Nozzle Depth Research Articles

Continuous Casting Slab Mold: Key Role of Nozzle Immersion Depth.

Based on a physical water model with a scaling factor of 0.5 and a coupled flow-heat transfer-solidification numerical model, this study investigates the influence of the submerged entry nozzle (SEN) depth on the mold surface behavior, slag entrapment, internal flow field, temperature distribution, and initial solidification behavior in slab casting. The results indicate that when the SEN depth is too shallow (80 mm), the slag layer on the narrow face is thin, leading to slag entrapment. Within a certain range of SEN depths (less than 170 mm), increasing the SEN depth reduces the impact on the mold walls, shortening the "plateau period" of stagnated growth on the narrow face shell. This allows the upper recirculation flow to develop more fully, resulting in an increase in the surface flow velocity and an expansion in the high-temperature region near the meniscus, which promotes uniform slag melting but also heightens the risk of slag entrainment due to shear stress at the liquid surface (with 110 mm being the most stable condition). As the SEN depth continues to increase, the surface flow velocity gradually decreases, and the maximum fluctuation in the liquid surface diminishes, while the full development of the upper recirculation zone leads to a higher and more uniform meniscus temperature. This suggests that in practical production, it is advisable to avoid this critical SEN depth. Instead, the immersion depth should be controlled at a slightly shallower position (around 110 mm) or a deeper position (around 190 mm).

Physical modeling and numerical investigation of fluid flow and solidification behavior in a slab caster mold using hexa‐furcated nozzle

AbstractSlag entrapment from metal–slag interface during continuous casting operations has been a major area of concern for steelmakers globally. The presence of inactive regions in the upper region of the mold poses another challenge. Proper flow behavior of the molten metal coming out of the nozzle in the mold is required to overcome these challenges. Nozzle design greatly affects the flow pattern of the molten steel inside the mold. The present investigation is an attempt to study the flow and solidification behavior in a slab caster mold with the use of a novel‐designed hexa‐furcated nozzle using numerical investigation results. The casting speed and submerged entry nozzle (SEN) depth are varied to study the effect of these parameters on minimizing the inactive zones in the mold and the steel/slag interface fluctuations. The results show that the interface fluctuation increases at higher casting speed and lower SEN depth. The residence time distribution (RTD) analysis was also performed for different cases to investigate the flow behavior. The validation of the fluid flow and RTD curve inside the computational domain is carried out with the use of physical modeling.

Degassing Dissolved Oxygen through Bubbling: The Contribution and Control of Vapor Bubbles

An innovative yet sustainable approach for industrial deaeration is proposed, with demonstrated results and analyses, to contribute to finding solutions to improve energy efficiency in this field. Vacuum bubbling deaeration, sharing the same working principles of solubility control and the mass diffusion through vapor (or steam) with conventional thermal deaeration processes, works, however, at lower vacuum pressures. It neither resorts to heating nor requires any third-party materials such as membranes or gases, achieving orders of magnitude of reduction in the expected energy consumption in a simple and concrete way. In this study, the mechanisms of vapor bubble generation and retention were discussed by employing a vacuum bubbling model based on the experimental apparatus at Kongju National University, which uses a venturi-nozzle bubbler. The four parameters influencing vapor bubble generation and retention were identified as vessel pressure p1, nozzle depth Δh, nozzle performance p4−p3, and water temperature Tw. A series of deaeration experiments using the present approach for a tap water sample of 360~400 L were conducted under four different conditions to investigate the effects of the water temperature, vessel pressure, and bubbler nozzle depth. Final dissolved oxygen (DO) concentrations close to zero could be achieved with a vessel pressure of p1=1 kPa, with different bubbling times to reach a zero mg/L reading of DO concentration (case 2 and 3), which demonstrates the vital roles of the vapor bubble generation condition of (psat−p3) and retention condition of (p4−psat) in achieving the lowest DO concentration. Analysis of the test results, based on the discrete-bubble model with the measured DO concentrations and degassing rates, showed promising results in reproducing the experimental data. Though the potential of vacuum bubbling deaeration is demonstrated, for the first time, to its full extent, further research efforts are encouraged in many areas, including more case-specific validation test cases with optimum operating conditions along with the study of more detailed modeling for performance prediction, including energy analysis.

