Jet Mixing Research Articles

Continuous Production of Docetaxel-Loaded Nanostructured Lipid Carriers Using a Coaxial Turbulent Jet Mixer with Heating System

The continuous synthesis of nanoparticles (NPs) has been actively studied due to its great potential to produce NPs with reproducible and controllable physicochemical properties. Here, we achieved the high throughput production of nanostructured lipid carriers (NLCs) using a coaxial turbulent jet mixer with an added heating system. This device, designed for the crossflow of precursor solution and non-solvent, combined with the heating system, efficiently dissolves solid lipids and surfactants. We reported the flow regime according to the Reynolds number (Re). Also, we confirmed the size controllability of NLCs as dependent on both Re and lipid concentration. The optimized synthesis yields NLCs around 80 nm, ideal for targeted drug delivery by enhanced permeability and retention (EPR) effect. The coaxial turbulent jet mixer enables effective mixing, producing uniform size distribution of NLCs. The NLCs prepared using the coaxial turbulent jet mixer were smaller, more uniform, and had higher drug loading compared to the NLCs synthesized by a bulk nanoprecipitation method, showcasing its potential for advancing nanomedicine.

ANALYSIS OF THEORETICAL STUDIES OF DEVICES FOR DOSING AND MIXING NUTRIENT SOLUTIONS

Fertigation systems play an important role in greenhouse crop production, which allow combining irrigation and fertilization processes, providing optimal plant nutrition. The main task of such systems is accurate dosing and uniform mixing of nutrient solutions, including different types of fertilizers, with water. Fertigation technology makes it possible to significantly reduce the loss of water and fertilizers, as well as to increase the efficiency of their use at various stages of plant growth. However, the effectiveness of these systems depends on the quality of the mixing and dosing devices, which must ensure the uniform distribution of nutrients in the solution. Today, there are different designs of mixers for the preparation of nutrient solutions: mechanical mixers with moving elements and static mixers that use hydraulic flows for mixing. Mechanical mixers are suitable for solid and hard-to-dissolve fertilizers, but their operation is complicated by the presence of moving parts. Static mixers are easier to use and have no moving parts, making them efficient and reliable for fertigation systems. The analysis of theoretical studies of devices for dosing and mixing nutrient solutions, in particular, jet mixers that work according to the static principle, has been carried out. The considered devices for preparing liquid mixtures are of the ejector type, on the basis of which many modern systems are built. The main attention is paid to the calculations of the optimal geometrical parameters of jet dispensers-mixers. The theoretical studies of most scientists are focused on determining the injection coefficient — as a key parameter that determines the efficiency of mixing and dosing. Theoretical approaches also include models of turbulent particle transport and semi-empirical equations to evaluate mixing quality. However, the issue of practical assessment of the quality of multi-component mixer-dispenser mixtures remains insufficiently studied.

Experimental Study on the Output Characteristics of a Novel Intensifier Controlled by an Electromagnetic Valve

The application of ultra-high-pressure (UHP) water jets for rock slotting in the bottom hole has been recognized as a highly effective approach to enhance rock-breaking efficiency. However, the current downhole intensifiers are confronted with various limitations, including the short duration of UHP pulse water jet output and challenges in attaining both controllable and adjustable output frequencies, consequently leading to compromised slotting efficiency. In this study, a novel intensifier controlled by an electromagnetic valve was designed, and a visual test platform was constructed to investigate the output pressure characteristics and their influencing factors. The output characteristics of the intensifier consist of a mixed pulse jet composed of high-pressure and low-pressure jets, resulting in a square wave-like output waveform with an adjustable frequency. The output pressure characteristics of the intensifier are primarily influenced by the input pressure and the switching time of the electromagnetic valve, assuming that the structural parameters are constant. Increasing the input pressure raises the peak pressure, thereby enhancing the slotting capability of the jet stream. Aligning the switching time of the electromagnetic valve with the rotation period of the drill bit improves the slotting efficiency. In the lab tests, the output pressure of the intensifier was successfully increased to 118.2 MPa, with a sustained duration of a high-pressure jet segment for 2.1 s. These research findings offer a new method for enhancing drilling efficiency in deep hard rock formations.

