Jet Injection Research Articles

Flow Instability Control in a Model Swirl-Stabilized Combustor with Central Jet Injection

Swirling flows often occur in nature and industrial applications. With an increase in swirl intensity, such rotating flows are known to become unstable and undergo a sudden breakdown of the vortex core, resulting in unsteady flow dynamics with intensive pressure fluctuations. In particular, swirling flows are organized in combustion chambers to stabilize the flame around the central recirculation zone, formed due to the vortex core breakdown. However, the impact of large-scale vortex structures, including the precessing vortex core and secondary helical vortices, on unsteady combustion regimes is still unclear. The present paper demonstrates experimentally that for the swirling flow of a model swirl combustor, the injection of a central jet may be used to alter the configuration of coherent flow structures, including helical vortices. In particular, the asymmetric hydrodynamics mode, associated with the precessing vortex core, is suppressed, whereas the symmetrical one becomes dominant. This effect demonstrates the importance of central jet injection to control the dominant mode of flow instability for the design of swirl combustors.

Systematic Review: Teknologi Needle Free Jet Injection Insulin (NFJI) Efektif Mengontrol Konsentrasi Glukosa Pada Penderita Diabetes Melitus Tipe 2

Needle-free jet injection (NFJI) is a needleless method for insulin delivery in type 2 diabetes mellitus (T2DM) patients. This study evaluates NFJI's effectiveness in controlling blood glucose. In this study, we conducted a systematic review following the PRISMA guidelines, searching six databases (EBSCO Host, ProQuest, PubMed, ScienceDirect, Scopus, and Web of Science). The search yielded a total of 379 articles. We used the following keywords: "Jet injection," "Injection Ject," "Needle-Free Injection," "Insulin," "Diabetes Mellitus Type 2," "Diabetes Type 2," "Type 2 Diabetes," and "Blood Glucose" to identify relevant studies. The aim was to investigate the effectiveness of insulin jet NFJI in controlling blood glucose levels in T2DM patients. We assessed the risk of bias using the Joanna Briggs Institute (JBI) critical appraisal tools checklist. Out of the 379 articles identified, only seven met the inclusion criteria. Among these, six articles employed the Randomized Controlled Trial (RCT) method, while one article used a quasi-experimental design. Respondents in the study consisted of T2DM patients who were divided into two research groups: the intervention group and the control group. The results indicated a significant difference in blood glucose control values between the two groups. NFJI insulin method significantly improves glucose control. It offers advantages like painless, scar-free, low drug preparation, reusability, ease of use, and minimal disease transmission. Recommended for long-term T2DM treatment.

Bubble fragmentation characteristics during the injection of subcooled water jet into hot liquid pool

Bubble fragmentation and size distribution in hot and cold fluid jet interaction are fundamental for industries such as energy and metallurgy, especially for safety analysis after steam generator tube rupture (SGTR) accidents in lead-cooled fast reactors. The opaqueness to light of the molten lead pool makes it difficult to capture the gas-liquid interface behavior and thus lacks relevant data. In this paper, silicone oil was used instead of lead to simulate the injection process of the SGTR accident. Then the jet visualization experiments were carried out to investigate the bubble fragmentation characteristics. The visualization results show that the jet between the hot and cold fluids process is accompanied by strong thermal interactions, eventually leading to many bubbles dispersed in the high-temperature liquid pool. Secondly, four mechanisms of action affecting bubble size were elaborated in this paper, among which local vapor explosion is the primary mechanism of bubble fragmentation. Finally, the data revealed that bubble size presented a lognormal distribution, and the fragmented bubble size distribution was modeled. This study is promising to provide guidance for the bubble behavior characteristics after SGTR accidents in lead-cooled fast reactors.

Needle-free electronically-controlled jet injector treatment with bleomycin and lidocaine is effective and well-tolerated in patients with recalcitrant keloids.

