Air Injection Research Articles

Multiphase Flow Simulations to Explore Novel Technique of Air Injection to Mitigate Silt Erosion in Hydro Turbines

Multiphase Flow Simulations to Explore Novel Technique of Air Injection to Mitigate Silt Erosion in Hydro Turbines

Cerebral air embolism after accidental air injection into a radial artery sheath.

Cerebral air embolism after accidental air injection into a radial artery sheath.

A North Pacific Meridional Section (U.S. GEOTRACES GP15) of Helium Isotopes and Noble Gases II: Shallow Distributions

AbstractThe distribution of helium isotopes in the upper kilometer of the water column along the GP15 section in the central Pacific reflects the large‐scale patterns of upwelling hydrothermal 3He in the tropics and sub‐polar gyre, tracing two important pathways whereby bottom water exits from the deep Pacific. Heavy noble gas saturation anomalies, particularly in the upper two hundred meters of the water column, are more strongly increased by seasonal radiative heating, while lighter noble gas saturation anomalies are increased more by air injection processes. A similar, seasonally persistent radiative heating feature was observed in the Equatorial Undercurrent, and appears to be replicated in climate system model simulations. The origin of this feature, however, remains a mystery. A heuristic component model explains the noble gas saturation anomaly distributions, separating the influences of air injection, barometric pressure and radiative heating/cooling. Results show cohesive spatial patterns consistent with where water masses originate, their circulation, and gas exchange dynamics in relation to their formation regions. Using this model, we diagnose the distribution of “non‐atmospheric” 4He in shallow waters, which parallels the helium isotope anomaly and silica distributions.

Cardiac Lymph Flow Features and New Opportunities for Their Experimental Visualization.

The aim of this study was to describe the features of myocardial lymph flow using a new combined method of visualization of the lymphatic system. The study was performed on pig hearts harvested from a local slaughterhouse. The original dye, consisting of lipid-soluble chlorophyll and lipiodol, was injected stepwise into the lymphatic vessels. After sufficient optical identification of the lymphatic vessels, continuous injection of air into the coronary arteries was performed and CT scans were done. In this way, both optical and radiologic visibility of the cardiac lymphatic system was achieved. It was shown that lymph flow of the left and most part of the right ventricle is carried out through lymphatic collectors of the anterior wall of the heart, including retrogradely with respect to the right coronary artery, which complements the previously known facts about the structure of the lymphatic system of the heart.

Effect of intracameral air injection during Ahmed glaucoma valve implantation on hypertensive phase

The purpose of this study was to evaluate the difference in the incidence of the hypertensive phase (HP) between Ahmed glaucoma valve (AGV) patients who received intracameral air injection and those who did not. A total of 78 patients who underwent AGV surgery between January 1, 2016 and June 30, 2023 were included in this retrospective study. HP was defined as intraocular pressure (IOP) greater than 21 mmHg within the first 6 postoperative months. Among baseline characteristics, except for neovascular glaucoma and baseline IOP, there were no differences between the air injection and control groups. In the air injection group, the rate of HP was 19%, which was significantly lower than 49.1% in the control group (p = 0.017). In multivariate logistic regression analysis, baseline IOP had a significant positive correlation (OR: 1.120, p = 0.026), while age and intracameral air injection had a significant negative correlation with the incidence of HP (OR: 0.938, p = 0.028, OR: 0.142, p = 0.029). Postoperative IOP at 1 year and surgical success rates were not different between the two groups. Intracameral air injection during AGV surgery can significantly reduce the risk of HP. Intracameral air injection can be a simple procedure in AGV surgery for reducing HP.

Viscous fingering and interface splitting instabilities in air-water-oil systems.

