Effect of Turbulence Inhibitors on Molten Steel Flow in 66-Ton T-Type Tundish with Large Impact Area

Cheng Yao; Min Wang; Ruixuan Zheng; Mingxu Pan; Jinyuan Rao; Yanping Bao

doi:10.3390/met10091111

Effect of Turbulence Inhibitors on Molten Steel Flow in 66-Ton T-Type Tundish with Large Impact Area

Metals ◽

10.3390/met10091111 ◽

2020 ◽

Vol 10 (9) ◽

pp. 1111

Author(s):

Cheng Yao ◽

Min Wang ◽

Ruixuan Zheng ◽

Mingxu Pan ◽

Jinyuan Rao ◽

...

Keyword(s):

Prediction Model ◽

Flow Pattern ◽

Volume Fraction ◽

Steel Slag ◽

Surface Velocity ◽

Vof Model ◽

Impact Area ◽

Turbulence Inhibitor ◽

The Impact ◽

Interface Fluctuation

A multiphase numerical simulation of the steel-slag flow was established by using the volume of fluid (VOF) model to study the effect of different turbulence inhibitors on the improvement of the steel-slag flow in the tundish. The steel-slag interface fluctuation was studied by vorticity magnitude and transient fluctuation change. A prediction model of residence time distribution (RTD) curve was established based on mathematical simulation and the error of prediction model can be controlled below 6% by comparing with the hydraulic results. The results show that jet flow into the tundish generated very different flow patterns. Case 1 produced a double-roll flow pattern and case 2 produced a four-roll flow pattern in the impact area. The ratio of vorticity magnitude above 1.00 s−1 near the ladle shroud was 2.60% in case 1 and the ratio of vorticity magnitude above 1.00 s−1 near the ladle shroud was 13.15% in case 2, which indicates case 2 increased the possibility of slag entrainment via the upward flow mechanism and shear layer instability. Surface velocity fluctuations in case 2 were much more severe near the ladle shroud. The thickness of the slag layer was 60 mm, the interface fluctuation towards surface in case 2 was close to 20 mm. Meanwhile, case 1 involved very small volume-fraction contours near interface. The turbulence inhibitor with internal ripples (case 1) showed a better optimization effect and the results could provide a theoretical basis for the selection of a suitable turbulence inhibitor for the 66-ton T-type tundish.

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Investigation on the control of multiphase flow behavior in a continuous casting tundish during ladle change

Metallurgical Research & Technology ◽

10.1051/metal/2020070 ◽

2020 ◽

Vol 117 (6) ◽

pp. 619

Author(s):

Rui Xu ◽

Haitao Ling ◽

Haijun Wang ◽

Lizhong Chang ◽

Shengtao Qiu

Keyword(s):

Multiphase Flow ◽

Flow Behavior ◽

Rolled Strip ◽

Impact Zone ◽

Steel Cleanliness ◽

Carry Over ◽

Slag Carry Over ◽

Hot Rolled ◽

Turbulence Inhibitor ◽

The Impact

The transient multiphase flow behavior in a single-strand tundish during ladle change was studied using physical modeling. The water and silicon oil were employed to simulate the liquid steel and slag. The effect of the turbulence inhibitor on the slag entrainment and the steel exposure during ladle change were evaluated and discussed. The effect of the slag carry-over on the water-oil-air flow was also analyzed. For the original tundish, the top oil phase in the impact zone was continuously dragged into the tundish bath and opened during ladle change, forming an emulsification phenomenon. By decreasing the liquid velocities in the upper part of the impact zone, the turbulence inhibitor decreased considerably the amount of entrained slag and the steel exposure during ladle change, thereby eliminating the emulsification phenomenon. Furthermore, the use of the TI-2 effectively lowered the effect of the slag carry-over on the steel cleanliness by controlling the movement of slag droplets. The results from industrial trials indicated that the application of the TI-2 reduced considerably the number of linear inclusions caused by ladle change in hot-rolled strip coils.

