Port Angle Research Articles

Effect of Nozzle Port Angle on Transient Flow and Surface Slag Behavior During Continuous Steel-Slab Casting

Undesirable flow variations can cause severe instabilities at the interface between liquid mold flux and molten steel across the mold top-region during continuous steel casting, resulting in surface defects in the final products. A three-dimensional Large Eddy Simulation (LES) model using the volume of fluid method for the slag and molten steel phases is validated with plant measurements, and applied to gain new insights into the effects of nozzle port angle on transient flow, top slag/steel interface movement, and slag behavior during continuous slab casting under nominally steady conditions. Upward-angled ports produce a single-roll flow pattern with lower surface velocity, due to rapid momentum dissipation of the spreading jet. However, strong jet wobbling from the port leads to greater interface variations. Severe level drops allow easy entrapment of liquid flux by the solidifying steel shell at the meniscus. Sudden level rises may also be detrimental, leading to overflow of the solidified meniscus region. Downward-angled ports produce a classic double-roll pattern with less jet turbulence and a more stable interface everywhere except near the narrow faces. Finally, the flow patterns, surface velocity, and level predicted from the validated LES model are compared with steady-state standard k-e model predictions.

Behavior of molten steel flow in continuous casting mold with different static magnetic field configurations

A three-dimensional mathematical model was established to investigate the behavior of molten steel flow and steel/slag interface with different processes and electromagnetic parameters under two different static magnetic field configurations [ruler-type electromagnetic brake (EMBr ruler) and vertical electromagnetic brake (V-EMBr)] in a continuous casting mold. The results showed that the brake effect of EMBr ruler is significantly influenced by its configuration parameters, the distance between the pole and bottom of the submerged entry nozzle (SEN), and the port angle of the SEN outlet; therefore, it is not helpful to depress the diffusion of jet flow along the thickness direction of mold. For a constant SEN depth and port angle, there is a reasonable pole position (P = 0 mm) where the pole simultaneously covers three key zones, i.e., the jet flow impact zone and the upward and downward backflow zones. For V-EMBr, the magnetic field can simultaneously cover the three key zones and depress the diffusion of jet flow along the casting and thickness directions of the mold. Both the meniscus height and the impact intensity of the jet flow can be obviously depressed by V-EMBr even if the SEN depth and port angle have changed in the continuous casting process.

Effect of Port Angle of Sen on Melt Flow in a Mold

The molten metal from tundish is directed to continuous casting mold by submerged entry nozzle SEN The SEN is usually bifurcated nozzle which is made of different shape and angle The melt flow structure in mold plays an important role Thus port of SEN is made at different angles to control the melt structure Many authors have reported that longitudinal high magnitude of melt and subsequent production of turbulence causes severe defects in casted products In the present work the melt flow structure has been studied under different port angles It has been seen that melt flow has been modified in the continuous casting mold Moreover it was found that the change in SEN port angle affects vertical downward velocity and turbulence behavior in the molten steel region nbsp

Influence of Vertical Electromagnetic Brake on the Steel/Slag Interface Behavior in a Slab Mold

The steel/slag interface behavior under a new type of electromagnetic brake (EMBr), vertical electromagnetic brake (V-EMBr), was investigated. The influence of the magnetic induction intensity, the submerged entry nozzle (SEN) immersion depth, and the port angle of the SEN are investigated numerically. The effect of magnetic induction intensity on the meniscus fluctuation of molten alloy is further studied by the experiments. The results show that the meniscus fluctuation is depressed as the magnetic induction intensity is increased, especially for the region in the vicinity of the narrow face of the slab mold. This result is validated by the following experiments. For the influence of the SEN immersion depth and the port angle, the results show that the meniscus fluctuation is suppressed as the values of the immersion depth and the port angle are increased (absolute values for the port angle). However, the influence of the immersion depth and the port angle are not as sensitive as those in the other type of EMBr, e.g., EMBr Ruler. The industrial application of V-EMBr could benefit from this result.