Viscous fingering instabilities of air displacing water displacing mineral oil is controlled by the air injection rate. Given the lower viscosity of the water, air would tend to finger through the water and then after it reaches the oil, proceed to finger through the oil. In a radial Hele-Shaw cell, experiments were conducted on air injection into mineral oil and air injection into a volume of water at the center of the cell which in turn is surrounded by mineral oil. The images of the fingers are analyzed to quantify the fingering patterns to compare the behaviours between the two and three phase systems. Significantly different fingering patterns occur between the two and three phase systems. When air fingers penetrate the water layer and reach the oil, the air propagates along the interface between water and oil in an interface splitting instability mode resulting in development of more intricate fingering patterns. It was also observed that air fingers penetrate within water fingers that penetrate the oil. In addition, the fingertip moves faster with the presence of water exhibiting a discontinuity of the fingertip velocities across the water and mineral oil regions.

Effect of Anterior Chamber Air Injection on Intraocular Lens Stability after Phacovitrectomy with Gas/Air Tamponade

Purpose: Anterior chamber air injection (ACAI) is a surgical technique used to decrease the occurrence of postoperative intraocular lens (IOL) haptic dislocation following phacovitrectomy with gas/air tamponade. The impact of this technique on IOL stability remains uncertain, prompting the design of this study to investigate further. Methods: This study included 51 eyes of 51 patients who underwent phacovitrectomy with gas/air tamponade. The patients were divided into two groups: Group 1 (ACAI group, 26 eyes) and Group 2 (non-ACAI group, 25 eyes). IOL position (IOLP) is used to determine the IOL axial movement. The study analyzed changes in lens/IOL decentration, tilt, and aqueous depth (AQD) using repeated measures analysis of variance. The linear regression model was employed to investigate the factors influencing the IOL stability. Results: There was no significant difference in IOL decentration, tilt, mean prediction error, and mean absolute error between the two groups. ACAI not only caused the IOLP to move axially forward but also the AQD to take longer to stabilize. Preoperative lens tilt is a significant factor influencing postoperative IOL tilt. Additionally, sex, ACAI, and aqueous width are identified as factors that affect IOLP. Conclusion: ACAI is a factor that can affect IOL instability, and the surgeon needs to consider the necessity of ACAI when performing phacovitrectomy with gas/air tamponade.

Effect of air injection on flow characteristics of submerged wall jets and scour mitigation downstream of apron

The local scour downstream of a rigid apron, caused by submerged wall jets from sluice gate openings, is critically important as it poses a significant threat to structural stability. This study examines the impact of air injection at the apron's end on flow structures and scour mitigation under a wall jet flow. We have expanded the coupled model between Large Eddy Simulation and the Discrete Element Method from our previous study, using the open-source package OpenFOAM, incorporating the Volume of Fluid method to apply it to air injection and free surface. Validation of the numerical model shows a good agreement between the simulation results and observed data, confirming the model's reliability. The model was subsequently used to investigate the effects of varying air injection flow rate on flow structures and scouring processes downstream of the apron by increasing the flow rate ratio of air injection to water wall jet from 0 to 1 at the end of the apron. The simulation results reveal that as the flow rate ratio increases, the near-bed streamwise mean velocity, streamwise turbulence intensity, and bed shear stress are decreased downstream of the apron. Consequently, as the air injection flow rate ratio increases, the bedload transport rate decreases, and scour is further mitigated. However, when the air injection ratio exceeds 0.6, no notable differences in the flow properties are observed and the bed profile therefore remains almost unchanged. This is attributed to the strong air injection deflecting the wall jet upwards, preventing it from affecting the downstream area of the apron. The numerical analysis demonstrated the effects of air injection on flow structures, which consequently mitigated scour processes. The key finding of this study is that air injection can effectively reduce scour processes downstream of the apron, offering improved design methods to protect hydraulic structures compared to traditional countermeasures.

