Ekman boundary layer mass transfer mechanism of free sink vortex

Tan, Dapeng; Li, Lin; Yin, Zichao; Li, Daifeng; Zhu, Yin-long; Zheng, Shuai

doi:10.1016/j.ijheatmasstransfer.2019.119250

Cited by 55 publications

(16 citation statements)

References 52 publications

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“…The computational fluid dynamic software Fluent was used to solve the mathematical model with separate solution. The Pressure Implicit with Splitting of Operators (PISO) algorithm was chosen for coupling the pressure and velocity terms to guarantee convergence efficiency . The discrete pressure interpolation was adopted to avoid tremendous change of internal pressure and high swirl by the Pressure Staggering Option (PRESTO).…”

Section: Model Descriptionsmentioning

confidence: 99%

Physical and Mathematical Simulation of Surface‐Free Vortex Formation and Vortex Prevention Design during the End of Casting in Tundish

Ruan

Yao

Shen

et al. 2020

steel research int.

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Herein, the formation of the vortex and slag entrainment in tundish is studied by using mathematical and physical simulation. This article aims at contributing to the understanding of the free surface vortex formation in continuous casting tundish at the end of casting. A 3D multiphase mathematical model using the renormalization group (RNG) k–ε turbulence model is developed to predict the vortex formation and slag layer behavior on the scale of the 1:4 water model of a two‐strand slab tundish. The Eulerian volume of fluid model is adopted to track the steel–slag–air free surface and vortex, and the effect of Coriolis force is considered in this simulation. An improved vortex prevention design is also proposed by changing the position of the diversion hole on the dam of the tundish, which is compared with the original scheme using numerical and physical simulation. The predicted results of the vortex structure and the critical height of the vortex formation agree well with the water modeling results. It is demonstrated that the critical height of the vortex formation is reduced significantly by regulating the position of the diversion hole on the dam near the outlet of the tundish.

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Section: Model Descriptionsmentioning

confidence: 99%

Physical and Mathematical Simulation of Surface‐Free Vortex Formation and Vortex Prevention Design during the End of Casting in Tundish

Ruan

Yao

Shen

et al. 2020

steel research int.

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“…The other way to combat noise is the design of image reconstruction, which perform Wiener filtering [15] or rational orthogonal wavelet analysis filter bank [16] to suppress noise in active radar on the basis of MIMO waveform design. The shallow water environment is a complicated media with the sea surface upward and the seafloor downward [17,18]. For active sonar in shallow water environments, since the received signal is distorted due to the time-delay and Doppler spread caused by the channel, the received signal comprises the ambiguity of both the transmitted signal and the channel.…”

Section: Introductionmentioning

confidence: 99%

An Iterative Deconvolution-Time Reversal Method with Noise Reduction, a High Resolution and Sidelobe Suppression for Active Sonar in Shallow Water Environments

Guo

Zhao

2020

Sensors

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Matched filtering is widely used in active sonar because of its simplicity and ease of implementation. However, the resolution performance generally depends on the transmitted waveform. Moreover, its detection performance is limited by the high-level sidelobes and seriously degraded in a shallow water environment due to time spread induced by multipath propagation. This paper proposed a method named iterative deconvolution-time reversal (ID-TR), on which the energy of the cross-ambiguity function is modeled, as a convolution of the energy of the auto-ambiguity function of the transmitted signal with the generalized target reflectivity density. Similarly, the generalized target reflectivity density is a convolution of the spread function of channel with the reflectivity density of target as well. The ambiguity caused by the transmitted signal and the spread function of channel are removed by Richardson-Lucy iterative deconvolution and the time reversal processing, respectively. Moreover, this is a special case of the Richardson-Lucy algorithm that the blur function is one-dimensional and time-invariant. Therefore, the iteration deconvolution is actually implemented by the iterative temporal time reversal processing. Due to the iterative time reversal method can focus more and more energy on the strongest target with the iterative number increasing and then the peak-signal power increases, the simulated result shows that the noise reduction can achieve 250 dB in the “ideal” free field environment and 100 dB in a strong multipaths waveguide environment if a 1-ms linear frequency modulation with a 4-kHz frequency bandwidth is transmitted and the number of iteration is 10. Moreover, the range resolution is approximately a delta function. The results of the experiment in a tank show that the noise level is suppressed by more than 70 dB and the reverberation level is suppressed by 3 dB in the case of a single target and the iteration number being 8.

