Numerical analysis for the coating thickness prediction in continuous hot-dip galvanizing

Kwon, Soon Bum; Kwon, Yuri; Lee, Sung‐Jin; Shin, Seung-Young; Kim, Geunyoung

doi:10.1007/s12206-009-1008-x

Cited by 8 publications

(6 citation statements)

References 6 publications

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“…Such a growth has been shown in previous studies. 3,[8][9][10]19,20) In order to find out such a growth at far downstream, the computational domain in the longitudinal direction is extended up to 90 mm, and the same grid spacing and time step have been used. Table 1 shows the computational results for computed film thickness averaged over the transverse direction at various y-locations and the standard deviation of the fluctuating film thickness over the transverse direction.…”

Section: Computational Results and Discussionmentioning

confidence: 99%

CFD Analysis of Sag Line Formation on the Zinc-coated Steel Strip after the Gas-jet Wiping in the Continuous Hot-dip Galvanizing Process

Yoon

Chung

2011

ISIJ Int.

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of the coating thickness for long wavelength perturbations. Ellen and Tu 3) have suggested a non-dimensional model that takes into account the surface shear stress and their model gives significantly more accurate prediction of the final coating thickness. Also, Tu and Wood 4) have experimentally demonstrated that the final coating thickness depends on both the pressure and shear stress distributions on the strip surface. Although Tuck and Vanden-Broeck.5) and Yoneda 6) suggested that the final thickness depends on the surface tension and the shear stress on the strip, recently Gosset and Buchlin 7) have shown that the surface tension does not play any role in determining the final coating thickness.There have appeared several numerical simulations of the gas wiping process to predict the final coating thickness by using CFD. One of the recent studies is that by Lacanette et al. 8,9) who numerically simulated the final coating thickness by using volume of fluid-large eddy simulation (VOF-LES) modeling. Their results were satisfactorily compared with their experimental data. They found that the coating thickness is independent of the nozzle-to-plate distance when it is smaller than 8 times of the nozzle slot width. Myrillas et al. 10) tried to validate a model for the gas jet-liquid film interaction in the gas wiping process. In their study, they found that two-phase numerical simulations using LES is more suited to model of the complex interaction than k-e turbulence model. Through these previous studies it can be concluded that the dominant factors affecting the final coating thickness are pressure gradient and shear stress on the strip.So far, most of the previous studies were focused on the average final coating thickness along longitudinal direction and their numerical and mathematical models are made in two-dimensional domain. In spite of its good productivity and easy control of the zinc coating thickness, however, the coated film surface after gas wiping has frequently three dimensional surface defects such as dents, blow lines, peculiar features and sag-lines.11) Therefore, in order to obtain a uniform coating on the strip, it is necessary to investigate in details the three dimensional character of the coated surface after the gas wiping process.Among these surface defects, the sag lines (or snaky coating) cause many problems such as irregularity in the electrical and thermal characteristics and the diffused reflection on the coated surface. The snaky coating is that with an oblique patterns appearing on the coated film surface after the gas wiping process. Depending on its seriousness, the snaky coating is usually classified into five grades as shown in Fig. 2. The arrows in Fig. 2 indicate the moving direction of steel strip. The first grade indicates that no sag line is observed on the surface. In the surface pattern of the 2nd grade, rather short sag lines appear irregularly, thus a pattern of sag lines is vaguely discernible. On the other hand, the 3rd-5th grade snaky coatings reveal oblique...

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Section: Computational Results and Discussionmentioning

confidence: 99%

CFD Analysis of Sag Line Formation on the Zinc-coated Steel Strip after the Gas-jet Wiping in the Continuous Hot-dip Galvanizing Process

Yoon

Chung

2011

ISIJ Int.