An innovative vortex generator for promoting subsonic and sonic jet mixing

An innovative vortex generator for promoting subsonic and sonic jet mixing

Numerical comparison of exhaled particle dispersion and infection probability in hospital wards heated by mixing ventilation and impinging jet ventilation

Impinging jet ventilation has sufficient supply momentum to overcome thermal buoyancy, with the potential to reduce cross-infection risk in winter. Using an Eulerian-Lagrangian approach validated by experiments, this study compared the exhaled particle dispersion in a two-bed hospital ward heated by impinging jet ventilation and mixing ventilation. Exhaled particles with ten different diameters were tracked under four typical air changes per hour. Particle concentration distribution and residence time were compared. A revised Wells-Riley model was used to calculate the airborne infection probability of coronavirus disease 2019, with the help of a custom field function in Fluent software. The results indicated that impinging jet ventilation increased the air velocity in the occupied zone compared with mixing ventilation. The higher air velocity facilitated the control and removal of fine and medium particles, resulting in lower indoor particle concentration and shorter residence time for 0.5 – 10 μm particles under impinging jet ventilation. With the same air changes per hour, the average infection probability of coronavirus disease 2019 at the breathing zone of susceptible individuals under mixing ventilation could be 1.3 to 12.8 times higher than that under impinging jet ventilation. Additionally, the local infection probability at the face of susceptible individuals was lower under impinging jet ventilation. This study showed that impinging jet ventilation can be implemented in hospital wards to reduce the cross-infection during winter.

Experimental studying of vapor explosion triggering during the breakup of a molten salt jet

The paper presents an experimental study using high-speed video recording of the process of vapor explosion on a breakup jet of molten NaCl salt in water. The regimes of jet breakup into large parts, accompanied by the separation of small satellite droplets, have been studied. For the first time, the propagation of a vapor explosion on two large fragments of jet breakup due to spontaneous triggering of the process on a droplet-satellite was reproduced and recorded under laboratory conditions. The possibility of a vapor explosion occurring at the initial stage of the first stage of coarse crushing and mixing of the melt jet is shown.

Effects of additional transmission chamber on flow dynamics of a pulsed jet in crossflow

This study examines the effects of an additional transmission chamber on a pulsed jet in crossflow using experimental and Large-eddy simulation methods, with a focus on the structural and mixing characteristics of the flow. Three pulse frequencies are selected (f = 20 Hz, 50 Hz, and 100 Hz), and the results of the model with an additional transmission chamber are compared with the round pipe model. The results show that the additional transmission chamber enhances jet penetration, diffusion, and mixing uniformity, particularly at higher pulse frequencies. The additional transmission chamber also alters the exit velocity profile, increasing peak velocity and promoting greater deflection under crossflow. These findings highlight the potential of transmission chambers to optimize pulsed jet performance in applications requiring effective mixing and penetration.

Flow characterization of a submerged inclined impinging pulse jet

This study investigated flow characteristics associated with a circular pulse-impinging jet on an inclined surface using dye visualization and particle image velocimetry techniques. The experiments are carried out for various pulse frequencies (0.1 < St < 0.9) of the jet, a constant angle of surface inclination (θ = 26°), and fixed surface spacing. The primary objective is to explore the flow dynamics aspect of pulse-inclined impinging jets with respect to the pulse frequency and Reynolds number. The present observation shows that at a certain degree of surface inclination (θ ≈ 28°), the jet momentum drives the entire flow in the downhill direction, which represents the critical angle of inclination. Furthermore, the critical angle of the inclination remains unchanged for both steady and pulse jets. The interaction of the inner and outer shear layers of the jet in the downhill direction highly depends on the pulse frequency, which is indeed triggered by the free jet vortices. In a free jet, the vortex formation and their growth depend on the jet shear layer response (convective acceleration) and the time available for vortex formation (local acceleration). Moreover, the instantaneous jet information reveals that the presence of the growing vortices increases the jet entrainment, and its movement along the surface enhances the mixing (shear stress) between the surrounding and boundary layer fluid. The results show that pulsation at Strouhal Number (St) = 0.44 help develop more coherent and durable vortices impinging on the surface, which is identical to the critical St for free and normal impinging jets. Pulsation near the critical St increases the jet entrainment and mixing between the inner and outer jet shear layers and is responsible for enhancement in the heat transfer rate. The results improve our understanding of heat transfer from pulse-inclined impinging jet and reinforce the existence of a critical St (= 0.44) with an inclined pulsing jet, providing the criteria for maximizing the heat transfer rate.