Nasal steroid spray simulations using measured spray characteristics in healthy and rhinitic nasal passages

Intranasal corticosteroid sprays (ICSs) are frequently prescribed for allergic rhinitis (AR), which is the fifth most common chronic disease in the United States. This study aimed to investigate how the intranasal distribution of ICSs is affected by spray characteristics, patient use factors, and anatomical variation. Three-dimensional reconstructions of the nasal cavity were created from computed tomography (CT) scans of one healthy subject and one AR patient. A virtual spray nozzle was positioned in the nasal vestibule according to package insert instructions and subtracted from the nasal airspace. Hybrid tetrahedral-prism meshes were created and spray simulations were conducted in ANSYS Fluent™ with inspiratory airflow present and spray characteristics from in vitro experiments. Changes in regional corticosteroid deposition with variations in spray product, actuation force, inhalation rate, spray cone angle, nozzle insertion depth, nozzle position, and nasal side were assessed. The simulation results demonstrated that, in both models, target site deposition was mostly affected by changes in nozzle position and anatomy (left vs. right nostril). In the healthy subject, target site deposition increased with a higher actuation force, higher inhalation rate, and smaller nozzle depth, but was not significantly affected by changes in the spray cone angle. In the AR patient, target site deposition was not significantly different for changes in actuation force, inhalation rate, nozzle depth, or cone angle. The findings of this numerical study suggest that the intranasal distribution of ICSs is influenced mostly by nozzle position and nasal anatomy.

Application of Electromagnetic Braking to Minimize a Surface Wave in a Continuous Caster.

The turbulent flow in the mold region drastically influences the quality of steel produced during continuous casting. The flow itself can lead to surface defects or slag entrainment based on the formation. A high surface wave can lead to fluctuations and the instability compromises the quality of the steel produced, as well as entrain the slag. To regulate the flow, electromagnetic forces can be applied in the mold, dampening the local turbulent flow. As the electrically conductive molten steel interacts with the induced magnetic field, it reduces the velocity of the steel jet released from the ports of the submerged entry nozzle. Utilizing Star-CCM+, a simulation-based study is conducted modeling the impact of Electromagnetic braking (EMBr) on the flow formation and surface standing wave. Specifically, a parametric study is conducted investigating the impact of submergence entry nozzle (SEN) depth and mold width with applied EMBr. Per the simulation-based study conducted increasing the EMBr strength from 2975 G to 4350 G reduced the average surface wave height by 12.5% and volume of flux rate of decrease by 4.25%. Additionally, increasing the SEN depth from 110 mm to 350 mm increased the average wave height by 19% and volume of flux rate of decrease by 2.6%. Lastly, increasing the mold width from 1.067 m to 1.50 m increased average wave height by 8.71% and volume of flux rate of decrease by 0.9%.

Influences of the Braking Effect of Ruler EMBr on Molten Steel Flow and Steel–Slag Interface Fluctuation in a Continuous Casting Mold

Electromagnetic braking (EMBr) technology, as one of the most effective technologies in the continuous casting process, provides an effective tool for improving the internal and external defects of steel products. Specifically, the EMBr technology takes the benefit of the generation of Lorentz force to decrease flow instability, mold powder entrapment, and surface defects, if applied properly. For this purpose, to gain a clear understanding of the effect of EMBr technology on the continuous casting process, a commonly used EMBr technology, namely ruler EMBr technology, is applied in the current work to investigate the dynamic behaviors of molten steel flow and steel–slag interface fluctuation inside a slab mold. Furthermore, to obtain a desirable braking effect of the ruler EMBr technology, operational parameters including the magnetic flux density, submerged entry nozzle (SEN) depth, and magnetic pole location are numerically investigated. The results demonstrate that the braking effect exerted by the ruler EMBr device is favorable for suppressing the impact of upward stream on the steel–slag interface with the magnetic flux density exceeding 0.3 T. For the influence of the SEN depth and magnetic pole location on the effect of ruler EMBr mold, the results show that a steady jet flow pattern can be obtained through the adjustment of a location between the ruler EMBr device and the SEN depth. For instance, when the ruler EMBr device installation position of 225 mm corresponds to the SEN depth of 150 mm, the upward deflection of jet stream is suppressed and a stable interface fluctuation profile is formed. With this adjustment, the possibility of mold flux entrapment is decreased.