The treatment of recalcitrant keloids is challenging. Although intralesional bleomycin using conventional needle injectors (CNI) is effective, it has important drawbacks, such as the need for repetitive and painful injections. Therefore, we aimed to evaluate the effectiveness, tolerability and patient satisfaction of intralesional bleomycin with lidocaine administered with a needle-free electronically-controlled pneumatic jet-injector (EPI) in recalcitrant keloids. This retrospective study included patients with recalcitrant keloids who had received three intralesional EPI-assisted treatments with bleomycin and lidocaine. Effectiveness was assessed using the Patient and Observer Scar Assessment Scale (POSAS) at baseline and four to six weeks after the third treatment. Additionally, treatment related pain scores numeric rating scale, adverse effects, patient satisfaction and Global Aesthetic Improvement Scale (GAIS) were assessed. Fifteen patients with a total of >148 recalcitrant keloids were included. The median total POSAS physician- and patient-scores were respectively 40 and 41 at baseline, and reduced with respectively 7 and 6-points at follow-up ( p < 0.001; p < 0.001). The median pain scores during EPI-assisted injections were significantly lower compared to CNI-assistant injections, (2.5 vs. 7.0, respectively ( p < 0.001)). Adverse effects were mild. Overall, patients were "satisfied" or "very satisfied" with the treatments (14/15, 93.3%). The GAIS was "very improved" in one patient, "improved" in nine patients and "unaltered" in four patients. EPI-assisted treatment with bleomycin and lidocaine is an effective, well tolerated, patient-friendly alternative for CNI in patients with recalcitrant keloid scars. Randomized controlled trials are warranted to confirm our findings and improve the clinical management of recalcitrant keloids.

Wind tunnel experimental study of aerodynamic characteristics of co-flow jet wing with built-in air source

To further investigate the aerodynamic characteristics and control mechanisms of co-flow jet wings, this study presents the design of a co-flow jet wing (CFJ-CLARKY18) with an embedded micro centrifugal compressor. The CFJ-CLARKY18 wing, based on the CLARKY18 airfoil, incorporates a miniature centrifugal compressor positioned horizontally within the wing's cavity, with its rotor axis perpendicular to the wing chord line, thus alleviating geometric constraints and the compressor's exhaust swirl. The integration of the co-flow jet device with the wing is achieved through a split-flow channel design to ensure uniform co-flow jet injection, followed by verification of jet uniformity and calibration of six jet momentum coefficients. Subsequently, static and dynamic control experiments of the co-flow jet wing are conducted in an open-return wind tunnel, utilizing force measurement systems and high-speed particle image velocimetry tools to investigate its aerodynamic characteristics and control mechanisms. Static stall tests indicate that, compared to the original wing, the CFJ-CLARKY18 wing exhibits a significant increase in lift and a noticeable delay in stall angle. At low angles of attack, an increase in co-flow jet momentum leads to a reduction in drag coefficient, with the possibility of achieving negative drag (thrust) even at high co-flow jet momentum coefficients. The results of dynamic stall tests with force measurements indicate that, while keeping the reduced frequency constant, an increase in co-flow jet momentum coefficient results in higher maximum lift and average lift coefficients, accompanied by a significant reduction in average drag coefficient and the hysteresis loop area of the lift coefficient. Despite the increased reduced frequency exacerbating the wing's stall effect, the stall effect weakens significantly once the co-flow jet momentum coefficient is increased.

Effect of unsteady supersonic flow on detonation under different hot jet initiation conditions

To understand the actual operation of detonation engines, it is of great significance to simulate the detonation characteristics after being affected by unsteady supersonic flow. Adaptive mesh refinement method and single-step chemical reaction model were used for simulation calculations. The Navier–Stokes equations and hybrid sixth-order weighted essentially non-oscillatory centered difference scheme was adopted in this study. Three different amplitudes of disturbances (0.1, 0.2, and 0.3) and two hot jet injection times were analyzed. The results showed that a moderate disturbance can improve the stability of detonation wave under the ideal hot jet injection time. It allows detonation wave to stay in the combustion chamber for a longer time, which is beneficial for the release of thrust performance. Although the stability of detonation wave is significantly different between the low and high-amplitude disturbances, the residence time of detonation wave is close to the steady flow case under ideal initiation conditions. When the ignition time is insufficient, successful detonation can occur with low and medium-amplitude disturbances. However, the ignition delay was significantly prolonged with medium-amplitude disturbance. There was also greater instability, which is detrimental to the thrust release. When the inflow has a high-amplitude disturbance, the detonation wave fails to ignite due to insufficient energy.