Submacular hemorrhage displacement with subretinal rtPA and air injection

Aims/Purpose: submacular hemorrhage (SMH) is a well‐known cause of severe vision loss. Surgical treatment aims displacement of the blood away from the fovea to prevent macular photoreceptor damage. Different surgical techniques have been described for this purpose, but, until date, the best approach remains a matter of debate. Injection of subretinal rtPA and air was first described in 2013 reporting encouraging results. We describe our experience with this surgical technique.Methods: consecutive case series including patients with SMH managed with PPV and subretinal injection of rtPA and air. SMH was graded as small, large, extensive, or massive. SMH displacement was assessed one week after surgery.Results: 36 eyes of 36 patients were evaluated. Etiologies of SMH included age‐related macular degeneration (83.3%), macroaneurysm rupture (8.3%), ocular traumatism (5.6%) and Terson syndrome (2.8%). Average time between diagnosis and surgical intervention was 6.1 days. Hemorrhage size was classified as small in 8 patients (22.2%), large in 8 patients (22.2%), extensive in 16 patients (44.4%) and massive in 4 patients (11.1%). Sub‐RPE hemorrhage was noticed in 21 patients (58.3%). One week after surgery, SMH displacement was achieved in 33 patients (91.7%). Visual acuity improved in 28 patients (77.8%), remained stable in 4 patients (11.1%) and worsened in 4 patients (11.1%). Postoperative complications included vitreous hemorrhage (11.1%), macular hole (5.6%), and retinal detachment (5.6%).Conclusions: subretinal injection of air and rtPA is an effective technique for SMH displacement, facilitating rapid blood migration and, thus, reducing retinal deterioration and enabling greater visual recovery.References Martel JN, Mahmoud TH. Subretinal pneumatic displacement of subretinal hemorrhage. JAMA Ophthalmol. 2013; 131: 1632–5.

Enhancing wastewater treatment efficiency through hydrodynamic cavitation and advanced oxidation processes: Experimental insights and comparative analysis

Enhancing wastewater treatment efficiency through hydrodynamic cavitation and advanced oxidation processes: Experimental insights and comparative analysis

A Retrospective Analysis of the Efficacy of Anterior Chamber Air Injection for Post-Cataract Surgery Descemet’s Membrane Detachment

A Retrospective Analysis of the Efficacy of Anterior Chamber Air Injection for Post-Cataract Surgery Descemet’s Membrane Detachment

Enhancing in-situ air injection conversion: catalytic roles of metal oxides in kerogen-rich shale oxidation

Enhancing in-situ air injection conversion: catalytic roles of metal oxides in kerogen-rich shale oxidation

Air injection in Subsurface Drip Irrigation as an Efficient Method for Zucchini Production

Agriculture is a key pillar of the economy, constantly facing challenges due to population growth and climate change. Enhancing the sustainability and efficiency of crop production and improving water use efficiency are essential. to evaluate air injection into subsurface drip irrigation system for zucchini production as efficient method for subsurface drip irrigation systems to improve water use efficiency (WUE), and zucchini production in heavy clay soils. Results showed that injecting air through built-in emitters using a compressor during the last third of the irrigation time maintained acceptable system performance, as measured by indicators like CV, qvar, and EU%. It also improved the physical properties of dry sieved aggregates and enhanced the availability of macronutrients, significantly improving and maintaining heavy clay soil, leading to a 27% increase in zucchini crop yields and 22% water savings compared to the control. Economic analysis indicated that air injection was a feasible option, increasing gross returns by 21% compared to the control, with a benefit-cost ratio of 2.3% for air injection versus 1.8% for the control.

Optimization of Flotation Efficiency of Micro Bubbles Using Low-Energy Best Available Technique

Global warming caused by urbanization, industrialization, and population growth is leading to climate change and threatening our sustainable lives. As a response to this climate crisis, a best available technique(BAT) that minimizes the emission of existing pollutants and is also economical is required. The purpose of this study is to develop a lowenergy micro bubble generator to reduce energy consumption in water treatment facilities and to evaluate its performance in comparison with dissolved air flotation(DAF) and coagulation-flocculation processes. The low-energy micro bubble generator consists of an air injector, a chamber, and a nozzle. The experimental results showed that the low-energy micro bubble generator generated micro bubbles of similar size to DAF at an air injection rate of 5 ml/min. In addition, the flocculant concentration experiments showed that the low-energy micro bubble generator had 1.3-2.5 times higher turbidity removal efficiency than DAF and coagulation-flocculation processes even with flocculant injection of 8 mg/L or less. These results suggest that the low-energy micro bubble generator is effective in removing suspended solids from water and is an optimal solution for reducing carbon emissions. This study is expected to contribute to the increased utilization of this technology in industrial sites.