Influence of high-speed jet on the particle distributions in downer

The large-scale cold model experiments are carried out to investigate the influence of high-speed jets on the distribution of particles in downer. The cases of both downward jets (co-current contact) and upward jets (counter-current contact) are studied. Generally, it is found that the solid holdups in the initial mixing zone of feed with particles are higher under the influence of counter-current jets, which could form the local “thickening” region in downer. To make a quantitative comparison, the radial non-uniformity index of solid holdups RNI(εs) in the jet mixing zone is calculated. Results show that the solid holdups in the counter-current jet mixing zone are more uniformly distributed in radial and the axial jet influence zone is shorter. By changing the jet gas velocity, its effects on the particle distributions are analyzed. Finally, based on experimental data, the distributions of solid holdups in co-current and counter-current jet influence zones of downer are formulated into formulas.

Dynamic modeling of air–metal plasma mixture of single-turn coil with erosion at megaGauss magnetic field

Single-turn coil (STC) is a destructive pulsed magnet aiming at 100–300 T magnetic field. Due to the high discharge current, the conductor of STC is heated rapidly and undergoes melting and vaporization, leading to the generation of supersonic air–metal vapor mixed plasma jet and the magneto-fluid effect. In this study, the mixed plasma mass-transfer and fluid dynamic characteristics are modeled at megaGauss magnetic field, high temperature, high pressure, and supersonic conductor shock deformation. The collision integral method is employed to calculate the fluid transport properties. In addition, a boundary constraint model of fluid–structure interaction (FSI) compatible with both fluid wall boundary condition and plasma jet entrance condition and a model to simultaneously solve the thermal ionization and high electric field ionization of the mixed vapor are proposed. As the result, the distributions of plasma electrical conductivity, current density, electron, heavy particles, temperature, air body load, and velocity are derived. Especially, the region of highest electrical conductivity is not the air domain near the inner surface of the conductor with the highest electron density and the highest magnetic field, but the air domain near the outer surface of the conductor with the relatively higher electron density and lower magnetic field.

Diblock Copolymer Targeted Lipid Nanoparticles: Next-Generation Nucleic Acid Delivery System Produced by Confined Impinging Jet Mixers.

Despite the recent advances and clinical demonstration of lipid nanoparticles (LNPs) for therapeutic and prophylactic applications, the extrahepatic delivery of nucleic acids remains a significant challenge in the field. This limitation arises from the rapid desorption of lipid-PEG in the bloodstream and clearance to the liver, which hinders extrahepatic delivery. In response, we explore the substitution of lipid-PEG with biodegradable block copolymers (BCPs), specifically poly(ε-caprolactone)-block-poly(ethylene glycol) (PCL-b-PEG). BCPs offer strong anchoring for large macromolecules, potentially enhancing cell-specific targeting. To develop and optimize BCP-stabilized LNPs (BCP-LNPs), we employed a Design of Experiment (DOE) approach. Through a systematic exploration, we identified optimal formulations for BCP-LNPs, achieving desirable physicochemical properties and encapsulation efficiency. Notably, BCP-LNPs exhibit surprising trends in transfection efficiency, with certain formulations showing up to a 40-fold increase in transfection in Hela cells, while maintaining minimal cytotoxicity. The lipid compositions that optimized PCL-b-PEG LNP transfection were different from the compositions that optimized PEG-lipid LNP transfection. Furthermore, our study confirms the versatility of BCP-LNPs in encapsulating and delivering both mRNA and pDNA, demonstrating their cargo-agnostic nature. Lastly, we showcased the targeted BCP-LNPs using a Cetuximab-conjugated formulation. These targeted LNPs show significant promise in delivering cargo specific to EGFR-overexpressing cells (A549 cells), with up to 2.4 times higher transfection compared to nontargeted LNPs. This finding underscores the potential of BCP-LNPs in targeted gene therapy, especially in challenging scenarios such as tumor targeting. Overall, our study establishes the viability of BCP-LNPs as a versatile, efficient, and targeted delivery platform for nucleic acids, opening avenues for advanced therapeutic applications.