Needle-free electronically controlled jet injection with corticosteroids in recalcitrant keloid scars: a retrospective study and patient survey

First-line treatment of keloids consists of intralesional needle injections with corticosteroids, but generally entails multiple painful sessions, resulting in variable clinical outcomes. Novel needle-free jet injectors may facilitate more effective and patient-friendly dermal drug delivery. Here, we evaluated the effectiveness, tolerability and patient satisfaction of intralesional triamcinolone-acetonide (TCA) treatment in recalcitrant keloids using an electronically controlled pneumatic injector (EPI). A retrospective study was conducted in recalcitrant keloid patients with a history of severe pain during needle injections who received three sessions of EPI + TCA. Outcome measures included Patient and Observer Scar Assessment Scale (POSAS), Global Aesthetic Improvement Scale (GAIS), treatment-related pain (NRS), adverse effects, and patient satisfaction (survey). Ten patients with in total 283 keloids were included. The POSAS score significantly improved at follow-up and GAIS was reported as ‘(very) improved’ for all patients. EPI + TCA was well-tolerated with a significantly lower NRS pain score compared to needle + TCA (pilot treatment). Only minor adverse effects occurred, and 90% of patients preferred EPI over needle treatment. EPI + TCA is an effective and tolerable treatment for patients with recalcitrant keloids. The minimal treatment-related pain and high patient satisfaction makes it a promising treatment for patients with needle-phobia and/or severe pain during needle injections.

Numerical Simulation of the Injection of High-Speed Plasma Jets into a Vacuum

Numerical Simulation of the Injection of High-Speed Plasma Jets into a Vacuum

Effects of inflow velocity on transverse jet injection in a supersonic cavity combustor

The flow, mixing, and combustion mechanisms in the wide range scramjet engine are complex and far from clear. In the present work, the mixing flow of a sonic transverse jet injection in a supersonic cavity combustor is numerically investigated at two typical inflow velocities. The basic flow structures, unsteady flow dynamics, average flow structures, and several significant mixing performance parameters are well captured and compared based on high-resolution large eddy simulation. The simulation results show that separation shock induced by the jet is gradually merged with the bow shock at low Mach inflow so that the curved shock flow patter is produced. In addition, smaller large-scale coherent structures at the windward side and slower large-scale vortex transport are observed at low Mach inflow. At low Mach inflow, moreover, much narrower range of jet species mass fraction distributions and more upstream large-scale vortices breakdown and dissipation can be observed. The low Mach inflow generates weaker pair of counter-rotating vortices and some trailing counter-rotating vortices, which primarily leads to the weaker jet/cavity interaction. The baroclinic term effects are considerably weaker at low Mach inflow in the near field. In view of mixing efficiency and flammability efficiency, the effect of the cavity in enhancing mixing is more evident at low Mach inflow.

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.

Home-Use Hyaluronic Acid Jet Injectors: Unreliable and Unsafe.

Needle-free hyaluronic acid (HA) jet injectors are gaining popularity for rejuvenation treatment. The devices are widely available online and are used for self-injection or in beauty salons by nonphysicians. However, little is known about their performance and safety. To explore the injection efficiency and cutaneous biodistribution patterns administered with home-use compared with medical jet injectors and to assess safety aspects. The authors injected HA into ex vivo human skin with 4 home-use and 2 medical injectors. The intracutaneous dose of HA was calculated, and the cutaneous biodistribution of HA was assessed using a 3-dimensional Fluorescent Imaging Cryomicrotome System (3D-FICS). Safety aspects were evaluated based on the presence of a manual, CE (conformité européenne) mark, and sterility. The intracutaneous dose delivered by the home-use injectors was markedly lower compared with the medical injectors. 3D imaging for home-use injectors showed superficial epidermal distribution with low distribution volumes. For medical injectors, volumes were substantially larger and mainly middermal. All evaluated safety aspects were lacking. Results of this study suggest that the specific combinations of home-use injectors and HA used in this study are unreliable and unsafe, which casts doubts on the performance of these treatments in general.

Spatio-temporal dynamics of an acoustically forced cryogenic coaxial jet injector

This study focuses on the application of dynamical systems theory to characterize the local susceptibility of a nonreacting, cryogenic, coaxial-jet, rocket injector to transverse acoustics. This is achieved using trajectories of the phase space obtained from high-speed imaging data, which reveal the underlying dynamical states of the system. Recurrence analysis is then used to obtain regular patterns in low-dimensional sub-space plots and provide a measure of the local response through recurrence quantification analysis. Of particular interest is quantification of the spatio-temporal coupling of the jet with the external acoustics as a function of the relative momentum flux ratio between the outer and inner jets. At lower outer-to-inner jet momentum flux ratios (J < 1), the jets have a relatively strong local response to acoustic coupling in the near field. This is followed by a sharp drop in this response further downstream where a broad range of instabilities indicates turbulent breakdown of the acoustic mode. This is in contrast to higher outer-to-inner jet momentum flux ratios (J > 1), for which the jets are intermittently coupled to the acoustic mode throughout the entire axial domain due to the presence of a second harmonic or natural instability mode. These dynamical systems analysis tools are used in conjunction with wavelet filtering to improve the utility of high-speed backlit images and are qualitatively consistent with wavelet analysis of the acoustic mode within the flow. The utility of these methods for quantifying the local susceptibility of turbulent coaxial jets to acoustic perturbations can provide powerful insight for the design and optimization of passive or active control systems for bipropellant rocket injectors and other potential propulsion applications.

