Liquid Jet Injection Research Articles

Multiscale numerical modeling of a complete spray evolution including breakup of liquid jet injection in gaseous cross flow

A direct coupling of the Volume of Fluid method (VOF) and the Lagrangian Particle Tracking (LPT) technique within a Large Eddy Simulation (LES) framework is revisited and assessed by numerically investigating a liquid jet injection into a cross-flowing air (JICF). To close the subgrid scale (SGS) terms appropriate SGS models are considered. In particular, an interfacial SGS term is included into the VOF scalar transport equation in order to achieve a suitable LES and to describe properly the liquid column and the break-up processes (primary and secondary). The dilute spray region including the droplets resulting from the secondary breakup is solved using the LPT approach. Since the latter allows the cell size to be multiple times larger than the droplet diameter, this reduces the computational expenses significantly making it possible to handle the simulation of the whole spray evolution including the complete liquid atomization without complex tunable atomization models. For this purpose, two operating conditions of a JICF existing in the literature are considered. The achieved results are first presented in terms of mesh sensitivity, required computational costs and impact of the interfacial SGS term. Next, comparisons between pure VOF/LES and VOF/LPT/LES for both qualitative features and quantitative properties are provided and discussed. In overall, a good agreement with experiments for the quantitative properties is reported. It is especially found that both the Rosin–Rammler and Gaussian distributions offer nearly a more accurate fit to the particle size distribution except for the range from 0 to 10 μm. Together with the detailed characteristics of vortices evolving and an extended breakup regime map, the spray characteristics including the spray structure are well captured. Finally, even though the interfacial SGS term has an evident influence on the jet and atomization dynamics, its impact on quantitative properties is not so prominent under these operating conditions.

Experimental study of the injection angle impact on the column Waves: Wavelength, frequency and drop size

An experimental study was performed to investigate the influence of injection angle on further details of breakup of a circular liquid jet injected into an airstream. Wavelength and frequency of axial oscillations caused by column waves, drops size distribution, orientation and aspect ratio of these drops were measured and reported. Injection angles between 30 and 90 degrees were considered. High-speed photography and shadowgraphy techniques were utilized to visualize and record the flow. Experimental data were obtained by processing images with the help of an in-house developed code. We found that gas Weber number and the injection angle are influential on wavelength and frequency of the column waves. The wavelength decreased and the frequency increased with increasing gas Weber number or decreasing the injection angle. Also, momentum ratio, gas Weber number and injection angle were affecting drop's average diameter. By reducing the injection angle, the atomization process was prolonged and the produced drops were larger. Although the injection angle affected the average drop size and number, as long as the regime was not changed, the probability distribution of drop size was independent of the injection angle.We extended theory of Ng et al. [1] to estimate wavelength, frequency of column waves formed on the liquid jet that was injected into an airstream to account for injection angle. A relative gas Weber number was defined by using the relative velocity of the gas to that of the liquid along the flow direction. The introduced relative gas Weber number was found useful in classifying the breakup regimes of the flow. A relation was proposed to estimate these wavelengths with good agreement with our data at different injection angles and other previously published data at normal injection of liquid jets. Two separate correlations for SMD estimation were proposed for before and after bag formation in the flow.

Liquid jet breakup in gaseous crossflow injected through a large diameter nozzle

Near nozzle field behavior of round liquid jets injected through large injector diameter (ranging from 0.2 to 0.6 m) into subsonic uniform gaseous crossflows is numerically investigated using the Volume of Fluid (VoF) method. The liquid jet to gas momentum ratio is ranging from 4.3 to 39 with a gas Weber number ranging from 1.6×104 to 5.3×104. The large scale liquid water column main properties, such as primary breakup process, liquid column penetration height, liquid column expansion and column breakup point location are studied. Effects of several parameters on the liquid column evolution are investigated, namely the diameter injector, the liquid jet injection velocity and the gaseous crossflow velocity. It has been found that the surface breakup and column breakup mechanisms are both contributing to the liquid column fragmentation. The fragmentation at large scale is characterized by the generation of a significant number of well developed arm and leg structures that align with the airflow on the side and at the bottom of the liquid column. Correlations for the main liquid jet properties are proposed and compared with results previously obtained for smaller size liquid jet. Liquid column penetration height, width and column breakup height follow the same type of power laws that those observed for liquid jet at smaller size. The liquid jet evolution is compared to the water jet generated by the B747 airtanker.