Jet mixing optimization using a bio-inspired evolution of hardware and control

Jet mixing is a critical factor in various engineering applications, influencing pollutant dispersion, chemical processes, medical treatments, and combustion enhancement. Hitherto, jet mixing has typically been optimized by either passive or active control techniques. In this experimental study, we combine simultaneous optimization of active control with 12 inward-pointing minijets and a tuneable nozzle exit shape commanded by 12 stepper motors. Jet mixing is monitored at the end of the potential core with an array of 7 \\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\ imes$$\\end{document} 7 Pitot tubes. This high-dimensional actuation space is conquered with Particle Swarm Optimization through Targeted, Position-Mutated Elitism. Our results underscore the significant impact of combining control techniques, illustrating the complex interactions of both passive and active control on jet flow dynamics. The mixing area of the combined control optimization is 4.5 times larger than the area of the unforced state. This mixing increase significantly outperforms the effect of shape optimization of the nozzle alone. Our study points at the potential of optimization in high-dimensional design spaces for shapes as well as passive and active control—leveraging the rapid development of flow control hardware and the increasingly powerful tools of artificial intelligence for optimization.

Mixing enhancement with minimal thrust loss for the Mach 1.76 jet issuing from different beveled collar nozzles

The main objective of the present investigation is to enhance the jet mixing by introducing a nozzle collar exit inclination having bevel angles of 30°, 45°, and 60°. In addition to this, the present study also addresses the problem of investigating the jet which attains maximum mixing from beveled collar nozzle with the imposition of a minimal overall thrust loss penalty. The nozzles of the present study have been designed to deliver a uniform Mach 1.76 jet at the nozzle collar exit. The results thus obtained through numerical computations have been compared with that of the reference nozzle which has zero exit inclination. The investigations have been performed under both design and off-design conditions of the jet by varying the nozzle pressure ratio (NPR) from 4.5 to 6.5 with unit step size. It is seen that the rate of jet mixing is augmented with the increase in the bevel angle. Thus, the 60° beveled collar nozzle demonstrated the highest jet mixing in comparison to the reference nozzle, 30° and 45° beveled collar nozzle at each nozzle pressure ratio. However, 60° beveled collar nozzle has been substantially penalized with the highest thrust loss of about 6.5% at nozzle pressure ratio 4.5 and about 3.5% at nozzle pressure ratio 5.5 with respect to the reference nozzle and other nozzles of the present study. The 45° and 30° beveled collar nozzles reported the thrust penalty below 2.3% and 1%, respectively. The overall performance, which includes mixing enhancement along with the minimal thrust loss, has been found in the 45° beveled collar nozzle, which clearly justifies its preference over the other investigated nozzle configurations.