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Nanofluid flow containing carbon nanotubes with quartic autocatalytic chemical reaction and Thompson and Troian slip at the boundary

Scientific Reports ◽

10.1038/s41598-020-74855-7 ◽

2020 ◽

Vol 10 (1) ◽

Cited By ~ 1

Author(s):

Muhammad Ramzan ◽

Jae Dong Chung ◽

Seifedine Kadry ◽

Yu-Ming Chu ◽

Muhammad Akhtar

Keyword(s):

Mathematical Model ◽

Carbon Nanotubes ◽

Drag Force ◽

Chemical Reaction ◽

Slip Velocity ◽

Volume Fraction ◽

Surface Drag ◽

Nanofluid Flow ◽

Velocity Parameter ◽

The Impact

Abstract A mathematical model is envisioned to discourse the impact of Thompson and Troian slip boundary in the carbon nanotubes suspended nanofluid flow near a stagnation point along an expanding/contracting surface. The water is considered as a base fluid and both types of carbon nanotubes i.e., single-wall (SWCNTs) and multi-wall (MWCNTs) are considered. The flow is taken in a Dacry-Forchheimer porous media amalgamated with quartic autocatalysis chemical reaction. Additional impacts added to the novelty of the mathematical model are the heat generation/absorption and buoyancy effect. The dimensionless variables led the envisaged mathematical model to a physical problem. The numerical solution is then found by engaging MATLAB built-in bvp4c function for non-dimensional velocity, temperature, and homogeneous-heterogeneous reactions. The validation of the proposed mathematical model is ascertained by comparing it with a published article in limiting case. An excellent consensus is accomplished in this regard. The behavior of numerous dimensionless flow variables including solid volume fraction, inertia coefficient, velocity ratio parameter, porosity parameter, slip velocity parameter, magnetic parameter, Schmidt number, and strength of homogeneous/heterogeneous reaction parameters are portrayed via graphical illustrations. Computational iterations for surface drag force are tabulated to analyze the impacts at the stretched surface. It is witnessed that the slip velocity parameter enhances the fluid stream velocity and diminishes the surface drag force. Furthermore, the concentration of the nanofluid flow is augmented for higher estimates of quartic autocatalysis chemical.

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Low-carbon cast microalloyed steel intercritically heat-treated at different temperatures: microstructure and mechanical properties

Archives of Civil and Mechanical Engineering ◽

10.1007/s43452-021-00222-6 ◽

2021 ◽

Vol 21 (2) ◽

Author(s):

Hadi Torkamani ◽

Shahram Raygan ◽

Carlos Garcia Mateo ◽

Yahya Palizdar ◽

Jafar Rassizadehghani ◽

...

Keyword(s):

Carbon Content ◽

Volume Fraction ◽

Block Size ◽

Tensile Tests ◽

Total Elongation ◽

Martensite Phase ◽

Low Carbon ◽

Steel Increase ◽

Different Temperatures ◽

The Impact

AbstractIn this study, dual-phase (DP, ferrite + martensite) microstructures were obtained by performing intercritical heat treatments (IHT) at 750 and 800 °C followed by quenching. Decreasing the IHT temperature from 800 to 750 °C leads to: (i) a decrease in the volume fraction of austenite (martensite after quenching) from 0.68 to 0.36; (ii) ~ 100 °C decrease in martensite start temperature (Ms), mainly due to the higher carbon content of austenite and its smaller grains at 750 °C; (iii) a reduction in the block size of martensite from 1.9 to 1.2 μm as measured by EBSD. Having a higher carbon content and a finer block size, the localized microhardness of martensite islands increases from 380 HV (800 °C) to 504 HV (750 °C). Moreover, despite the different volume fractions of martensite obtained in DP microstructures, the hardness of the steels remained unchanged by changing the IHT temperature (~ 234 to 238 HV). Applying lower IHT temperature (lower fraction of martensite), the impact energy even decreased from 12 to 9 J due to the brittleness of the martensite phase. The results of the tensile tests indicate that by increasing the IHT temperature, the yield and ultimate tensile strengths of the DP steel increase from 493 to 770 MPa, and from 908 to 1080 MPa, respectively, while the total elongation decreases from 9.8 to 4.5%. In contrast to the normalized sample, formation of martensite in the DP steels could eliminate the yield point phenomenon in the tensile curves, as it generates free dislocations in adjacent ferrite.