Solution of the Inverse Problem of Calculating a Gas–Liquid Injector with a Two-Phase Flow

We consider the possibility of solving the inverse problem of calculating a gas–liquid jet injector with a bubbly two-phase flow structure. The parameters governing the injector operation, such as the pressure difference, the orifice diameter, and the air concentration, are determined for the given value of the mean Sauter diameter. For this purpose, the operation of a mixer with a two-phase working body and injectors of different diameters was experimentally investigated in the bubbly operation regime with a water–air working body. In the experiments the parameters of the phases supplied to the mixer (flow rates, pressures, and temperatures) were measured, together with the pressure ahead of the injector. The dispersity and velocity parameters in the spray were measured using the laser shadow method. The statistics thus gathered allow one to obtain the required correlation dependences which makes it possible to solve the problem formulated.

Liquid film and heat transfer characteristics during superheated wall cooling via pulsed injection of a liquid jet

Pulse firing is one of the major operation modes of bipropellant thrusters for the attitude control of small-scale spacecrafts. In the pulse-firing mode, the operational range of the thruster depends on the deterioration of liquid film cooling performance. Because cooling performance is determined by the balance of heat removed by the liquid film and transferred to the manifold, the behavior and heat transfer characteristics of liquid films under the intermittent injection of liquid jets must be understood to enable a wider range of operational patterns. We conducted cooling tests on a superheated metal plate via the pulsed injection of a liquid jet for better understanding of the pulsed cooling process. Different injection patterns, including continuous injection, with the same injection quantity were examined on two types of metal plates (aluminum alloy and copper), because the thermal properties of metal plates affect both the heat transfer characteristics of the liquid film and temperature rise of the plate during the inter-pulse duration. The cooling process was evaluated based on the evolution of the liquid film on the metal plate and rear-side temperature of the metal plate. The evolution and temperature were simultaneously visualized using a high-speed camera and infrared camera, respectively. To link the liquid film state to the heat transfer process, the temperature and heat flux on the cooled surface were estimated by solving the inverse problem of three-dimensional transient heat conduction. The results indicate that the wetting front position corresponds to the position of the maximum temperature gradient. Additionally, the residual liquid film is consumed through the evaporation and the droplet dispersion related to the nucleate boiling. The effects of thermal inertia and diffusivity of the metal plate highlight the differences in the amount of heat removed by the liquid film. The heat removed by the liquid film during pulsed cooling exhibited a peak and was higher than that removed by continuous injection on the aluminum alloy plate. Less heat was removed under low-duty-cycle conditions, and the amount of heat removed by the liquid film was lower than that removed by continuous injection on the copper plate.

Liquid jet injection in supersonic crossflow: Self-induced jet oscillations and its effects

Liquid jet injection into supersonic crossflow is one of the conceptually simple ways of fuel atomization in Scramjet engines. In the present work, we experimentally investigate the flow and spray formed due to the injection of a liquid jet in supersonic crossflow with free stream Mach number of M∞ = 2.5. The main focus of the work is on the unsteady aspects of the flow and spray, which are found to be self-induced and occur naturally in the flow. High speed shadowgraphy shows large variations in the windward spray edge and penetration with time. Unsteady pressure measurements in the liquid injection line show that in the presence of a supersonic crossflow, there exist significant self-generated mass flow fluctuations that occur in the injection line. The frequency of these oscillations is seen to be close to a Strouhal number, St = fδ /U∞ ≈ 0.007, close to the typical low frequencies seen in Shock-Wave Boundary Layer Interaction studies (δ = boundary layer thickness). The variations in mass flow rate within the injection line leads to significant fluctuations of the spray penetration and shocks. In particular, the variations in spray penetration with time is observed to lead to significant variations in both the droplet numbers and size at a given location in the generated spray, which can have significant implications for applications where such configurations are used.