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“…In the GMM rod (9) occurs a corresponding deformation and displace- As shown in Figure 3, according to the selection and test of the magnetostrictive actuator, the mechanical structure of the braking part of the magnetostrictive disc brake was further designed. The brake contains the giant-magnetostrictive actuator (3), which consists of the outer shell (7), the winding frame and coil (8), GMM rod (9) and end cover (10) (which also includes a retightening spring applying a retightening force and a magnetic yoke sealing magnetic circuit). When the giant-magnetostrictive actuator receives the braking signal, the winding frame coil (8) passes a current and generates the corresponding magnetic field.…”

Section: Magnetostrictive Disc Brake Structure Designmentioning

confidence: 99%

“…Chihoon Jo et al proposed a clamping force control algorithm considering friction characteristics and clamping force estimation for the clamping force control problem of a planetary reducer type EMB, which has a good control effect [9]. Soon-Bum Kwon and Y. H. Ki et al proposed their own algorithms for an EMB system to estimate the clamping force [10,11]. Chihoon Jo et al not only estimated the clamping force for an EMB system but also designed the clamping force control algorithm [9].…”

Section: Introductionmentioning

confidence: 99%

Controller Design of a Brake-By-Wire System Based on Giant-Magnetostrictive Material for an Intelligent Vehicle

2022

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Mechatronics control technology can not only improve the performance of vehicles but also solve traditional automotive braking system problems such as long brake pipeline, lots of valve components, slow response and so on. In this paper, a giant-magnetostrictive actuator and a disc brake structure were used to build a drive control system, and the control system module was designed with a single-chip microcomputer as the core. Combined with sensor selection, software programming control was used to build the experimental test platform, and the maximum output displacement of the control system was 0.112156 mm, which was basically consistent with the theoretical calculation. The maximum output force was 3883 N, which exceeded the minimum output force of 3631 N calculated theoretically. According to the results of the test platform, the relevant test parameters were highly consistent with the theoretical calculation, which verified the correctness and effectiveness of the theoretical calculation and bench testbed design. It contributes to the improvement of vehicle active safety performance and can provide a new way for the development of an intelligent vehicle brake-by-wire system.

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“…But, there is no appropriate alternative to calculate the distributions of the wall jet pressure and the shear stress at present. Also the film thickness is so thin (around below 10 µm) [14], that it was assumed that the impinging wall jet pressure and the wall shear stress without the liquid film is equal to the value with liquid film. It is a validation of the previous assumption which is verified by the comparison of distributions in impinging wall jet pressure and the wall shear stress with the distributions for the case of the liquid film.…”

Section: Numerical Analysismentioning

confidence: 99%

A suggestion of a new method for the calculation of the coating thickness in continuous hot-dip galvanizing

Kim

Kwon

et al. 2011

J Mech Sci Technol

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It is known that the distributions of the impinging pressure gradient and the shear stress at the strip surface play a decisive key role in the decision of the coating thickness in hot-dip galvanizing. So, to predict the exact coating thickness, it is essential that the distributions of the impinging wall jet pressure and the shear stress acting between the liquid film and jet stream are measured (or calculated) exactly for each specific coating condition. So far, to obtain the impinging wall jet pressure, it was assumed that the jet issuing from an air-knife is similar to the Hiemenz plane stagnation flow, and the wall shear stress could be predicted by an equation using the assumption of a non-negative Gaussian profile in impinging wall jet pressure in general, so that it cannot be reliable for some impinging wall jet regions and nozzle systems intrinsically. Nevertheless, one cannot find a suitable method to cope with the difficulties in measuring/calculating of the shear stress and the impinging wall jet pressure. Such a difficulty which will cause an inaccuracy in the coating thickness prediction. With these connections, in the present study, we suggest a new method named as a two-step calculation method to calculate the final coating thickness, which consists of the air jet analysis and coating thickness calculation. And, from the comparison of the results one may confirm the validation of the new suggested method.

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Numerical analysis for the coating thickness prediction in continuous hot-dip galvanizing

Cited by 8 publications

References 6 publications

CFD Analysis of Sag Line Formation on the Zinc-coated Steel Strip after the Gas-jet Wiping in the Continuous Hot-dip Galvanizing Process

CFD Analysis of Sag Line Formation on the Zinc-coated Steel Strip after the Gas-jet Wiping in the Continuous Hot-dip Galvanizing Process

Controller Design of a Brake-By-Wire System Based on Giant-Magnetostrictive Material for an Intelligent Vehicle

A suggestion of a new method for the calculation of the coating thickness in continuous hot-dip galvanizing

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