Design and Test of a Riding Pontoon Hydraulic Lotus Root Digging Machine

In order to solve the problem of high labor intensity of a traditional pontoon lotus root machine with manual pushing operation, a riding pontoon digging lotus root machine was proposed in this paper. The working principle of the digging machine was introduced, the key components were designed, and the buoyancy of the pontoon was calculated and analyzed. The performance of the digging machine was tested in a lotus root pond, the lotus root digging rate was 76%, and hydraulic flushing generated by the digging machine can disperse the soil within 30 cm under water. In addition, the best flushing effect was achieved when the number of working nozzles was controlled to three. Finally, according to the test results, the optimization measures of the hydraulic lotus root digging machine were proposed, and the CFD-DEM coupled simulation model was used to simulate and analyze the soil disturbance effect of hydraulic flushing upward from the bottom of the lotus root. The results showed the relationship between nozzle diameter, angle and hydraulic flushing depth. When the nozzle angle was fixed, the soil disturbance effect decreased with increasing flushing depth and increased with decreasing nozzle diameter. When the nozzle depth was fixed, both the diameter and the angle had a significant effect on the soil disturbance effect. When the nozzle diameter was fixed, the interaction of angle and depth had no significant effect on the soil disturbance effect.

Investigation of Diesel Engine Combustion Characteristics for Varying Nozzle Depth at Different Spray Angles

The demand for petroleum-derived fuels is increasing every day despite their speculations about the exhaustion of petroleum fuel. Petroleum-derived fuels are classified as a suspect element for humans due to their known primary adverse effects on the environment. The concern is that the demand for petroleum fuel will rise along with the market price. Researchers around the world focus on reducing the harmful effects of petroleum fuel or finding some other substitute for petroleum fuels. A Kirloskar single cylinder diesel engine (model TV-1) was selected for simulation using commercially available AVL FIRE software. The published articles indicate the operating conditions and limitations of the single cylinder diesel engine. The geometry of the hemispherical cup piston is generated and networked in software, then the search is processed by selecting three different spray angles, such as 120o, 140o, and 160o. The standard spray angle is 120o. In addition, four nozzle depths are included in the search to analyze the effect of nozzle depth on combustion parameters. The nozzles are available in four depths: 0.5 mm, 1 mm, 1.5 mm, and 2 mm. while the nozzle depth is 1 mm standard nozzle depth. Four nozzle depths with spray angles of 120°, 140°, and 160° are examined. The results returned the combustion parameter and depend on the spray angle and the depth of the nozzle. To obtain an adequate combustion result from the above scenario, some trade-offs in terms of combustion parameters need to be considered.

The effect of rangeland quality on the mohair quality of Angora goats fed on the natural rangelands

The aim of this study is to determine the effect of the rangeland quality of Ankara goats fed on some natural rangeland in Ankara on the mohair quality. The research was carried out in 3 different quality natural rangelands in Ankara province. Crude protein, ether extract, Ca, Fe, N, energy contents and digestibility, in vitro gas production, and relative feed values of good quality rangeland plants were the highest compared to other rangelands, but the crude fiber, acid detergent fiber, and neutral detergent fiber were the lowest (p < 0.05). In the study were used a total of 120 animals (20 males, 20 females in each farm) from 3 farms where Angora goats are raised in the region of rangelands. The mohair quality was determined in mohair samples taken from 6 month old, 1.5, and 2.5-yearold animals. Rangeland quality significantly affected mohair lengths, fineness, elasticity, tenacity, and clean mohair yield, in males and females (p < 0.05). The highest values were obtained from goats fed good quality rangeland (p < 0.05). The effect of age on these features was also important. The mohair quality (length, elasticity, tenacity) increased with increasing age (p < 0.05). The effect of the rangeland quality on the nozzle number was not significant, but the effect of age was significant. and, the nozzles number increased with increasing age. The nozzle depth was affected by the rangeland quality and age. The nozzle depth has increased due to the increase in rangeland quality and age. While the mohair Ca, Mg, S, Fe, and N content of male and female goats were higher in goats fed on good quality rangeland, these were lower in goats fed low-quality rangeland (p < 0.05). While mohair Na content positively affected rangeland quality in females (p < 0.01), was insignificant in males.