Design and Analysis: Servo-Tube-Powered Liquid Jet Injector for Drug Delivery Applications

The current state of commercially available needle-free liquid jet injectors for drug delivery offers no way of controlling the output pressure of the device in real time, as the driving mechanism for these injectors provides a fixed delivery pressure profile. In order to improve the delivery efficiency as well as the precision of the targeted tissue depth, it is necessary to develop a power source that can accurately control the plunger velocity. The duration of a liquid jet injection can vary from 10 to 100 ms, and it generate acceleration greater than 2 g (where g is the gravity); thus, a platform for real-time control must exhibit a response time greater than 1 kHz and good accuracy. Improving the pioneering work by Taberner and others whereby a Lorentz force actuator based upon a voice coil is designed, this study presents a prototype injector system with greater controllability based on the use of a fully closed-loop control system and a classical three-phase linear motor consisting of three fixed coils and multiple permanent magnets. Apart from being capable of generating jets with a required stagnation pressure of 15–16 MPa for skin penetration and liquid injection, as well as reproducing typical injection dynamics using commercially available injectors, the novelty of this proposed platform is that it is proven to be capable of shaping the real-time jet injection pressure profile, including pulsed injection, so that it can later be tailored for more efficient drug delivery.

Needle-Free Jet Injectors and Nanosuspensions: Exploring the Potential of an Unexpected Pair.

Needle-free liquid jet injectors are medical devices used to administer pharmaceutical solutions through the skin. Jet injectors generate a high-speed stream of liquid medication that can puncture the skin and deliver the drug to the underlying tissues. In this work, we investigated the feasibility of using liquid jet injectors to administer nanosuspensions, assessing the impact of the jet injection on their pharmaceutical and physicochemical properties. For this purpose, the model drug diclofenac was used to prepare a set of nanosuspensions, stabilized by poloxamer 188, and equilibrated at different pHs. The hydrodynamic diameter and morphology of the nanocrystals were analyzed before and after the jet injection across porcine skin in vitro, together with the solubility and release kinetics of diclofenac in a simulated subcutaneous environment. The efficacy of the jet injection (i.e., the amount of drug delivered across the skin) was evaluated for the nanosuspension and for a solution, which was used as a control. Finally, the nanosuspension was administered to rats by jet injector, and the plasma profile of diclofenac was evaluated and compared to the one obtained by jet injecting a solution with an equal concentration. The nanosuspension features were maintained after the jet injection in vitro, suggesting that no structural changes occur upon high-speed impact with the skin. Accordingly, in vivo studies demonstrated the feasibility of jet injecting a nanosuspension, reaching relevant plasma concentration of the drug. Overall, needle-free jet injectors proved to be a suitable alternative to conventional syringes for the administration of nanosuspensions.

Droplet evaporation of water and fuel jets in low and high temperature subsonic crossflows

Water and Jet A fuel were injected into low and high temperature crossflows of 65 °C and 425 °C, respectively, at a fixed crossflow pressure of 100 kPa, a liquid jet to gaseous crossflow momentum flux ratio of 7.5, and a crossflow Mach number of 0.175. Liquid jet injection temperature was also varied between 20 °C and 90 °C. The orifice had a diameter of 1 mm and a length of 20 mm. Visualization of the spray primary breakup processes was achieved using high-speed imaging. Droplet characteristics were measured at cross-sectional planes 300 mm, 400 mm, and 500 mm downstream of the orifice using a 2-component phase Doppler particle anemometry system. Results discussed included the variation of liquid volume flux, droplet size, and droplet velocities with increasing distance downstream of the injector. Analysis of the results revealed distinct changes in local and global droplet characteristics for both test liquids when injected into the high temperature crossflow compared to the low temperature crossflow. These changes, including increases in measured droplet size, were more significant at the bottom of the spray plume, especially for Jet A, due to the preferential heat-up and evaporation of droplets based on size and liquid thermal properties. For Jet A droplets smaller than 5 μm evaporated completely, leaving behind larger droplets that resisted evaporation. Increasing jet injection temperature was observed to reduce droplet size at a fixed crossflow velocity by reducing liquid surface tension which enhanced atomization. Higher liquid jet injection temperatures also resulted in increased droplet evaporation that initiated closer to the orifice exit.