A Review of Stall Detection in Subsonic Axial Compressors

Stall events in axial compressor systems have been a limiting factor for efficiency of such systems and a source of safety concerns. The detection of the onset of stall, and in many cases the precursor of the onset of stall, have been of interest in the axial compressor community for many decades. As such, development of algorithms along with active control could lower cost, reduce emissions, improve safety, and increase market competitiveness. To gain an understanding of these stall phenomena, past and current research has focused on modeling axial compressors as dynamic systems, with a focus on obtaining descriptive formulations of the physical aspects of stall. Some of these approaches allow for active control measures that extend the stall margin of the compressor system to increase safety and efficacy. This paper reviews the major contributions in these listed pursuits and presents the latest methods and algorithms for stall precursor detection in low-speed axial compressors. In particular, a review is presented in the types and characteristics of stalls, the major mathematical models used to describe these systems, influences of physical attributes such as tip clearance, guide vanes, and groove casing—operating as passive control elements—but also active control utilities such as air injection are discussed along with a detailed review of existing stall precursor detection algorithms. In addition, a forward-looking projection is presented that includes the use of machine learning algorithms to further the understanding and the capability of stall precursor detection.

Prefabricated vertical drain alleviating clogging mechanism of soft ground by air-boosted vacuum preloading method

The prefabricated vertical drain (PVD) alleviating clogging mechanism under different air injection pressure and time is not clear for air-boosted vacuum preloading. The computational fluid dynamic-discrete element method (CFD-DEM) is developed to dynamically observe PVD clogging and investigate the PVD clogging mechanism. i.e., PVD discharge rate, soil particle migration, and porosity change under the different air injection patterns of vacuum preloading with no air injection, constant air injection pressure of 75 kPa, and variable air injection pressure of 25∼150 kPa. Compared with conventional vacuum preloading with no air injection, the water discharge rate of PVD can be increased, clogging layer area can be reduced significantly for air-boosted vacuum preloading. The porosity near the air injection port is greater than that close to the PVD. The consolidation mechanism of air-boosted vacuum preloading the disturbance effect in the early stage of consolidation, the pressurization effect in the middle stage of consolidation, and the clogging effect in the later stage of consolidation are revealed. Three kinds of laboratory model tests are run to demonstrate air injection alleviating PVD clogging. The results demonstrate that increasing the air injection pressure can significantly alleviate PVD clogging.

Injection Of air control of propeller performance

With the rise of bubble lubrication technology in transport ships, the interaction between propellers and bubble flow has become increasingly important. On the basis of solving the Reynolds averaged equation and the volume fraction equation, a numerical model of the propeller in a water air mixed fluid was established using the sliding mesh technique. Based on verifying the numerical calculation model of the semi-immersed propeller, uncertainty analysis was conducted on the KP505 propeller flow numerical model, and the open water performance of the propeller was calculated to be affected by the injection position and injection volume. A linear model was established to describe the relationship between the open water performance of the propeller at the axis and the injection rate. The performance surface model was used to describe the effect of the air injection position moving towards the blade tip on open water performance at different air injection rates. The strength and dissipation of the tip vortex and hub vortex of propeller are affected by the radial air injection position. Air injection at the axis causes the hub vortex to expand and connects the tip vortex to form a vortex ring in the far field. The air injection position moves towards the blade tip, and the vortex system at the blade tip accelerates and rapidly dissipates.