Influence of the presence of a “shelf” on the outer surface of the submerged nozzle and the electromagnetic effect within its length on the qualitative distribution of metal flows during continuous casting of steel

Continuous casting of steel has many ways to control the quality of the billets. The possibilities offered by electromagnetic stirring are far superior to physical eff ects, but combining these two quality control methods can be extremely effective. Research have shown the possibility of a qualitative effect on the flow of the liquid in the mold with implementation of electromagnetic stirring technology and the “skirt” is used in the form of a “shelf” on the nozzle, which is immersed in the mold. In addition, implementation of this shelf increase the possibilities of using direct-flow nozzles with the slope of the inner wall, where in each case it gives advantages, both with an expanding channel, and with a narrowing one. The design of the shelf also does not affect the implementation of electromagnetic stirring in the process of continuous casting, since it is below the level of the mold meniscus and above the level of the effect of the electromagnetic stirrer in the mold. The results of the research show that when using a “shelf” in the middle of the immersion nozzle depth, the casting process is accompanied by the control of most of the flows that are created when the jet enters into the mold and effect of EMS. It also affects the formation of vertex on the meniscus. And the implementation of a “shelf” at the outlet of the submersible nozzle completely changes the nature of the flow of the incoming jet.

Emission Characteristics of Single Cylinder CI Engine for Varying Nozzle Depth at Different Spray Angles

The present research is about the reduction of harmful gases from the exhaust of a diesel fuel operated diesel engine. A kirloskar single cylinder diesel engine (model –TV-1) is selected for the numerical simulation using commercially available software AVL FIRE. The operating and boundary condition of single cylinder diesel engine is referenced in the published articles. The hemispherical bowl piston geometry is generated and meshed in the software the research is further processed with the selection of three different spray angles like 120o , 140o , and 160o . Whereas 120 spray angle is the standard spray angle. Additionally to analyzed the effect of nozzle depth on the emission, combustion and performance parameters four nozzle depth values are also included in the research. The four nozzle depths are 0.5mm, 1mm, 1.5mm and 2mm. whereas 1mm nozzle depth is standard nozzle depth. All four nozzle depths are examined under 120o , 140o , and 160o spray angle. The need of petroleum fuels is increasing everyday despite of their speculation regarding the depletion of petroleum fuels. The petroleum fuels are categorized as suspicious element for human being due to its well known major harmful effects on the environment. The concern is that the need of petroleum fuel is increasing simultaneously with its price in the market. The researchers around the world are focusing either on the reduction of harmful effects which produced from the petroleum fuel or finding another a batter substitute of the petroleum fuel.

Optimization on Reducing Slag Entrapment in 150 × 1270 mm Slab Continuous Casting Mold.

To reduce slag entrapment in 150 × 1270 mm slab continuous casting molds at the Tang Steel Company, the effect of submerged entrance nozzle (SEN) depth and casting speed on the phenomenon was studied by computational fluid dynamics simulations. Then, the slag entrapment behavior in continuous casting molds, utilizing Large Eddy Simulation (LES) by coupling the volume of fluid (VOF) method, was also used. Finally, the effect of several common oils usually used to simulate slag in water modelling on slag entrapment was discussed and the water modelling results were used to validate the numerical simulation findings. The results showed that the optimum scheme is a submerged depth of SEN 90 mm and a casting speed of 1.6 m/min. Under optimal conditions, the maximum surface velocity is smallest (0.335 m/s) and the maximum slag entrapment ratio (0.44%) appears in the position of 0.1 m below the meniscus after 15 s. The water modelling results were in good agreement with the numerical simulation results.