Beef tallow injection matrix for serial crystallography

Serial crystallography (SX) enables the visualization of the time-resolved molecular dynamics of macromolecular structures at room temperature while minimizing radiation damage. In SX experiments, the delivery of a large number of crystals into an X-ray interaction point in a serial and stable manner is key. Sample delivery using viscous medium maintains the stable injection stream at low flow rates, markedly reducing sample consumption compared with that of a liquid jet injector and is widely applied in SX experiments with low repetition rates. As the sample properties and experimental environment can affect the stability of the injection stream of a viscous medium, it is important to develop sample delivery media with various characteristics to optimize the experimental environment. In this study, a beef tallow injection matrix possessing a higher melting temperature than previously reported fat-based shortening and lard media was introduced as a sample delivery medium and applied to SX. Beef tallow was prepared by heat treating fats from cattle, followed by the removal of soluble impurities from the extract by phase separation. Beef tallow exhibited a very stable injection stream at room temperature and a flow rate of < 10 nL/min. The room-temperature structures of lysozyme and glucose isomerase embedded in beef tallow were successfully determined at 1.55 and 1.60 Å, respectively. The background scattering of beef tallow was higher than that of previously reported fat-based shortening and lard media but negligible for data processing. In conclusion, the beef tallow matrix can be employed for sample delivery in SX experiments conducted at temperatures exceeding room temperature.

Needle-free Mental Incisive Nerve Block:In vitro, Cadaveric, and Pilot Clinical Studies

The present study aimed to optimize Needle-Free Liquid Jet Injection (NFLJI) for Mental Incisive Nerve Blocks (MINB) and evaluate its clinical safety and feasibility. A MINB protocol was developed and optimized by series of NFLJI experiments in soft tissue phantoms and cadavers, then validated in two pilot Randomized Controlled Trials (RCT). The NFLJI penetration depth was found to be directly proportional to the supply pressure and volume. High-pressure NFLJIs (620 kPa or above) created maximum force and total work significantly greater than needle injections. Low-pressure NFLJIs (413 kPa), however, produced results similar to those of needle injections. Additionally, high-pressure NFLJIs created jet impingement pressure and maximum jet penetration pressure higher than low-pressure NFLJIs. Pilot RCTs revealed that high-pressure NFLJI caused a high risk of discomfort (60%) and paresthesia (20%); meanwhile, low-pressure NFLJI was less likely to cause complications (0%). The preliminary success rates of MINB from cadavers using NFLJIs and needles were 83.3% and 87.5%. In comparison, those from RCTs are 60% and 70%, respectively. To conclude, NFLJI supply pressure can be adjusted to achieve effective MINB with minimal complications. Furthermore, the cadaver study and pilot RCTs confirmed the feasibility for further non-inferiority RCT.

How can smart dressings change the future of wound care?

How can smart dressings change the future of wound care?

Fixed-target serial femtosecond crystallography using in cellulo grown microcrystals.

The crystallization of recombinant proteins in living cells is an exciting new approach in structural biology. Recent success has highlighted the need for fast and efficient diffraction data collection, optimally directly exposing intact crystal-containing cells to the X-ray beam, thus protecting the in cellulo crystals from environmental challenges. Serial femtosecond crystallography (SFX) at free-electron lasers (XFELs) allows the collection of detectable diffraction even from tiny protein crystals, but requires very fast sample exchange to utilize each XFEL pulse. Here, an efficient approach is presented for high-resolution structure elucidation using serial femtosecond in cellulo diffraction of micometre-sized crystals of the protein HEX-1 from the fungus Neurospora crassa on a fixed target. Employing the fast and highly accurate Roadrunner II translation-stage system allowed efficient raster scanning of the pores of micro-patterned, single-crystalline silicon chips loaded with living, crystal-containing insect cells. Compared with liquid-jet and LCP injection systems, the increased hit rates of up to 30% and reduced background scattering enabled elucidation of the HEX-1 structure. Using diffraction data from only a single chip collected within 12 min at the Linac Coherent Light Source, a 1.8 Å resolution structure was obtained with significantly reduced sample consumption compared with previous SFX experiments using liquid-jet injection. This HEX-1 structure is almost superimposable with that previously determined using synchrotron radiation from single HEX-1 crystals grown by sitting-drop vapour diffusion, validating the approach. This study demonstrates that fixed-target SFX using micro-patterned silicon chips is ideally suited for efficient in cellulo diffraction data collection using living, crystal-containing cells, and offers huge potential for the straightforward structure elucidation of proteins that form intracellular crystals at both XFELs and synchrotron sources.

