings advance understanding of optimizing vertical-flow mixing in multi-port static mixers under varying conditions.

Insights into the hydrodynamics in the annular pipe of industrial‐scale top‐blown smelting furnace

AbstractThe coaxial jet consisting of swirl jet and axial jet plays a critical role in the industrial processes but is rarely investigated; therefore, it is numerically explored by means of the computational fluid dynamics (CFD) approach in the present work. The force on the swirler, axial and tangential velocity at the annular pipe outlet, and the spatial distribution of swirl number (SN) are selected to evaluate the effect of geometrical parameters on the swirling performance. The results clarify that the velocity and their azimuthal components in the transverse cross‐section can be categorized into six segments based on high/low velocity values. The coaxial jets form a weak swirl with high axial, certain tangential, and low radial velocities. x‐ and y‐vorticity vary within −200 to 200 s−1. Coaxial jet mixing decays the SN. Based on the multi‐objective matrix analysis, swirler height has the largest effect on swirl performance followed by diameter, angle, and number based on analysis. Optimal parameters are 130° vane angle, 240 mm diameter, 10 vanes, and 250 mm height of the swirler.

The effect of comb length on the in vitro and in vivo properties of self-assembled poly(oligoethylene glycol methacrylate)-based block copolymer nanoparticles.

Comb copolymer analogues of poly(lactic acid)-polyethylene glycol block copolymers (PLA-b-PEG) offer potential to overcome the inherent chemistry and stability limitations of their linear block copolymer counterparts. Herein, we examine the differences between P(L)LA10K-b-PEG10K and linear-comb copolymer analogues thereof in which the linear PEG block is replaced by poly(oligo(ethylene glycol) methacrylate) (POEGMA) blocks with different side chain (comb) lengths but the same overall molecular weight. P(L)LA10K-b-POEGMA47510K and P(L)LA10K-b-POEGMA200010K block copolymers were synthesized via activators regenerated by electron transfer atom transfer radical polymerization (ARGET ATRP) and fabricated into self-assembled nanoparticles using flash nanoprecipitation via confined impinging jet mixing. Linear-comb copolymer analogues based on PLA-b-POEGMA yielded smaller but still well-controlled nanoparticle sizes (88 ± 2 nm and 114 ± 1 nm respectively compared to 159 ± 2 nm for P(L)LA10K-b-PEG10K nanoparticles) that exhibited improved colloidal stability relative to linear copolymer-based nanoparticles over a 15 day incubation period while maintaining comparably high cytocompatibility, although the comb copolymer analogues had somewhat lower loading capacity for doxorubicin hydrochloride. Cell spheroid studies showed that the linear-comb copolymers promoted enhanced tumor transport and thus cell killing compared to conventional linear block copolymers. In vivo studies showed all NP types could passively accumulate within implanted CT26 tumors but with different accumulation profiles, with P(L)LA10K-b-POEGMA200010K NPs showing continuous accumulation throughout the full 24 h monitoring period whereas tumor accumulation of P(L)LA10K-b-POEGMA47510K NPs was significant only between 8 h and 24 h. Overall, the linear-comb copolymer analogues exhibited superior stability, biodistribution, spheroid penetration, and inherent tunability over linear NP counterparts.

Experimental study on droplet breakup in an orifice jet mixer

AbstractThe droplet breakups in an orifice jet mixer are studied to gain a deeper understanding of the breakup mechanism and establish breakup models used as population balance model source terms for accurate predictions. The breakup process and details are captured in situ using a high‐speed photomicrography system. Experiments are performed with different levels of pressure drop and mother droplet size. A complete breakup process consists of several different sub‐breakup events, hence the cascade breakup definition is adopted to determine statistical results. High breakup frequency is achieved under high pressure drop and small mother droplet size. The average number of daughter droplets is 102–105 and is positively correlated with the pressure drop and mother droplet size. The daughter droplet size distribution has a tailing phenomenon and is mainly affected by the pressure drop. New breakup models based on the above features are established and predict well with the experimental results.