Hydroxyl Radicals Production in Nitrogen Fixation with Addition of Fe2+ Ions Using Plasma Electrolysis

Nitrogen fixation using the Haber-Bosch process generates carbon dioxide emissions, so environmentally friendly alternative technologies are needed. Plasma electrolysis is recommended as a nitrogen fixation method that produces liquid nitrate because it does not generate emissions with raw materials from the natural air. The plasma electrolysis process generates hydroxyl radicals in the nitrate formation process. Thus, the aim of this research is to increase hydroxyl radicals by adding Fe2+ ions. The methods used include characterizing the current and voltage strength in the reactor to observe the glow discharge position for plasma formation. The analysis of hydroxyl radicals formed with the addition of Fe2+ ions was conducted using Electron Spin Resonance (ESR). The analysis of the yield of liquid nitrate formed was performed using a UV VIS Spectrophotometer. The results obtained were the emission spectrum of radicals formed in plasma without air injection. The wavelengths of the detected radicals are as follows: •OH (hydroxyl radical) at 306 nm, with an intensity of 21.696 a.u, •H (hydrogen radical) at 654 nm, with an intensity of 12.572 a.u. and •O (oxygen radical) at 844 nm, with an intensity of 13.267 a.u. When air injection is used, 0.8 liters per minute (lpm), there is a significant increase in the intensity of reactive species required for nitrate formation, such as excited nitrogen (N₂*) at 28540 a.u, hydroxyl radicals (•OH) at 30863 a.u, and oxygen (•O) at 49800 a.u. the concentration of nitrate produced reaches 1889 ppm. This is different from the condition without air injection (0 lpm), where nitrate is not formed.

Substantiation of Drying Modes for a New Universal Method of Short Flax Fiber Drying

Deep processing enterprises often receive short flax fibers with high moisture content, which must be dried to meet processing requirements. (Research purpose) To investigate the effect of process parameters (speed, drying agent consumption, air injection and vacuum, air temperature in the drying chamber) on the drying time of short and uniform flax fibers. (Materials and methods) The studies were conducted using a new drying unit with air recirculation. Flax fibers were pre-moistened to a moisture content of 35-40 percent and loaded into the working chamber. Before drying, and then at one-minute intervals during the process, the fibers were weighed to monitor moisture loss. Additionally, the air temperature at the inlet and the outlet of the drying chamber, as well as in the mixing chamber, was measured before the start of the process and then at one-minute intervals. Experiments were conducted using various combinations of speed and flow rates for both incoming and outgoing air in the drying chamber. The initial temperature of the drying agent was 70-80 degrees Celsius, with a relative humidity of 5 percent. The average ambient temperature in the facility was 17 degrees Celsius, and the recirculation degree was 1.4. (Results and discussion) The drying duration of short flax fibers from a moisture of 30 to 14 percent is 1.3-1.9 minutes. Switching the airflow mode from injection to vacuum does not significantly affect the drying time; for effective drying, an air speed of 8-9 meters per second should be maintained. The temperature of the drying agent continuously increases, while the exhaust air temperature initially drops by 25-28 degrees Celsius before rising again. The temperature of the mixed air remains almost unchanged. (Conclusions) For the first time, optimal process parameters have been determined for drying short flax fibers in a new installation with air recirculation: a drying duration of 1.3-1.4 minutes, a drying agent temperature of 75-80 degrees Celsius, as well as ideal combinations of airflow rate and speed for both the incoming and outgoing air.

A Parametric Study on Air Lubrication for Ship Energy Efficiency

With the new target set by the International Maritime Organization (IMO) of zero net emissions of atmospheric gases from maritime vessels by 2050, studies of methods that improve the efficiency of vessels have become highly relevant. One promising method is air injection, which creates a lubricating film between the hull and water, reducing the total resistance. Despite the potential of air injection, there is a lack of studies defining the correlation between key parameters (such as air layer thickness, injection angle, vessel speed, and the number of nozzles) in the method efficiency. Therefore, this study aimed to assess the method’s efficiency through a parametric analysis. The study utilized the OpenFOAM software to analyze the air injection method in the Duisburg Test Case (DTC) hull, a 1:59 scaled container ship. The numerical solution used finite volumes to discretize the conservation equations, RANS (Reynolds-Averaged Navier–Stokes) in the momentum equation, and κ-ω SST in the turbulence model. The optimum configuration achieved 14.13% net power savings, while the worst configuration increased the power consumption instead. An analysis of variance (ANOVA) confirmed the relationship between parameters and effectiveness. Therefore, the results showed the importance of adjusting the method’s parameters.