Needle-free injection: Dental infiltration anesthesia

This study aimed to develop an optimal Needle-Free Liquid Jet Injection (NFLJI) technique for dental infiltration anesthesia and evaluate its clinical safety and feasibility. The fluid dynamics of NFLJI in the dentoalveolar region were investigated using soft tissue phantoms supported by rigid glass. NFLJIs were performed at different incident angles and recorded using a high-speed camera. Accordingly, an optimal NFLJI for infiltration anesthesia was developed and validated on cadavers, then assessed in two pilot Randomized Controlled Trials (RCT): one for validating the safety of optimal NFLJI technique, the other for evaluating its feasibility and safety. High-speed videos showed that perpendicular NFLJIs induced significantly more regurgitation than oblique NFLJIs, which was confirmed in cadavers. Clinical trials revealed that perpendicular NFLJIs induced a high risk of bleeding (83.3%) and laceration (83.3%), whereas oblique NFLJIs induced a low risk of bleeding (33.3%) and laceration (16.7%). Moreover, the preliminary success rates of oblique NFLJIs and needle injections were both 83.3%. The recruitment took 3–5 weeks with a rate of 100%. Oblique NFLJIs could be a promising approach for dental infiltration anesthesia, causing minimal drug regurgitation with a relatively low risk of complication. The pilot RCTs confirmed the feasibility for conducting a non-inferiority RCT.

Miniaturized Needle Array-Mediated Drug Delivery Accelerates Wound Healing.

A major impediment preventing normal wound healing is insufficient vascularization, which causes hypoxia, poor metabolic support, and dysregulated physiological responses to injury. To combat this, the delivery of angiogenic factors, such as vascular endothelial growth factor (VEGF), has been shown to provide modest improvement in wound healing. Here, the importance of specialty delivery systems is explored in controlling wound bed drug distribution and consequently improving healing rate and quality. Two intradermal drug delivery systems, miniaturized needle arrays (MNAs) and liquid jet injectors (LJIs), are evaluated to compare effective VEGF delivery into the wound bed. The administered drug's penetration depth and distribution in tissue are significantly different between the two technologies. These systems' capability for efficient drug delivery is first confirmed in vitro and then assessed in vivo. While topical administration of VEGF shows limited effectiveness, intradermal delivery of VEGF in a diabetic murine model accelerates wound healing. To evaluate the translational feasibility of the strategy, the benefits of VEGF delivery using MNAs are assessed in a porcine model. The results demonstrate enhanced angiogenesis, reduced wound contraction, and increased regeneration. These findings show the importance of both therapeutics and delivery strategy in wound healing.

Analysis of Multi-Hit Crystals in Serial Synchrotron Crystallography Experiments Using High-Viscosity Injectors

Serial Synchrotron Crystallography (SSX) is rapidly emerging as a promising technique for collecting data for time-resolved structural studies or for performing room temperature micro-crystallography measurements using micro-focused beamlines. SSX is often performed using high frame rate detectors in combination with continuous sample scanning or high-viscosity or liquid jet injectors. When performed using ultra-bright X-ray Free Electron Laser (XFEL) sources serial crystallography typically involves a process known as ’diffract-and-destroy’ where each crystal is measured just once before it is destroyed by the intense XFEL pulse. In SSX, however, particularly when using high-viscosity injectors (HVIs) such as Lipidico, the crystal can be intercepted multiple times by the X-ray beam prior to exiting the interaction region. This has a number of important consequences for SSX including whether these multiple-hits can be incorporated into the data analysis or whether they need to be excluded due to the potential impact of radiation damage. Here, we investigate the occurrence and characteristics of multiple hits on single crystals using SSX with lipidico. SSX data are collected from crystals as they tumble within a high viscous stream of silicone grease flowing through a micro-focused X-ray beam. We confirmed that, using the Eiger 16M, we are able to collect up to 42 frames of data from the same single crystal prior to it leaving the X-ray interaction region. The frequency and occurrence of multiple hits may be controlled by varying the sample flow rate and X-ray beam size. Calculations of the absorbed dose confirm that these crystals are likely to undergo radiation damage but that nonetheless incorporating multiple hits into damage-free data should lead to a significant reduction in the number of crystals required for structural analysis when compared to just looking at a single diffraction pattern from each crystal.