Computational Study on the Effect of Vane Design in Enhancing the Mixing of Subsonic Jet and Sonic Jet

The purpose of this study is to numerically analyze the effect of vortex generators that are shaped like vanes in enhancing the mixing of subsonic and sonic jet and to determine the best design which yields maximum reduction in jet potential core length and minimum thrust loss at the nozzle exit. Four different nozzle designs namely, models A, B, C and D are designed and compared with a base nozzle which is a plain circular nozzle without any vanes. The simulation is performed in ANSYS Fluent using the S-A turbulence model. The centerline pressure decay and radial pressure decay from models A to D are compared with that of the base nozzle to determine the ability of the vane to enhance the jet mixing characteristics. To evaluate the thrust loss, the total pressure at the exit plane of models A to D is measured and compared with that of the base nozzle. When comparing all the designs, it is observed that Model B produces the highest reduction in potential core length which is 66.4% at Mach no. 1 and Model D produces minimum total pressure loss which is 0.47% at Mach no. 0.4. In contrast to the conventional method, this design introduces a novel approach by placing the vanes parallel to the flow instead of the usual perpendicular arrangement. This unique configuration allows the vanes to redirect the flow rather than hinder it, resulting in a total pressure loss of less than 3%.

A numerical investigation into thermo-fluid characteristics of pulsating jet impingement on a dimpled surface

A two-dimensional axisymmetric numerical model is employed to study the flow and heat transfer attributes of the pulsating air jet impingement on a dimpled surface. The results are compared with the steady jet impingement. The results are examined at a fixed Reynolds number of 5000, over a Strouhal number range of 0.1–0.5, and pulsation amplitude of 15% and 25% for three different nozzle-to-surface separations (z/d = 2, 6, and 10). The pulsation amplitude of 15% has a minor effect on heat transfer from the dimpled surface. However, at 25% pulsation amplitude, significant improvements in the heat transfer rates are obtained in many combinations of jet Strouhal number and jet surface spacing. The value of the optimum Strouhal number provides conditions for the maximum heat transfer rate, which varied with nozzle-to-surface separation distances. Combinations of higher separations and lower Strouhal numbers (and vice versa) produced optimum heat transfer among the cases considered in the present study. The maximum improvement (17.41%) in the average heat transfer over the steady jet was found at z/d = 10 for pulsation at St = 0.1, while at z/d = 6, St = 0.2 provides the highest heat transfer rate. It is urged that the vortices formed in pulse jet close to the natural frequency of vortex formation provide a conducive environment for the vortex growth and their existence, significantly affecting the jet entrainment, mixing, and jet spread, which eventually play the decisive factor in determining the overall heat transfer rates on the dimpled surface.

Simulation of supersonic jet flow past a blunt body in a laboratory experiment using computer vision

The complex flow of a supersonic jet (Mach number 2.4–2.5) around the blunt aerodynamic body (consisting of a cylinder with a diameter of 16 mm and a truncated cone) was studied using the high-speed shadowgraph technique and computer vision-based visual data processing. The problem considered is directly related to the rocket and space systems stages safe separation problem in a sufficiently dense atmosphere. For systems with a sequential arrangement of stages, their separation often occurs under the rocket engine jet action. The occurrence of lateral forces in violation of axial symmetry can lead to overturning of the discarded stage and undesirable interaction with the outgoing stage. The goals of the paper were to study the pulsation characteristics of the incoming supersonic jet streamlining the body, as well as the pulsations of the bow shock wave in both axisymmetric and asymmetric flows. The recording frame rate in the experiments was up to 775 000 fps. Computer vision and various machine learning approaches were used to process a large number of shadowgraph images. Canny edge detection and Hough transform, as well as a convolutional neural network (CNN) based on YOLOv2 architecture, were used to automatically track the position of the bow shock relative to the body. Jet sound generation was studied - the amplitude dependence on the distance from the nozzle and the evolution in time. The position of the bow shock relative to the streamlined body and flow pulsations over time were analyzed. Bow shock pulsation spectra at zero angle of attack were compared to those at a small angle of attack (α = 2.5°–3°). The power spectral density was also estimated. The slope of the spectra for the zero angle of attack case was found to be horizontal and the spectra for the small angle of attack case had a slope close to −5/3. The strongest of the measured bow shock frequencies were found to be close to those of the jet mixing layer pulsations. The hardware signal spectrum was also measured and this signal can be considered as noise. The described approach makes it possible to obtain the physical characteristics of the flow at any point of interest. It was also shown that the automation of flow visualization experiments using computer vision techniques allows to increase the speed of data processing and obtaining new physical information, which may be important for engineers developing aircraft and spacecraft technologies.