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Aircraft Impact Effects on an Aged NPP

Materials ◽

10.3390/ma14040816 ◽

2021 ◽

Vol 14 (4) ◽

pp. 816

Author(s):

Rosa Lo Frano

Keyword(s):

Nuclear Power ◽

Military Aircraft ◽

Residual Resistance ◽

Plant Safety ◽

Need To Evaluate ◽

Target Wall ◽

Impact Area ◽

Wall Perforation ◽

The Impact ◽

Loss Of Strength

The impact of an aircraft is widely known to be one of the worst events that can occur during the operation of a plant (classified for this reason as beyond design). This can become much more catastrophic and lead to the loss of strength of/collapse of the structures when it occurs in the presence of ageing (degradation and alteration) materials. Therefore, since the performance of all plant components may be affected by ageing, there is a need to evaluate the effect that aged components have on system performance and plant safety. This study addresses the numerical simulation of an aged Nuclear Power Plant (NPP) subjected to a military aircraft impact. The effects of impact velocity, direction, and location were investigated together with the more unfavorable conditions to be expected for the plant. The modelling method was also validated based on the results obtained from the experiments of Sugano et al., 1993. Non-linear analyses by means of finite element (FE) MARC code allowed us to simulate the performance of the reinforced concrete containment building and its impact on plant availability and reliability. The results showed that ageing increases a plant’s propensity to suffer damage. The damage at the impact area was confirmed to be dependent on the type of aircraft involved and the target wall thickness. The greater the degradation of the materials, the lower the residual resistance capacity, and the greater the risk of wall perforation.

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Influence of the Spatial Pressure Distribution of Breaking Wave Loading on the Dynamic Response of Wolf Rock Lighthouse

Journal of Marine Science and Engineering ◽

10.3390/jmse9010055 ◽

2021 ◽

Vol 9 (1) ◽

pp. 55

Author(s):

Darshana T. Dassanayake ◽

Alessandro Antonini ◽

Athanasios Pappas ◽

Alison Raby ◽

James Mark William Brownjohn ◽

...

Keyword(s):

Dynamic Response ◽

Pressure Distribution ◽

Distinct Element ◽

Breaking Waves ◽

Breaking Wave ◽

Wave Loading ◽

Wave Impact ◽

Pressure Distributions ◽

Impact Area ◽

The Impact

The survivability analysis of offshore rock lighthouses requires several assumptions of the pressure distribution due to the breaking wave loading (Raby et al. (2019), Antonini et al. (2019). Due to the peculiar bathymetries and topographies of rock pinnacles, there is no dedicated formula to properly quantify the loads induced by the breaking waves on offshore rock lighthouses. Wienke’s formula (Wienke and Oumeraci (2005) was used in this study to estimate the loads, even though it was not derived for breaking waves on offshore rock lighthouses, but rather for the breaking wave loading on offshore monopiles. However, a thorough sensitivity analysis of the effects of the assumed pressure distribution has never been performed. In this paper, by means of the Wolf Rock lighthouse distinct element model, we quantified the influence of the pressure distributions on the dynamic response of the lighthouse structure. Different pressure distributions were tested, while keeping the initial wave impact area and pressure integrated force unchanged, in order to quantify the effect of different pressure distribution patterns. The pressure distributions considered in this paper showed subtle differences in the overall dynamic structure responses; however, pressure distribution #3, based on published experimental data such as Tanimoto et al. (1986) and Zhou et al. (1991) gave the largest displacements. This scenario has a triangular pressure distribution with a peak at the centroid of the impact area, which then linearly decreases to zero at the top and bottom boundaries of the impact area. The azimuthal horizontal distribution was adopted from Wienke and Oumeraci’s work (2005). The main findings of this study will be of interest not only for the assessment of rock lighthouses but also for all the cylindrical structures built on rock pinnacles or rocky coastlines (with steep foreshore slopes) and exposed to harsh breaking wave loading.