Influence of SEN depth and port angle on vertical electromagnetic brake effects in continuous casting mould

PurposeTo effectively control the molten steel flow and the stability of free surface in continuous casting mould, this paper aims to propose a new type electromagnetic brake technique, namely, vertical electromagnetic brake (V-EMBr). Its brake effect under special processing parameters such as submerged entry nozzle (SEN) depth and port angle is evaluated by the numerical simulation methods.Design/methodology/approachA couple three-dimensional mathematical model of fluid flow and static magnetic field was developed to investigate the behaviour of molten steel flow and steel/slag interface in the continuous casting mould, and a volume of fluid model is used to track the interfacial behaviour of molten steel and liquid slag by solving the continuity equation of the phase volume fraction.FindingsThe simulation results showed that the application of V-EMBr can significantly reduce the flow intensity in upper recirculation zone and decrease the meniscus height and the flow velocity of molten steel in the vicinity of narrow side of mould, which is beneficial to reduce the possibility of mould flux entrapment. Especially, the brake effect of V-EMBr has a little affected by the SEN depth and port angle, which is helpful for V-EMBr to better adapt the actual continuous casting process.Originality/valueCompared to the conventional-level EMBr, the new proposed V-EMBr has the advantage to effectively control the molten steel flow and steel/slag interfacial fluctuation in the vicinity of narrow side of mould with a pair of magnetic fields, and its brake effect is less affected by the changes in continuous casting processing parameters.

The influence of the geometry of a three orifice nozzle on the flow field inside a beam blank mold

A single nozzle design with three lateral ports has been proposed to feed a beam blank mold. Techniques of physical modeling and computational fluid dynamics (CFD) were applied to evaluate the fluid flow as a function of port angle, immersion depth and flow rate. The overall features of the flow field are not affected by changing the values of these parameters. The proposed design is characterized by: increasing fluctuation intensity at the meniscus and high impact velocities in certain regions of the broad face of the flanges. The oscillation intensity increases with decreasing immersion depth, increasing inclination of the exit ports, and increasing flow rates. These values vary also along the free surface of the mold, being larger on the flange opposite to the submerged entry nozzle (SEN) for all configurations. The impact velocities at the flange were affected only by the flow rate, reaching a maximum value of 0.45m/s.

Flow pattern control in continuous slab casting moulds: physical modelling and plant trials

Full-scale water modelling studies combined with nail-dipping industrial trials at Shougang Jingtang (SGJT) Works were carried out in order to investigate the parameters that influence flow patterns in the continuous slab casting mould. The effects of casting speed/mould width combinations, argon bubbling flow rates, submerged entry nozzle (SEN) immersion depths and SEN geometries (port angle and bottom shape) on the flow patterns were examined. A CMI factor defined as casting speed/mould width ratio index is put forward to describe the combined effect of these parameters on the fluid flow patterns in the mould. The results show that the CMI and argon injection rates are the dominant factors that determine the flow pattern. On the basis of the results from this study, critical argon flow rates for different casting combinations have been evaluated. These findings provide operating guidelines for generating optimal flow patterns based on double roll flow with appropriate surface velocities in continuous slab casting moulds. On the basis of these considerations, slab quality at SGJT Works was substantially improved and the percentage of flow pattern-related sliver defects in cold rolled products was decreased from 4.5 to 2.3%.

히트 펌프용 비대칭 스크롤 압축기의 가스 인젝션 포트 설계

For an asymmetric scroll compressor for heat pump application, a numerical simulation was carried out to investigate the effects of injection port design on the compressor`s performance under gas injection. To validate the simulation, the numerical results were compared with experimental results obtained from a scroll compressor with a base injection port design. There was good agreement between simulation and experimental results, with around a 1% difference in the injection mass flow rate when the injection pressure was below for the heating mode. Various injection port angular positions were numerically tested to yield better injection performance. The largest improvement in heating capacity was obtained at angles of and inward from the scroll wrap end angle for low-temperature and standard heating conditions, respectively, while the maximum COP improvement was at and , respectively. A considerable improvement in cooling capacity was also found at the injection port angle of .