Ternary Dry Powder Agglomerate Inhalation Formulation of Melatonin With Air Jet Mixing to Improve In Vitro And In Vivo Performance

An improved agglomerate formulation with melatonin and fine lactose for dry powder inhalation using Turbuhaler® was developed. Co-grinding lactose with 1 % magnesium stearate prior to air jet mixing served as a key factor to improve the in vitro aerosolization and in vivo efficacy. Elevated mixing pressure facilitated the dispersion and homogenization of the cohesive mixture for even distribution of agglomerate size after spheroidization and subsequent higher emitted dose with lower variation. Magnesium stearate was employed as a tertiary component to adjust the interparticle force for better aerosolization. At optimized mixing pressure, co-grinding lactose with magnesium stearate before jet mixing displayed further improvement of fine particle fraction to 71.6 ± 3.1 %. The superior fine particle deposition efficiency contributed to rapid onset of action and a high bioavailability of 67.0 % after intratracheal administration to rats. Overall, an inhalable melatonin dry powder formulation exhibiting good aerosol property and lung deposition with clinical translation potential was developed.

Using extruded circular multi-injectors to improve fuel jet mixing and distribution in combustion chambers of scramjet

An extensive investigation of multi-nozzle with various heights is done for enhancing the fuel mixing and distribution in supersonic combustion chambers of scramjets by using Computational Fluid Dynamics. Fuel injection and mixing play a crucial role in many industries, including automotive. This study examines the mechanism of hydrogen fuel jet mixing when injected through a multi-nozzle with varying heights in the combustion chamber of a scramjet. The impact of different injector height configurations on supersonic cross-flow is analyzed through computational fluid dynamics, and the flow and fuel mixing are evaluated to determine the most efficient fuel injection setup. A comparison is made between the proposed multi-jet configurations and simple multijet configurations to identify the primary hydrodynamic and mixing benefits of multi-jet configuration with different heights. The findings indicate that the use of multi-jet injectors with different heights decreases the circulation factor and improves fuel mixing downstream of four jets by 40 %.

Effect of velocity ratio and Mach number on thin lip coaxial jet

Abstract The effect of nozzle lip thickness and velocity ratio on coaxial subsonic jet mixing, at different Mach numbers, has been studied experimentally and numerically. Decay of coaxial subsonic jets emanating from coaxial nozzles of lip thickness 0.7, 1.7 and 2.65 mm with velocity ratio (VR) from 0.2 to 1.0 at primary jet exit Mach numbers of 0.6, 0.8 and 1.0 has been studied. Free jet without co-flow (VR0) was also studied for comparison. Jet centerline Mach number decay, turbulence and velocity variation in the radial direction are analyzed. The results show that mixing the coaxial jet at a low-velocity ratio is better than a high-velocity ratio, at all Mach numbers of the present study. The nozzle lip thickness has a significant influence on the secondary jet. Mixing of the jet in the presence of VR0.2 coaxial jet is found to be the highest. Characteristic decay of Mach 0.8 and 1.0 jet for lip thickness 1.7 and 2.65 mm is faster than lip thickness 0.7 mm. For a given lip thickness, increasing of velocity ratio is found to retard the mixing between primary and secondary jets.

Application of multi-extruded fuel injectors for mixing enhancement of hydrogen gas at scramjet engine: computational study.

Scramjet engines are considered a highly promising technology for improving high-speed flight. In this study, we investigate the effects of using multi-extruded nozzles on fuel mixing and distribution inside the combustion chamber at supersonic flow. Additionally, we explore the impact of an inner air jet on fuel mixing in annular nozzles. To model fuel penetration in the combustor, we employ a computational technique. Our study compares the roles of three different extruded injectors on fuel diffusion and distribution at supersonic cross-flow. Our findings reveal that the use of an inner air jet increases fuel mixing in the annular jet, while the use of extruded nozzles improves fuel distribution by enhancing the vortices between injectors. These results demonstrate the potential benefits of incorporating multi-extruded nozzles and inner air jets in the design of scramjet engines.