Cooling of The Heated Wall Surface by Liquid Film during A Repetitive Pulsed Injection of Liquid Jet

Cooling of The Heated Wall Surface by Liquid Film during A Repetitive Pulsed Injection of Liquid Jet

DNS and LES of primary atomization of turbulent liquid jet injection into a gaseous crossflow environment

In this paper, we study the primary atomization characteristics of liquid jet injected into a gaseous crossflow through direct numerical simulations (DNS) and large eddy simulations (LES). The DNS use a coupled level set volume of fluid (CLSVOF) sharp interface capturing method resolving all relevant scales to predict the drop size distribution (DSD) for drops larger than the grid spacing. The LES use a volume of fluid (VOF) diffused interface method modelling the sub grid droplets. The purpose of this paper is to provide a comparison of the results of drop data between DNS and LES. The simulations are performed for a liquid jet injection with liquid-gas momentum flux ratio of 6.6, liquid jet Reynolds number of 14,000 injected into a crossflowing air with Reynolds number 570,000 and Weber number of 330 at a liquid-to-gas density ratio of 10. Two distinct and simultaneous atomization/breakup mechanisms have been observed in the simulations: column/bag breakup and ligament/surface breakup. It was found that the DSDs obtained from the DNS and LES each follow a log-normal distribution based on their respective droplet diameter data. An overlap region exists between the individual DSDs from the DNS and LES when combined. The width of this overlap region decreases along the downstream direction. A log-normal distribution is found to be a good fit to the combined DSD incorporating both resolved and sub-grid droplets. This information is relevant for the secondary atomization simulations and modeling.

Biochemical and physical actions of hyaluronic acid delivered by intradermal jet injection route.

Administration of exogenous hyaluronic acid (HA) by liquid jet injection is considered as a beneficial therapy for dermatology conditions. This paper reviews variety of the factors which would optimize the clinical output of hyaluronic acid in this treatment modality. A pneumatically accelerated jet penetrates the epidermis and spherically spreads micro-droplets of HA in the dermis without significant damage to the tissue and blood vessels. Kinetic energy of the jet activates two parallel mechanisms of action-mechanical and biological-which act synergistically to initiate and augment the regenerative effect. Jet-induced micro-trauma stimulates collagen synthesis and tissue repair without inflammation. Aside from the biophysical stimulation of dermal fibroblast, the biomolecular properties of exogenous HA provide excellent clinical results for skin atrophy, remodeling of dermal scarring, and reverse formation of fibrotic tissue. The effect is mediated by HA-specific cell receptors and depends on molecular weight and the rheological properties of HA polymer. Skin mechanical properties play a key role in predicting HA dispersion patterns. Tolerability and safety of the treatment approach are determined by the jet's physical impact on the tissue and/or by the safety profile of the injected material. Although pneumatic jet delivery of a hyaluronic acid has a limited use in clinical practice, this treatment approach has a strong potential for extended implementation in esthetic dermatology. The synergistic mechanism has significant advantages of predictable and rapid clinical outcomes with a low discomfort. Additional well-designed investigations are required for establishing a scientific foundation and guidelines for this treatment modality.

Lard Injection Matrix for Serial Crystallography

Serial crystallography (SX) using X-ray free electron laser or synchrotron X-ray allows for the determination of structures, at room temperature, with reduced radiation damage. Moreover, it allows for the study of structural dynamics of macromolecules using a time-resolved pump-probe, as well as mix-and-inject experiments. Delivering a crystal sample using a viscous medium decreases sample consumption by lowering the flow rate while being extruded from the injector or syringe as compared to a liquid jet injector. Since the environment of crystal samples varies, continuous development of the delivery medium is important for extended SX applications. Herein, I report the preparation and characterization of a lard-based sample delivery medium for SX. This material was obtained using heat treatment, and then the soluble impurities were removed through phase separation. The lard injection medium was highly stable and could be injected via a syringe needle extruded at room temperature with a flow rate < 200 nL/min. Serial millisecond crystallography experiments were performed using lard, and the room temperature structures of lysozyme and glucose isomerase embedded in lard at 1.75 and 1.80 Å, respectively, were determined. The lard medium showed X-ray background scattering similar or relatively lower than shortenings and lipidic cubic phase; therefore, it can be used as sample delivery medium in SX experiments.