Large Eddy simulation on the Lead-Bismuth Eutectic jet at reactor core outlet

The Lead-Bismuth Eutectic (LBE) Cooled Fast Reactor (LFR) represents a promising Generation-IV technology, anticipated to offer a sustainable, safe, and clean energy solution. LBE fluid from LFR assemblies varies in temperature, causing violent temperature oscillations during the jet mixing that may contribute to structural fatigue, threatening LFR safety. This study focuses on investigating the critical thermal–hydraulic phenomena occurring at the core outlet of the LFR by modeling the assembly head in a realistic reactor configuration. Large Eddy Simulation (LES) is employed to explore the LBE jet characteristics in a three-head model with varying inlet parameters. The analysis includes the fluctuation patterns of both the flow and temperature fields downstream of the assembly head. The results show that the influence area of the assembly head is mainly in the range of about 0–175 mm downstream of the outlet of the assembly head. The temperature fluctuation frequency is the highest near the assembly head, typically within 20 Hz, and the temperature fluctuation frequency in other areas is lower. These findings provide valuable insights for designing LFRs and understanding the flow and heat transfer behavior of liquid metals.

Investigation of unswept ramp system with lobe shape nozzle for fuel mixing of hydrogen jet at a scramjet engine

The role of efficient fuel mixing and a stable flame holder is crucial in enhancing the performance and capabilities of scramjet engines for high-speed flight. The present research paper has tried to disclose the fuel mixing efficiency of 3-lobe annular nozzle on the mixing mechanism of the fuel jet behind the strut. In addition, using internal air jet flow for increasing the circulation strength and fuel mixing behind the strut is also examined in this study. Numerical simulation of the flow and fuel jet behind the strut is done to reveal the main physics related to the mechanism of fuel mixing inside the combustor with the proposed injection system. The results of our simulation show that using annular 3-lobe fuel jet improve the fuel mixing via production of the multiple vortex pairs within the combustor behind the strut. The use of internal air jet also enhances the fuel mixing efficiency up to 90% in combustor of scramjet engine.

Scalar mixing and entrainment in an axisymmetric jet subjected to external turbulence

The present study aims to understand the process of turbulent entrainment into a jet, as affected by background turbulence, using scalar statistics. Planar laser-induced fluorescence was employed to capture the orthogonal cross sections of the jet at a fixed downstream station with varying background turbulence intensities and length scales. The conditional scalar profiles revealed that the thickness of the scalar turbulent/turbulent interface is greater than that of the traditional turbulent/non-turbulent interface, and the interfacial thickness is an increasing function of the background turbulence intensity. Although nibbling remains the primary entrainment mechanism in the far field, increased occurrence of concentration “holes” within the interfacial layer in the presence of ambient turbulence suggests a more significant role of large-scale engulfment in the turbulent/turbulent entrainment process (although still below 1% of the total mass flux). Enhanced contribution of the area of detached jet patches (i.e., “islands”) to that of the main jet is hypothesized to be evidence of intense detrainment events in the background turbulence. This can potentially contribute to a reduced net entrainment into the jet, which manifests as less negative values of scalar skewness within the jet core.

Jet centrifugal pump internal flow numerical simulation and structural optimization

Abstract Jet centrifugal pump is essential equipment in multiple systems such as agricultural irrigation and energy production. This paper investigates the internal flow characteristics of jet centrifugal pumps at different flow rates and the cavitation behavior under high flow conditions by numerical simulation methods. Additionally, two performance optimization strategies are proposed based on simulation results. The findings indicate that high-velocity regions and low-pressure zones exist within the nozzle. As flow rate increases, the outlet velocity of the nozzle gradually decreases, and large areas of low pressure are observed near the inlet of the impeller. Cavitation occurs to varying degrees at flow rates of 4.056 m3/h and 3.840 m3/h. The turbulent kinetic energy contours for these conditions reveal uneven distribution within the jet nozzle, with higher values near the jet mixing layer, inner wall of the jet nozzle and impeller inlet. Structural optimization using hemispherical bolts significantly reduces the turbulent kinetic energy around the bolts, resulting in an increase in head ranging from 1.68% to 6.70% across various flow rates. Shortening the clearance between the impeller and the rear cover reduces energy losses, leading to an increase in head ranging from 2.72% to 5.86%.