Preparation of Well-Defined Fluorescent Nanoplastic Particles by Confined Impinging Jet Mixing

Preparation of Well-Defined Fluorescent Nanoplastic Particles by Confined Impinging Jet Mixing

Stochastic modeling of multiple scalar mixing in a three-stream concentric coaxial jet based on one-dimensional turbulence

Modeling turbulent mixing is a standing challenge for nonpremixed chemically reacting flows. Key complications arise from the requirement to capture all relevant scales of the flow and the necessity to distinguish between turbulent advective transport and molecular diffusive transport processes. In addition, anisotropic mean shear, variable advection time scales, and the coexistence of turbulent and nonturbulent regions need to be represented. The fundamental issues at stake are addressed by investigating multi-scalar mixing in a three-stream coaxial jet with a map-based stochastic one-dimensional turbulence model. ODT provides full-scale resolution at affordable costs by a radical reduction of complexity compared to high-fidelity Navier–Stokes solvers. The approach is partly justified by an application of the boundary-layer approximation, but neglects fluctuating axial pressure gradients. It is demonstrated that low-order scalar statistics are reasonably but not fully captured. Despite this shortcoming, it is shown that the model is able to reproduce experimental state-space statistics of multi-stream multi-scalar mixing. The model therefore offers physics-compatible improvements in multi-stream mixing modeling despite some fundamental limitations that remain from unjustified assumptions.

Mach Number and Heating Effects on Turbulent Supersonic Jets

Modern experimental techniques were used to obtain detailed aerodynamic and thermodynamic data for turbulent supersonic jets. Operating points from the work of Seiner et al. for heated Mach 2 jets were used as a starting point for the matrix of cases examined here using a geometrically similar Mach 2 nozzle. Two additional nozzles were examined having design Mach numbers of 1.36 and 1.63. For each Mach number, multiple jet temperatures were investigated. Jet measurements were first made with stagnation pressure and temperature probes for comparison to the previous experiments. The experiments focused on modern nonintrusive measurement techniques, including particle image velocimetry for mean and root-mean-square (rms) velocities, and rotationally resolved Raman scattering spectroscopy for mean and rms temperatures. Experimental results showed that as jet Mach number increases, the overall jet mixing rate decreases, as indicated by the potential core length, downstream mean velocities, and turbulence levels. Similar behavior was observed in the mean temperatures and rms temperatures. The suppression of turbulence as the jet Mach number increases is due to compressibility. For a fixed jet Mach number, increasing the jet temperature resulted in faster mixing by all measures. Peak turbulent stress levels, located along the lipline of the jet, demonstrated trends in individual stress components that differed depending on whether jet Mach number or temperature was varied, but indicated that the turbulence structure parameter was very similar when varying either jet temperature or Mach number.

Direct numerical simulation of turbulent jet in regular waves: A comparison between circular and non-circular cross-sections

Direct numerical simulations of circular and non-circular jets (square and rectangular) when released into regular waves are performed and reported in this article. In case of a rectangular jet, two different orientations of the nozzle have been simulated i.e major axis parallel (case 1) and perpendicular (case 2) to wave advancement direction. An analysis of the leading vortex ring reveals that axis switching in a rectangular jet takes place irrespective of nozzle orientation with respect to wave advancement direction. The axis switching is absent in the square jet. Further, the roll-up frequency of the non-circular jets is found less than the circular jet. Also, the roll-up frequency is independent of the orientation of the rectangular jet with respect to the wave direction. The braid region shows that the number of counter-rotating pairs are four for all the cases, however, the lateral jets are three for circular, square and case 1 of rectangular jets. The lateral jets in case 2 of the rectangular jet remain four due to change in orientation of the lateral jets owing to change in the nozzle orientation. The time-averaged quantities suggest increased mixing and entrainment in the rectangular jet as compared to circular jet. The highest mixing and shortest potential core are observed in case 2 of the rectangular jet. Therefore, for better mixing, the rectangular nozzle should be placed in the ocean outfall such that its major axis remains perpendicular to the direction of wave advancement.

Fuel mixing enhancement of transverse coaxial air and fuel jet by upstream shock wave on in scramjet engines: numerical study

In this study, computational fluid dynamics (CFD) is used to disclose the impacts of upstream shock waves on fuel mixing of cross coaxial air and fuel jet at a scramjet engine. This study has tried to investigate the impact of three different lobe injectors (2-lobe, 3-lobe, and 4-lobe nozzle) on the fuel penetrations along the scramjet combustor. The supersonic air stream is M = 4 while cross hydrogen and air jet are released in sonic velocity. This study uses CFD simulations to analyze the effects of upstream shock waves on fuel mixing in the transverse coaxial jet and assess their potential for improving combustion efficiency. The results demonstrate that the usage of upstream shock waves significantly increases shock interactions and augments the vortex region downstream of the jet. Our results show that the impacts of shock waves on the penetration of fuel jet released from the coaxial lobe nozzle are substantial.