Characterization of the performance of venturi-based aeration devices for use in wastewater treatment in low-resource settings

Low-cost aerators relying on the venturi principle to entrain air into flowing water have the notable advantage of contributing both to water mixing and oxygen transfer, making them attractive for wastewater treatment in low-resource settings. This study aimed to characterize the performance of such aerators by describing the impact of different design characteristics, including water flow rate, the number of nozzles used, and the nozzle depth. The study also explored the effect on aeration performance of temperature, total dissolved solids (TDS) concentration, and addition of the archetypal surfactant sodium dodecyl sulphate (SDS). Tests were conducted in a 200 L reactor with 2, 3 or 4 nozzles, at depths of 20, 40 or 60 cm, while circulating water through the aeration device at a rate of 400, 600 or 800 L/h. The configuration that yielded the highest mass transfer coefficient (KLa20 of 20.8 h-1) had both the highest flow rate (800 L/h) and the smallest number of nozzles (2). Nozzle depth had no detectable effect on performance. The configuration with the highest standard aeration efficiency (SAE) had a low flow rate (400 L/h) and 4 nozzles. The effect of TDS concentration was not detected in the concentration range typical of domestic wastewater (300–1 250 mg/L). The effect of temperature on KLa followed a first-order exponential curve, as reported in the literature (θ = 1.02). Addition of SDS was found to increase the KLa20 of the tested aerator design by up to 60% of its value in tap water, in contrast to results from literature. The performance data obtained herein was compared to other types of aerators. Though venturi nozzles were found to be less efficient than other available technologies, it is proposed that using plunging rather than immersed venturi nozzles could increase performance to an attractive level for low-resource applications.

Vortex characteristics due to nozzle clogging in water caster mould: modelling and validation

ABSTRACTIn continuous slab casting, clogging in the submerged entry nozzle (SEN) ports leads to flow asymmetry and vortex formation in the mould. Knowledge of vortexing and its influence on product quality is fundamental for defect-free production. In this study, the interconnected effects of nozzle clogging and SEN submergence depth, variation on flow asymmetry and vortex characteristics in a 0.4 scale water caster have been characterised by CFD investigation and validated with experimental results from the authors’ previous work. Mean flow velocities at the sub-meniscus and near the port exit predicted by the computational model are compared with the time-averaged values of the impeller probe velocity measurements and found to be in reasonable agreement. Three different clogging conditions (0, 33 and 66% in the left port of the SEN) for SEN submergence depth of 60 mm are studied and the 66% clogging produced vortices having largest diameter, which is consistent with the experimental observations. The effects of SEN submergence depth on flow asymmetry and vortexing are investigated with three different conditions – 40, 60 and 80 mm. It is found that the shallow SEN submergence depth (40 mm) produces vortices of largest diameter and the flow is most stable for a SEN submergence depth of 60 mm among the three cases. Vortex bending towards the SEN as noticed in the experimental observations is also observed in the computational study. This work illustrates the possibility of capturing features of vortexing using validated CFD model.

Sensitivity study of forced convection bubbling in a transparent viscous fluid as a proxy for molten borosilicate glass

Computational fluid dynamic and heat transfer models are being developed for the waste glass melters that will be used to vitrify legacy tank waste at the Hanford site. The objective of this study is to validate the ability of these models to predict the forced convection bubbling in the molten glass at prototypic conditions and scale. Bubbling is used to homogenize the melt pool and increase the melt rate of the batch. Simulations were compared with experimental data obtained with a surrogate liquid under isothermal conditions in an acrylic tank. The simulation results quantify the projected bubble area at the free surface as a function of flow rate and nozzle depth and show agreement with experimental data. Additionally, the local sensitivities of the surface tension and viscosity are evaluated for their effects, since in the melter this parameter directly affects the heat transfer from the molten glass to the reactive batch (or cold cap) layer. From the sensitivity study performed, the viscosity exhibits twice as much influence on bubble projected surface area as the surface tension. In comparison to the grid resolution used in this study, these glass properties produce higher levels of uncertainty.

Modeling viscous effects on boundary layer of rarefied gas flows inside micronozzles in the slip regime condition