Improvement of fuel mixing of single ejected 2-lobe fuel injector using shock generator at supersonic flow

In present paper, computational fluid dynamic is applied to evaluate hydrogen mixing impacts of the single extruded lobe injector at supersonic cross flow. The aim of this investigation is to introduce efficient injection system by elongation of the extruded nozzle at high-velocity air flow. The shock waves and temperature contour for the two nozzle heights are compared. The importance of vortex produced inside the domain on the fuel diffusion is also explained. The usage of annular and coaxial air and fuel jet for the improvement of the proposed configurations are also investigated. Obtained results shows that elongation of extruded nozzle form 2 mm to 4 mm improves the fuel mixing about 50%. However, the injection of the inner air jet results in 85% higher fuel mixing in combustion chamber of the scramjet engine.

Effect of water jet area on mitigation of vortex rope in a Francis turbine

The rotating vortex rope (RVR) is normally formed at part load operating conditions, which develops flow instability in the draft tube (DT) cone of a Francis turbine. The detrimental effects of RVR reduce the life and performance of the turbine. The present work mitigates RVR through axial water jet injection in the DT cone. This paper extends the author's previous work on water injection with a 50% reduction in the water jet area through two nozzles with a diameter of 12.7 mm. The effect of area reduction is analyzed by spectral analysis like power spectrum density and spatial harmonic decomposition of the pressure field measured at the wall of the cone. The effect of water jet injection on synchronous and asynchronous pressure pulsations is analyzed at both measurement planes of the cone. The improvement in pressure recovery in the cone and turbine efficiency due to water jet injection is also analyzed. The water is injected at 0.5%–2% of the turbine inlet flow at 22.10° guide vane opening.

Forced Injection of a Spanwise-Inclined Jet in Supersonic Crossflow

Beneficial effects of forced air-jet vortex generators in controlling shock-induced flow separation motivated us to study forced jet injection in detail to understand the advantageous control effects. We performed implicit large-eddy simulations to examine the influence of sinusoidally forced injection of a spanwise-inclined jet in supersonic crossflow. Two forcing frequencies were considered (with and 0.0062) in a crossflow at Mach 2.5 and momentum-thickness Reynolds number of 7000. The underexpansion of the jet has a near-linear dependence on the injection pressure. Consequently, in the near field, the major vortices pulsate with the injection pressure. Statistical analysis using triple decomposition revealed that periodic oscillations of the major counter-rotating vortex pair (CVP) result in momentum transfer by major CVPs, also on their lateral sides, leading to enhanced mixing and lateral spreading, which is beneficial for separation control. Three-dimensional dynamic mode decomposition revealed that forced injection induces a large-scale clockwise rotation of the major vortex. These effects are weak at low forcing frequency. High-frequency jet forcing thus leads to more efficient control of flow separation. On the other hand, periodic oscillations cause these vortical structures to dissipate and breakdown faster in the midfield region than for steady jets. The placement of forced jets is therefore an important parameter when used for separation-control purposes.

Preliminary pharmacokinetics and patient experience of jet-injected dexmedetomidine in healthy adults.

Jet injection is a drug delivery system without a needle. A compressed liquid drug formulation pierces the skin, depositing the drug into the subcutaneous or intramuscular tissues. We investigated the pharmacokinetics and patient experience of dexmedetomidine administered using jet injection in six healthy adult study participants. This needleless jet injection device was used to administer dexmedetomidine 0.5 μg/kg to the subcutaneous tissues overlying the deltoid muscle. Serum concentrations of dexmedetomidine were assayed at approximately 5 minutes, 15 minutes, 30 minutes, 1 hour and 4 hours after administration. Pharmacokinetic interrogation of concentration time profiles estimated an absorption half time for jet-injected dexmedetomidine of 21 minutes (coefficient of variation 69.4%) with a relative bioavailability assumed unity. In our samples the measured median peak (range) concentration was 0.164 μg/l (0.011-0.325 μg/l), observed in the sample taken at a median (range) of 13.5 minutes (11-30 minutes). The Richmond agitation sedation scale was used to assess the sedative effect, and scored 0 (alert and calm) or -1 (drowsy) in all participants. Five of the six participants stated they would prefer jet injection to needle injection in the future and one had no preference. The findings suggest that the use of a larger dose (>2 μg/kg) would be required to achieve the clinically relevant target concentration of 1 μg/l necessary to achieve deeper sedation (Richmond agitation sedation scale ≤3).