Mass spectrometric monitoring of ligand-bridged hot electron transfer and anaerobic oxidization on auto renewable droplet-based plasmonic nanoreactors under visible light illumination

The light induced hot-electron on plasmonic nanostructures has been recognized as a breakthrough discovery for photovoltaic and photocatalytic applications. With mass spectrometry, we demonstrate the dynamics of hot electron transfers of anaerobic oxidization reactions on Au decorated TiO2 plasmonic nanoparticles, which were coated on the inner surface of a flask. Those nanoparticles were covered by continuously renewed liquid droplets of solvent and reactants that were transported through a Venturi jet mixer with auto-spray. In addition to intensive mass transfer in such droplet-based nanoreactors, as well as strong adsorption of reactants and rapid desorption of products on materials surfaces, the localized surface plasmon resonance (LSPR) excitation upon visible light illumination, by which accumulated energies of plasmons are transferred to electrons in the conduction band of the material, attributes to the efficient photocatalytic transformation. Mass spectrometric detection of intermediate radical anions and negative ions with stable isotope labeling unambiguously identifies that highly energetic hot electrons can escape from the plasmonic nanostructures, be collected by adsorbed molecules, and initiate bond cleavages. It was demonstrated that losses of two H atoms result in the anaerobic oxidization of each benzyl alcohol molecule to a benzyl aldehyde molecule in the absence of molecular oxygen with more than 90 % yields. The well recyclable plasmonic nanoreactors implicate the injection of transferred electrons eventually back to electronically depleted Au+ positive ions. Bridged by adsorbed molecules, electrons were repeatedly circulated back and forth in plasmonic nanoreactors, where the collected light was eventually converted into chemical energy.

Studies on a Novel Jet Mixer in the Extraction Process

This paper presents the original results of research on an inline jet mixer being an alternative to other, conventional mixing apparatuses used for extraction processes. In particular, researched novel geometry of a jet mixer was subjected to testing of either hydraulic performance or a liquid–liquid extraction process. Inline jet mixers are well suited for mixing gases and liquids and can be used in such processes as extraction, heat exchange, and reaction. In such an apparatus, mixing of liquids takes place by high-velocity injection of one stream into another through a series of small holes placed peripherally to a concentrically mounted inner tube. The literature lacks the data to allow for the design of these types of mixers. Extraction experiments were performed for the ethyl acetate–ethanol–water system. The research results presented in this paper enable the calculation of mixing power and the selection of optimal mixer operating parameters. Equations describing the flow resistance for both streams were developed. The mixing power was calculated and compared with other types of contactors. The data on overall volumetric mass transfer coefficients obtained by this study showed that the considered extractor is competitive with other conventional contactors at almost identical or even lower energy consumption.

Experimental investigation of performance and soot emissions of oxygenated fuel blends in a small aero engine

Recent studies show that mixing jet fuel with oxygenated fuels has an impact on exhaust gas soot formation. Soot particles are an environmental hazard with an impact on air quality around airports, and possibly influencing ice crystal nucleation, leading to contrail and ice cloud (cirrus) formation. These ice clouds significantly warm up the atmosphere by reflecting heat radiation back to Earth and, at the same time, being transparent to incoming sunlight. Many investigations concentrate on reducing aviation’s CO2 footprint, but only a few account for reducing soot emissions in aero engines. This study examines the potential of blending Jet A-1 with oxygenated fuels to decrease soot particle formation in aero engines. For this, blends with 5 vol% and 20 vol% of ethanol, and 5 vol% of a polyoxymethylene dimethyl ether 3–5 mix (OME3-5 mix) are investigated in an Allison 250-C20B turboshaft engine with the help of a condensation particle counter (CPC). The results show tendencies in soot particle reduction, which, in most cases, is larger than the volumetric percentage of the oxygenated fuel within the blend.

Preparation of nano‐silver electromagnetic interference shielding functional coating on PC+ABS plastic via Ar/H2 mixed atmospheric pressure plasma jet

AbstractMetal coatings with micron thickness, high conductivity, and a unique structure that can provide exceptional electromagnetic interference (EMI) shielding performance to insulation substrates are highly desirable, especially if the production method is inexpensive, pollution‐free, and efficient. In this study, the Ar/H2 mixed atmospheric pressure plasma jet (APPJ) was utilized to reduce AgNO3 to produce PC + ABS substrates coated with silver nanoparticles (AgNPs). It was found that the low roughness AgNPs coating has a multilayer network structure, which could exhibit high conductivity and excellent EMI shielding effectiveness (SE). In conclusion, this method is an excellent choice for producing metal EMI shielding coating.