Designing of Sub-entry Nozzle for Casting Defect-free Steel

Production of defect-free steel is a continuous demand for each & every steel maker. The design of refractories used in steel making process has a vital role on this. Manufacturing of cleaner steel is mostly attributed to the continuous casting process of the steel plant. Defects in steel mainly come from the non-metallic inclusions present in steel that are incorporated during various steel making process. During continuous casting, the main focus is to remove these inclusions to cast defect free steel. The flow pattern of molten steel in the mould plays a vital role in the removal of these impurities. The turbulence of the flowing steel in the mould should be such that more and more impurities will be floated at the meniscus of the mould and they will be captured by the casting powder. But, this turbulence should not be higher enough to capture the particles of casting powder inside the molten steel. So, in order to optimize the turbulent intensity and to get uniform distribution of temperature and velocity in the mould, the design of Sub-entry nozzle (SEN) is very crucial. SEN is used to guide the flow of steel from tundish to mould during continuous casting. The bore configuration and outlet design of SEN along with its immersed depth in the mould determine the flow pattern of steel inside the mould, which is the key factor to produce cleaner steel. This paper focuses on the different designing aspects of SEN to get an optimized and uniform flow of steel in the mould. The designing parameters include bore diameter, bore configuration, port shape, port angle, port dimension, number of ports and immersed depth of SEN inside the mould. Design optimization is done to improve the steel quality by removing the impurities.

400cc급 소형엔진 흡기포트의 성능 개발

본 연구에서는 유동해석과 실험을 통하여 소형엔진 흡기포트의 성능 최적화를 수행하였다. 포트각, 플랜지면적 및 포트형상은 흡기포트의 성능을 결정하는 중요한 설계인자이다. 특히 가공곡률이 공기유량계수에 매우 중요한 영향을 미치는 핵심인자임을 확인하였다. 포트각과 플랜지면적이 증가하면, 흡기포트내의 압력분포와 압력기울기가 개선되어 공기유량계수가 개선되었다. 유동해석 결과는 플로우박스 실험결과 대비 최대 8% 오차를 보였으나, 설계변수에 따른 공기유량계수 경향을 우수하게 반영하였다. 최적의 설계변수를 적용한 흡기포트 모델은 양산모델 대비 약 4.5% 개선된 공기유량계수 성능을 나타내었다. Performance optimization of a small engine intake port has been studied through computational and experimental approach. Port angle, flange area and port shape are very important design parameters affecting performance of an intake port. Especially, radius of curvature of intake port inner surface has major effect on the flow coefficient of an intake port. As increasing port angle and flange area, flow coefficient is increased because pressure distribution and pressure gradient in the intake port are improved. Even though computational results over-predict maximum 8% compared with experimental result, they describe the tendency of flow coefficient according to the design parameters. Optimized intake port shows about 4.5% improved flow performance.

An investigation on effect of geometrical parameters on spray cone angle and droplet size distribution of a two-fluid atomizer

A visual study is conducted to determine the effect of geometrical parameters of a two-fluid atomizer on its spray cone angle. The liquid (water) jets exit from six peripheral inclined orifices and are introduced to a high speed gas (air) stream in the gravitational direction. Using a high speed imaging system, the spray cone angle has been determined in constant operational conditions, i.e., Reynolds and Weber numbers for different nozzle geometries. Also, the droplet sizes (Sauter mean diameter) and their distributions have been determined using Malvern Master Sizer x. The investigated geometrical parameters are the liquid jet diameter, liquid port angle and the length of the gas-liquid mixing chamber. The results show that among these parameters, the liquid jet diameter has a significant effect on spray cone angle. In addition, an empirical correlation has been obtained to predict the spray cone angle of the present two-fluid atomizer in terms of nozzle geometries.

Flow visualization for different port angles of a pulsatile ventricular assist device

The "washout effect" inside a blood pump may depend in part on the configuration of the blood pump, including its "port angle." The port angle, which is primarily decided based on anatomical considerations, may also be important from the rheological viewpoint. In our department, a next-generation diaphragm-type blood pump is being developed. In this study, we examined the influence of the port angle on flow conditions inside our new blood pump. Acrylic resin mock pumps with three different port angles (0°, 30°, and 45°) were prepared for flow visualization. Mechanical monoleaflet valves were mounted on the inlet and outlet ports of the mock pumps. Flow conditions within the mock pumps were visualized by means of particle image velocimetry during a half stroke. As a result, a high flow velocity region was seen along the main circular flow from the inlet to the outlet port. This circular flow was almost uniform and parallel to the plane of the diaphragm-housing junction (DhJ) when viewed from the inlet and outlet sides. Moreover, the proportion of high flow velocity vectors in the plane in the vicinity of the DhJ decreased as the degree of the port angle increased. In conclusion, we found that the flow behavior in the plane in the vicinity of the DhJ changed with the port angle, and that a port angle of 0° may be suitable for our diaphragm-type blood pump in view of the washout effect.