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“…Although CaO is capable to partially catalyze tar reduction, previous studies have shown that such effect is quite limited, and it is difficult to reduce tar concentration to a level at which biomass syngas can be directly used. Insufficient removal of biomass tar will result in lower gasification efficiency as well as plugging and fouling problems . Moreover, deposition of tar coke on absorbent surface may also cover CaO active site for CO 2 capture, which further decrease CaO carbonation reactivity …”

Section: Introductionmentioning

confidence: 99%

Catalytic Toluene Reforming with In Situ CO₂ Capture via an Iron–Calcium Hybrid Absorbent for Promoted Hydrogen Production

Han

Liu

Yuan³

et al. 2020

Energy Tech

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A two‐step sol–gel method is adopted to prepare an iron–calcium hybrid absorbent (Ca–Al–Fe) integrating iron catalysis component and inert support with CaO for calcium looping gasification. Effects of Ca–Al–Fe on cyclic CO2 capture reactivity, mechanical strength, and enhanced reforming of biomass tar model component (toluene) are investigated by comparing with three reference absorbents. Results show that main components of Ca–Al–Fe are CaO, mayenite (Ca12Al14O33), and brownmillerite (Ca2Fe2O5). Ca12Al14O33 plays key roles in keeping stable cyclic carbonation reactivity and significantly promotes mechanical strength of the novel absorbent. In comparison with other absorbents without coupling Ca12Al14O33 or Ca2Fe2O5, Ca–Al–Fe approaches the highest toluene conversion (around 60%) and has the lowest coke deposition (12.2 mg g−1), due to the synergetic influences of Ca2Fe2O5 and Ca12Al14O33, which significantly promotes hydrogen production while reducing CO2 yield in reforming syngas. In addition, influences of reaction conditions such as iron loading, reaction temperature, molar ratio of H2O to carbon in toluene, and absorbent particle size on toluene reforming are examined in the presence of Ca–Al–Fe. Potential reaction routes of toluene reforming are also analyzed and discussed.

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Ekman boundary layer mass transfer mechanism of free sink vortex

Cited by 55 publications

References 52 publications

Physical and Mathematical Simulation of Surface‐Free Vortex Formation and Vortex Prevention Design during the End of Casting in Tundish

Physical and Mathematical Simulation of Surface‐Free Vortex Formation and Vortex Prevention Design during the End of Casting in Tundish

An Iterative Deconvolution-Time Reversal Method with Noise Reduction, a High Resolution and Sidelobe Suppression for Active Sonar in Shallow Water Environments

Catalytic Toluene Reforming with In Situ CO₂ Capture via an Iron–Calcium Hybrid Absorbent for Promoted Hydrogen Production

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Ekman boundary layer mass transfer mechanism of free sink vortex

Cited by 55 publications

References 52 publications

Physical and Mathematical Simulation of Surface‐Free Vortex Formation and Vortex Prevention Design during the End of Casting in Tundish

Physical and Mathematical Simulation of Surface‐Free Vortex Formation and Vortex Prevention Design during the End of Casting in Tundish

An Iterative Deconvolution-Time Reversal Method with Noise Reduction, a High Resolution and Sidelobe Suppression for Active Sonar in Shallow Water Environments

Catalytic Toluene Reforming with In Situ CO2 Capture via an Iron–Calcium Hybrid Absorbent for Promoted Hydrogen Production

Contact Info

Product

Resources

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Catalytic Toluene Reforming with In Situ CO₂ Capture via an Iron–Calcium Hybrid Absorbent for Promoted Hydrogen Production