Cause of nocturnal surface ozone enhancement in the North China Plain

The North China Plain (NCP), known for its dense population, extensive urbanization, and developed industry and agriculture, faces one of the foremost ozone (O3) pollution issues nationwide and even globally. Currently, most studies focus on daytime peak O3 levels, with insufficient understanding of the increase in nighttime O3 concentrations. Based on data from 204 national atmospheric composition monitoring sites in the NCP from 2015 to 2023, we investigated the characteristics of nocturnal surface O3 enhancement (NSOE) events and explored potential formation mechanisms. The mean annual frequencies of single-site and regional NSOE event in the NCP between 2015 and 2023 are 42 % and 21 %, respectively. The daytime peak O3 concentrations before and after NSOE events exceeded those during the corresponding periods of non-NSOE events by 84 ± 19 and 32 ± 15 μg/m3, respectively. The overall effect of the NSOE events was to decelerate the rate of decline in nighttime O3 concentrations and resulted in a reduction of NO2 and CO concentrations from 22:00 onwards. Low level jet (LLJ) and vertical mixing were the main factors affecting NSOE events in the NCP. The proportion of NSOE events affected by LLJ in four representative cities ranged from 57.6 % to 79.5 %. Furthermore, the high concentration of O3 in the residual layer before the NSOE event and the reduction of atmospheric stability during the NSOE event favored downward mixing of upper layer O3. The primary weather systems influencing the four most severe regional NSOE events were LLJ, typhoon, and cold fronts. The first two events were dominated by vertical mixing of O3, while the latter two events were mainly affected by horizontal transport. Our findings provide the first overview of NSOE events in the NCP from characteristics to mechanisms, emphasizing the necessity for future detailed studies based on nocturnal vertical O3 observations.

Quantification of the hetero-contact formation process for a CuO/CeO2 hetero-aggregate model system prepared by double flame spray pyrolysis

In hetero-aggregates, different materials form sintered hetero-contacts, which lead to new material properties. In this study, the influence of process parameters on the formation of hetero-contacts in Double Flame Spray Pyrolysis (DFSP) was quantified. The mixing of jets was monitored by Particle Image Velocimetry (PIV) measurements as well as by thermocouples and compared to the single flame setting. Overlap of the jets was evaluated using tracers to visualize the mixing zone. Ten CuO/CeO2 model material samples were prepared with different flame inclination angles, nozzle distances and different particle volume fractions. Mixing on hetero-aggregate level was quantified using Convolutional Neural Network (CNN) evaluations of STEM images, Temperature-Programmed Reduction (TPR) and Differential Centrifugal Sedimentation (DCS) disk centrifugation to determine cluster sizes and hetero-coordination numbers as mixing quantifiers. Here, good correlations between the differently measured quantifiers were observed.

Investigating the Energy Dissipation Mechanism of Piano Key Weir: An Integrated Approach Using Physical and Numerical Modeling

The enormous energy carried by discharged water poses a serious threat to the Piano Key Weir (PKW) and its downstream hydraulic structures. However, previous research on energy dissipation in PKWs has mainly focused downstream effects, and the research methods have been largely limited to physical model experiments. To deeply investigate the discharge capacity and hydraulic characteristics of PKW, this study established a PKW model with universally applicable geometric parameters. By combining physical model experiments and numerical simulations, the flow pattern of the PKW, the discharge at the overflow edges, and the variation in the energy dissipation were revealed for different water heads. The results showed that the discharge of the side wall constitutes the majority of the total discharge at low water heads, resulting in a relatively high overall discharge efficiency. As the water head increases, the proportion of discharge from the inlet and outlet keys increases, while the proportion from the side wall decreases. This change results in less discharge from the side wall and a consequent reduction in the overall discharge efficiency. The PKW exhibits superior energy dissipation efficiency under low water heads. However, this efficiency exhibits an inverse relationship with an increasing water head. The overall energy dissipation efficiency can reach 40% to 70%. Additionally, the collision of the water flows inside the outlet chamber and the mixing of the overflow jet play a primary role in energy dissipation. The findings of this study have significant implications for hydraulic engineering construction and PKW operational safety.