Water Model Experiments on Surface Flow Velocity of Molten Steel in Slab Caster Mold

Based on the slab caster mold of ChengGang Company as prototype, the water model with 1:1 scale was used to study the effects of casting speed、nozzle port angle、immersion depth、bottom structure、mold width and other parameters on the surface flow velocity of liquid steel in slab caster mold. The results show that the effect of casting speed is biggest and with increase in the casting speed, the surface flow velocity of liquid steel is prominently increased, when the mold width at 1650mm, the surface flow velocity from 0.04m/s to 0.1m/s with the casting speed from 0.7m/min increased to 1.4m/min

Simulation of Shell Thickness Distribution and Flow Field in Slab Continuous Casting Mold

The shell distribution in the slab continuous casting mold has been simulated coupling a 3-D flow, temperature and volume fraction equations of the molten steel in FLUENT. The simulated results show that the flow velocity around the upper vortex center is decrease and the location of lower vortex center move down as the nozzle port angle increases. The simulated shell thickness in the center on the narrow face become thicker at meniscus and the shell thickness in the center on wide face decreases but the basic distributions of the shell tend to consistency as the nozzle port angle increases. The simulated results also show that the effects of solidified shell on flow field in mold is slight but the velocity of molten steel near the solidified shell. There are remelting near the impact regoins implicit our attentions in order to avoid breaking out.

Interfacial Fluctuation Behavior of Steel/Slag in Medium-Thin Slab Continuous Casting Mold With Argon Gas Injection

The flow field of molten steel and the interfacial behaviour between molten steel and liquid slag layer in medium-thin slab continuous casting mold with argon gas injection were studied by numerical simulation, in which the effects of nozzle submergence depth and port angle, casting speed, and argon gas flow rate on the flow and the level fluctuation of molten steel were considered. The results show that the molten steel is jetted from the submerged entry nozzle (SEN) with three ports into the mold and forms three recirculation zones including one upper recirculation zone and two lower recirculation zones. Argon gas injection results in a secondary vortex flow in the upper zone near the nozzle. For a given casting speed and argon gas flow rate, increasing the side port angle and submergence depth of nozzle can effectively restrain the steel/slag interfacial fluctuation. Increasing the casting speed would prick up the level fluctuation. For a fixed casting speed, argon gas flow rate has a critical value, the interfacial fluctuation with argon gas injection are stronger than the case without argon gas injection when the argon gas flow rate is less than the critical value, but when the argon gas flow rate exceeds the critical value, the level fluctuation is calmer than that without argon gas injection.

Effect of Sen Design on Surface Fluctuation and Solidifying Shell in Slab Mold and Its Optimization

Turbulent flow and heat transfer coupled with solidification in slab continuous casting mold was studied by numerical simulation method. Volume of fluid (VOF) model is used to solve steel-air two-phase flow problem and enthalpy-porosity scheme is introduced to solve the fluid flow problem involving solidification. Contributions of various nozzle port angles and port widths and heights on the free surface fluctuation and the thickness of solidifying shell in slab mold were particularly investigated, based on which the structure of submerged entry nozzle was optimized. Flow inside the common nozzle port cannot fill the entire outlet area, having a recirculation in the upper portion of the port, which is enlarged for the nozzle port with both larger height and width. Results show that the flow in mold cavity is mainly controlled by the nozzle port angle. The increase of the angle of upper face of the port to shape a roughly streamlined inner-wall improves the effective area fraction of the nozzle, resulting in less jet impingement, weaker free surface turbulence and thicker solidifying steel shell.

New Centrifugal Blood Pump With Dual Impeller and Double Pivot Bearing System: Wear Evaluation in Bearing System, Performance Tests, and Preliminary Hemolysis Tests

A new dual impeller centrifugal blood pump has been developed as a research collaboration between Baylor College of Medicine and Institute Dante Pazzanese of Cardiology for long-term left ventricle assist device (LVAD). A design feature of this new pump is a dual impeller that aims to minimize a stagnant flow pattern around the inlet port. Several different materials were tested in order to adopt a double pivot bearing design originally developed by Prof. Dr. Yukihiko Nosé from Baylor College of Medicine. Hydraulic performance tests were conducted with two different inlet ports' angle configurations 30 degrees and 45 degrees . Pump with inlet port angle of 45 degrees achieved best values of pressure ahead and flow after 1800 rpm. Preliminary hemolysis tests were conducted using human blood. The pump showed good performance results and no alarming trace of hemolysis, proving to be a feasible long-term LVAD.