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Lasting effects of prenatal exposure to Cannabis in the retina of the offspring: an experimental study in mice

International Journal of Retina and Vitreous ◽

10.1186/s40942-021-00314-8 ◽

2021 ◽

Vol 7 (1) ◽

Author(s):

Paulo Roberto Arruda Zantut ◽

Mariana Matera Veras ◽

Sarah Gomes Menezes Benevenutto ◽

Angélica Mendonça Vaz Safatle ◽

Ricardo Augusto Pecora ◽

...

Keyword(s):

Young Adult ◽

Light Microscopy ◽

Prenatal Exposure ◽

Structural Changes ◽

Volume Fraction ◽

Clinical Care ◽

Retinal Layer ◽

Exposed Population ◽

The Central Nervous System ◽

The Impact

Abstract Background Prenatal exposure to Cannabis is a worldwide growing problem. Although retina is part of the central nervous system, the impact of maternal Cannabis use on the retinal development and its postnatal consequences remains unknown. As the prenatal period is potentially sensitive in the normal development of the retina, we hypothesized that recreational use of Cannabis during pregnancy may alter retina structure in the offspring. To test this, we developed a murine model that mimics human exposure in terms of dose and use. Methods Pregnant BalbC mice were exposed daily for 5 min to Cannabis smoke (0.2 g of Cannabis) or filtered air, from gestational day 5 to 18 (N = 10/group). After weaning period, pups were separated and examined weekly. On days 60, 120, 200, and 360 after birth, 10 pups from each group were randomly selected for Spectral Domain Optical Coherence Tomography (SD-OCT) analysis of the retina. All retina layers were measured and inner, outer, and total retina thickness were calculated. Other 37 mice from both groups were sacrificed on days 20, 60, and 360 for retinal stereology (total volume of the retina and volume fraction of each retinal layer) and light microscopy. Means and standard deviations were calculated and MANOVA was performed. Results The retina of animals which mother was exposed to Cannabis during gestation was 17% thinner on day 120 (young adult) than controls (P = 0.003) due to 21% thinning of the outer retina (P = 0.001). The offspring of mice from the exposed group presented thickening of the IS/OS in comparison to controls on day 200 (P < 0.001). In the volumetric analyzes by retinal stereology, the exposed mice presented transitory increase of the IS/OS total volume and volume fraction on day 60 (young adult) compared to controls (P = 0.008 and P = 0.035, respectively). On light microscopy, exposed mice presented thickening of the IS/OS on day 360 (adult) compared to controls (P = 0.03). Conclusion Gestational exposure to Cannabis smoke may cause structural changes in the retina of the offspring that return to normal on mice adulthood. These experimental evidences suggest that children and young adults whose mothers smoked Cannabis during pregnancy may require earlier and more frequent clinical care than the non-exposed population.

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Insulation Characteristics of Sisal Fibre/Epoxy Composites

International Journal of Polymer Science ◽

10.1155/2017/7312609 ◽

2017 ◽

Vol 2017 ◽

pp. 1-6 ◽

Cited By ~ 2

Author(s):

A. Shalwan ◽

M. Alajmi ◽

A. Alajmi

Keyword(s):