The present work provided a numerical investigation of the supersonic flow of rarefied gas into a planar micronozzle characterized by small depth and long divergent section. 2D and 3D computational fluid dynamics (CFD) computations were performed using the continuum Navier-Stokes equations in combination with partial slip conditions at walls, based on a the establishment of the slip regime related to a Knudsen number ranging between 1 x 10-3 and 1 x 10-1. Different partial slip conditions were considered, i.e. the ideal case of pure slip conditions and the full viscous case with Maxwellian slip conditions on sidewalls and planar walls, as well as the case of Maxwellian slip just on sidewalls. The Maxwell slip model was set with a tangential accommodation coefficient equal (TMAC) to 0.8. Comparisons were based on the estimation of the global performance of the micronozzle in terms of thrust force, specific impulse, discharge coefficient and Isp-efficiency.It resulted that when the nozzle depth was neglected, 3D simulations led to the same solution obtained by means of 2D computations inside the micronozzle. The boundary layer thicknesses experienced a linear growth on the sidewalls, and the viscous losses produced a reduction of the performance of about the 95%. Significant differences were found in the prediction of the jet plume, which took the typical bell-shape form in cases involving 2D computations, yet 3D simulations estimated a plume characterized by the succession of oblique shock waves and expansion fan waves. Instead, when the nozzle depth was considered, 3D simulations underlined a completely different behavior of the flow because of the establishment of the nozzle blockage and a viscous heating. The performance suffered an intense degradation of about the 47%, and the analysis of the jet plume highlighted the formation of the Mach disk followed by the typical diamond-shaped subsonic recirculation region.

Effect of Nozzle Depth on Collected Flow Rate of Compound Swirl Jet

Effect of Nozzle Depth on Collected Flow Rate of Compound Swirl Jet

Parameters That Improve Cleaning Efficiency of Subgingival Air Polishing on Titanium Implant Surfaces: An In Vitro Study.

This study aims to reveal how air polishing behaves on a titanium surface by evaluating the size and shape of the cleaned area and the influence of different device settings, probing depths, and cleaning movements. Forty-eight titanium sandblasted large-grit acid-etched surface film-coated disks were treated with an air abrasive system using a subgingival plastic nozzle. Two subgingival models were used: open-ended (step 1) and defined-size (step 2). In step 1, the most effective parameters were investigated by 5-second static applications under different settings. In step 2, the best settings were used for dynamic application to test influence of different movements (up-down, slowly up, rotation). For both steps, powder and water consumption and total cleaned area were calculated. Air pressure was the main factor with the strongest effect on cleaning. Increasing air pressure extended cleaning area. Other factors, such as nozzle depth and excessive powder flow amount, had weak influence. Cleaning effect reached deeper than the nozzle physically reached. Step 2 showed that there was no significant difference between different nozzle movements; however, cleaning efficiency decreased significantly without movement. For the most effective clinical use of air polishing, it should be applied with high pressure, deep insertion of nozzle, and enough water flow. Additionally, the nozzle has to be moved to get the best cleaning effect.

Large Eddy Simulations of the Effects of EMBr and SEN Submergence Depth on Turbulent Flow in the Mold Region of a Steel Caster

Transient turbulent flow in the mold region during continuous casting of steel is related to many quality problems, such as surface defects and slag entrainment. This work applies an efficient multi-GPU based code, CUFlow, to perform large eddy simulations (LES) of the turbulent flow in a domain that includes the slide gate, SEN, and mold region. The computations were first validated by comparing the predicted surface velocity with plant measurements. Then, seven LES simulations were conducted to study the effects of casting speed, electromagnetic braking (EMBr) field strength, and submerged entry nozzle (SEN) depth on the transient flow. The results show that EMBr has an important influence on flow inside the SEN, in addition to flow in the mold. With EMBr, an “M-shaped” flow profile is seen inside the SEN. The swirling flow behavior in the SEN and ports is more symmetrical at high casting speed and with higher EMBr strength. The position of the SEN ports relative to the peak magnetic field affects the EMBr performance. The results confirm and quantify how applying EMBr greatly lowers both the magnitude and turbulent variations of the surface velocity and level profile.

Numerical Investigation of the Free Surface in a Model Mold

The transient-free surface behavior in a model mold is evaluated numerically by performing the unsteady Reynolds-averaged Navier-Stokes (RANS) simulation and the two-phase approach volume of fluid (VOF). Simulation is conducted in this study by means of the open source computational fluid dynamics library OpenFOAM®. The calculations indicate the effect of nozzle depth and jet velocity at the nozzle port on the free surface profile. Recent experimental results are used to validate the free surface contour gained from the numerical simulations. A good overall agreement is found between experiment and simulation. The typical single-roll and double-roll are observed in the mold depending on the nozzle depth and the inlet velocity.