Investigation of Fluid Flow and Steel Cleanliness in the Continuous Casting Strand

Fluid flow in the mold region of the continuous slab caster at Panzhihua Steel is investigated with 0.6-scale water model experiments, industrial measurements, and numerical simulations. In the water model, multiphase fluid flow in the submerged entry nozzle (SEN) and the mold with gas injection is investigated. Top surface level fluctuations, pressure at the jet impingement point, and the flow pattern in the mold are measured with changing submergence depth, SEN geometry, mold width, water flow rate, and argon gas flow rate. In the industrial investigation, the top surface shape and slag thickness are measured, and steel cleanliness including inclusions and the total oxygen (TO) content are quantified and analyzed, comparing the old and new nozzle designs. Three kinds of fluid flow pattern are observed in the SEN: ‘‘bubbly flow,’’ ‘‘annular flow,’’ and an intermediate critical flow structure. The annular flow structure induces detrimental asymmetrical flow and worse level fluctuations in the mold. The SEN flow structure depends on the liquid flow rate, the gas flow rate, and the liquid height in the tundish. The gas flow rate should be decreased at low casting speed in order to maintain stable bubbly flow, which produces desirable symmetrical flow. Two main flow patterns are observed in the mold: single roll and double roll. The single-roll flow pattern is generated by large gas injection, small SEN submergence depth, and low casting speed. To maintain a stable double-roll flow pattern, which is often optimal, the argon should be kept safely below a critical level. The chosen optimal nozzle had 45-mm inner bore diameter, downward 15 deg port angle, 2.27 port-to-bore area ratio, and a recessed bottom. The pointed-bottom SEN generates smaller level fluctuations at the meniscus, larger impingement pressure, deeper impingement, and more inclusion entrapment in the strand than the recess-bottom SEN. Mass balances of inclusions in the steel slag from slag and slab measurements show that around 20 pct of the alumina inclusions are removed from the steel into the mold slag. However, entrainment of the mold slag itself is a critical problem. Inclusions in the steel slabs increase twofold during ladle changes and tenfold during the start and end of a sequence. All of the findings in the current study are important for controlling slag entrainment.

Experimental Simulation and Mathematical Modeling of Air Bubble Movement in Slab Caster Mold

Experimental simulation of air bubble movement in a 1/3rd scale model slab caster mold has been done for parallel, upward and downward port submerged entry nozzle (SEN) with different water flow and air flow rates in order to study the bubble penetration depth, horizontal dispersion and the air jet angle. It has been observed that the bubble penetration depth depends more on the flow rate of water rather than that of air. The bubble penetration depth also depends on the port angle and on the “well” provided on the SEN. Below a certain critical water flow rate the flow becomes asymmetric in the slab caster mold for a given flow rate of air. SEN with a well depth may help to avoid bubble entrapment defects in the slab at the cost of higher surface disturbances on the mold. A mathematical modeling of the air bubble movement in water was also carried out for the same experimental set up where it was observed that for same air flow rate the bubble penetration depth was more for higher water flow rate confirming to the experimental findings. The experience gained from the experiment and mathematical modeling helped to fine tune the parameters at the caster so that the strike rate of ultra low carbon grade steel could be improved substantially.

Large Eddy Simulation of Turbulent Flow with the Effects of DC Magnetic Field and Vortex Brake Application in Continuous Casting

Vortexing flow exists in the free surface of molten steel in the slab continuous casting process and leads to uncleanness of steel. A large eddy simulation (LES) model has been developed to simulate the vortexing flow phenomena with the effect of DC magnetic field and vortex brake application in the slab continuous casting process. The influence of the submerged entry nozzle (SEN) port angle and the SEN depth to the turbulent vortex was analyzed and the mechanism of the turbulent vortex and the biased vortex formation was found. The vortexing flow is the result of shearing of the two unsymmetric surface flows from the mold narrow faces when they meet adjacent to the SEN. The unsymmetric surface flow comes from the unsymmetric upward re-circulating flow, which is caused by turbulent energy of the fluid for turbulent vortex and caused by biased flow and the turbulent energy of fluid for biased vortex. The new vortex brake can eliminate the turbulent vortex and suppress the biased vortex significantly by removing the downward component of the vortexing flow. When the magnetic field is located at the free surface, the turbulent vortex and the biased vortex can be eliminated.