Turbulent Eulerian–Eulerian simulation and Taguchi optimization of twin oblique nanofluid jets injecting into a water cross-flow

In this work, a turbulent Eulerian–Eulerian description is utilised to simulate the injection of twin oblique jets of alumina–water nanofluid into a water cross-flow. This technique can be considered as a heat transfer enhancement strategy in cooling technologies. A Taguchi optimization study is undertaken to determine the optimal combination of the involved control factors to achieve the highest heat transfer rate and to explore the contribution ratio of each factor. Inspection of the simulation results demonstrates that about 70% of the contribution on the final response belongs to the velocity and the angle of the first jet. Meanwhile, it is elucidated that the presence of the nanoparticles in the injected jets may not alter the heat transfer rate more than 6%. This indicates that with proper selection of the velocity and the angle of the jets (especially the first one), the need to utilise nanofluids will be eliminated.

Experimental investigation of the optimal driving pressure for a larger-volume controllable jet injection system.

Jet injection technology has become the alternative drug delivery method of conventional needle-based injection due to its obvious advantages. In order to meet the demand for larger volume injection, the pneumatic jet injection systems have efficiently administrated vaccine up to 1mL in human. Our recent study has also demonstrated that controlling the driving pressure enabled the pneumatic jet injection system to deliver larger volumes of drugs to target sites at desired rates and times. This work continues to explore the optimal two-phase driving pressure combination with better injection efficiency for typical larger-volume (1.0mL) jet injection with controllable pneumatic jet injection system. Under the combination of a first phase driving pressure of 1.00MPa and a second phase driving pressure ranging from 0.25 to 0.90MPa, dynamic characteristics, dispersion characteristics and pharmacokinetic characteristics of this controllable jet injection system were quantitatively analyzed. In all experiments, it was confirmed that the optimal driving pressure combination of 1.0mL ejection volume was close to (1.00-0.50) MPa. That is, the injection velocities of 151.85m/s and 102.01m/s for the first and second phase respectively facilitated better injection performance with a controlled release of 1.0mL ejection volume. This strategy is practical for facilitating the clinical application of large-volume controllable jet injection systems.

Computational analysis of influence of CFJ components on aerodynamic performance

This research aims to explore the effect of the co-flow jet (CFJ) airfoil injection jet velocity, injection height, and injection mass flow rate on the aerodynamic coefficient through numerical analysis. Five distinct circumstances are generated by adjusting the jet velocity, injection height, and mass flow rate, and each of the cases underwent numerical investigation. For this computational analysis, Reynolds averaged Navier–Stokes (RANS) solver has been utilized by employing the Spalart–Allmaras turbulence model, and the flow is treated as incompressible. The higher injection slots reduce the coefficient of lift (CL) due to poor aerodynamic shape, which can be overcome by injecting higher jet velocities, whereas lower jet velocities injecting into lower injection slots do not raise the CL even though they have streamlined aerodynamic shape. Hence, even if CFJ airfoils with poor geometry perform less aerodynamically, this problem is not intractable because it can be solved by injecting high jet velocities; meanwhile, injecting low velocities will result in reduced aerodynamic performance for CFJ airfoils with good geometry. The CFJ airfoil with the highest jet velocity and lowest injection slot increases the CL by a maximum of 65% compared to the baseline airfoil, which is higher than all other CFJ airfoils taken into consideration.

Application of Shadow Visualization to Study the Drag of Toroidal Bubbles

In this work, the ascent of a toroidal bubble created by the injection of a pulsed air jet into water vertically upwards is studied by the shadow method. When using the shadow method, the bubble border on the image is darkened, and the contrast in comparison with the background is increased, which makes it possible to use software processing algorithms to determine the parameters of the ring on each frame. There are experimental results indicating that, in addition to the buoyancy force, the drag force also acts on the toroidal bubble. In this paper, the experimental data on the change in the torus radius as a function of time are compared with a theoretical model constructed with and without taking into account the drag force. It is shown that taking into account the drag force leads to a much better agreement between theory and experiment. The drag force is concluded to act on toroidal bubbles, but its influence decreases with time, i.e., as the bubble rises. The drag coefficient used in the calculations is determined empirically and assumed to be constant.