Volume Fraction ◽

Fibre Volume Fraction ◽

Thermal Characteristics ◽

Fibre Volume ◽

Point Of View ◽

Natural Fibres ◽

Epoxy Composites ◽

Ongoing Research ◽

Sisal Fibre ◽

The Impact

Using natural fibres in civil engineering is the aim of many industrial and academics sectors to overcome the impact of synthetic fibres on environments. One of the potential applications of natural fibres composites is to be implemented in insulation components. Thermal behaviour of polymer composites based on natural fibres is recent ongoing research. In this article, thermal characteristics of sisal fibre reinforced epoxy composites are evaluated for treated and untreated fibres considering different volume fractions of 0–30%. The results revealed that the increase in the fibre volume fraction increased the insulation performance of the composites for both treated and untreated fibres. More than 200% insulation rate was achieved at the volume fraction of 20% of treated sisal fibres. Untreated fibres showed about 400% insulation rate; however, it is not recommended to use untreated fibres from mechanical point of view. The results indicated that there is potential of using the developed composites for insulation purposes.

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Experimental Model of Temperature-Driven Nanofluid

Journal of Heat Transfer ◽

10.1115/1.2717239 ◽

2006 ◽

Vol 129 (6) ◽

pp. 697-704 ◽

Cited By ~ 152

Author(s):

A. G. Agwu Nnanna

Keyword(s):

Heat Transfer ◽

Convective Heat Transfer ◽

Convective Heat ◽

Small Volume ◽

Volume Fraction ◽

Convective Heat Transfer Coefficient ◽

Isothermal Condition ◽

Carrier Fluid ◽

Small Volume Fraction ◽

The Impact

This paper presents a systematic experimental method of studying the heat transfer behavior of buoyancy-driven nanofluids. The presence of nanoparticles in buoyancy-driven flows affects the thermophysical properties of the fluid and consequently alters the rate of heat transfer. The focus of this paper is to estimate the range of volume fractions that results in maximum thermal enhancement and the impact of volume fraction on Nusselt number. The test cell for the nanofluid is a two-dimensional rectangular enclosure with differentially heated vertical walls and adiabatic horizontal walls filled with 27 nm Al2O3–H2O nanofluid. Simulations were performed to measure the transient and steady-state thermal response of nanofluid to imposed isothermal condition. The volume fraction is varied between 0% and 8%. It is observed that the trend of the temporal and spatial evolution of temperature profile for the nanofluid mimics that of the carrier fluid. Hence, the behaviors of both fluids are similar. Results shows that for small volume fraction, 0.2⩽ϕ⩽2% the presence of the nanoparticles does not impede the free convective heat transfer, rather it augments the rate of heat transfer. However, for large volume fraction ϕ>2%, the convective heat transfer coefficient declines due to reduction in the Rayleigh number caused by increase in kinematic viscosity. Also, an empirical correlation for Nuϕ as a function of ϕ and Ra has been developed, and it is observed that the nanoparticle enhances heat transfer rate even at a small volume fraction.

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Grinding Force Model for Low-Speed Grinding Based on Impact Principle

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.797.123 ◽

2013 ◽

Vol 797 ◽

pp. 123-128

Author(s):

Ming He Liu ◽

Xiu Ming Zhang ◽

Shi Chao Xiu

Keyword(s):

Sliding Friction ◽

Impact Load ◽

Grinding Force ◽

Calculation Model ◽

Force Model ◽

Grinding Process ◽

Low Speed ◽

Impact Area ◽

Force Mechanism ◽

The Impact

In the low-speed grinding process, the force generated when the wheel grinding the workpiece is the result of sliding friction, plough and cutting. While in the actual study, the cutting process has attracted extensive attention. Impact effect to the entire grinding process on the contact is ignored so that the error exists between the calculation grinding force and the measured grinding force. Basing on the shock effect to the grinding process, the paper divides the contact area into impact area and cutting area. And the model of impact load generated from single grit is built. Moreover, the grinding force theoretical calculation model and total grinding force mathematical model is also constructed by analyzing the impact load affecting on the grinding force mechanism. Finally experimental study verifies the correctness of theoretical analysis.

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