Study on Propellers Distribution and Flow Field in the Oxidation Ditch Based on Two-Phase CFD Model

Zhang, Yuquan; Li, Chengyi; Xu, Yanhe; Tang, Qinghong; Zheng, Yuan; Liu, Huiwen; Fernández-Rodríguez, Emmanuel

doi:10.3390/w11122506

Cited by 11 publications

(9 citation statements)

References 29 publications

(48 reference statements)

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“…Similarly for the die steels (Figure 7b), a significant change in the XRD pattern at 500 • C was that new phase of Fe 2 O 3 could be identified as compared to those at RT and 200 • C, which indicated the presence of a fraction of the oxide wear debris. Furthermore, the intensities of oxide peaks for the die steel were obviously higher than those for the coating after sliding wear at 500 • C. This may have been because of the presence of the fcc-Co phase (as evidenced in TEM analysis of the coating), whose oxidize rate is relatively low at high temperatures [36,47]. Therefore, the HVOF-sprayed WC-CoCr coating exhibits potential application on Cr12MoV cold work die steel.…”

Section: Worn Surfaces Analysismentioning

confidence: 99%

Improvement in Tribological Properties of Cr12MoV Cold Work Die Steel by HVOF Sprayed WC-CoCr Cermet Coatings

Hong

Wang

et al. 2019

Coatings

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The main objective of this study was to develop an efficient coating to increase the wear resistance of cold work die steel at different temperatures. The microstructures of high-velocity oxygen-fuel (HVOF)-sprayed WC-CoCr coatings were evaluated using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The effect of temperature on the tribological properties of the coatings and the reference Cr12MoV cold work die steel were both investigated by SEM, environmental scanning electron microscopy (ESEM), X-ray diffraction (XRD), and a pin-on-disk high-temperature tribometer. The coating exhibited a significantly lower wear rate and superior resistance against sliding wear as compared to the die steel at each test temperature, whereas no major differences in terms of the variation tendency of the friction coefficient as a function of temperature were observed in both the coatings and the die steels. These can be attributed to the presence of nanocrystalline grains and the fcc-Co phase in the coating. Moreover, the wear mechanisms of the coatings and the die steels were compared and discussed. The coating presented herein provided a competitive approach to improve the sliding wear performance of cold work die steel.

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Section: Worn Surfaces Analysismentioning

confidence: 99%

Improvement in Tribological Properties of Cr12MoV Cold Work Die Steel by HVOF Sprayed WC-CoCr Cermet Coatings

Hong

Wang

et al. 2019

Coatings

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“…The standard two equation k-ε (k-epsilon) turbulence closure model (Pope, 2000) solves two additional transport equations for turbulence quantities: velocity scale turbulent kinetic energy, k, and turbulence length scale eddy dissipation rate, ε. This turbulence model is the most popular for an oxidation ditch due to its robustness, low computational cost and reasonable accuracy (Cockx et al, 2001;Fayolle et al, 2007;Lei and Ni, 2014;Xu et al, 2010;Zhang et al, 2019). The two-equation turbulence models assume isotropic turbulence (Launder and Spalding, 1974).…”

Section: Two Equation K-ε Turbulence Modelmentioning

confidence: 99%

Computational fluid dynamics simulation of two-phase flow and dissolved oxygen in a wastewater treatment oxidation ditch

Matko

Chew

Wenk

et al. 2021

Process Safety and Environmental Protection

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This paper presents a computational fluid dynamics (CFD) model of an aerated wastewater treatment oxidation ditch, taking into account gas-liquid flow, mass transfer and dissolved oxygen. This innovative study contributes to knowledge as it considers the effect of bubble size distribution (BSD) and biochemical oxygen demand (BOD) distribution on the dissolved oxygen (DO) distribution. Species transport modelling predicts the DO and BOD distribution. De-oxygenation of local dissolved oxygen by BOD is modelled by an oxygen sink that depends on the local BOD concentration. Bubble coalescence and breakup models predict the BSD. The behaviour of the ditch is non-ideal, which is indicated by the residence time distribution (RTD) and the heterogeneous flow pattern and DO distribution. The parameters with the greatest influence on the dissolved oxygen are the BOD and bubble size. There is good agreement with the observed flow patterns and the measurements of mean DO. This study identifies that the BOD distribution and the BSD are important parameters for predicting the dissolved oxygen distribution and are also current gaps in the published research.

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“…The qualities ρu i u j are viewed as Reynolds stress; the presence of Reynolds stress implies the N-S equations are not closed, so some approximations are used to close the equations. The Reynolds stress can be expressed as [17,54]…”

Section: Equation Discretization and Boundary Conditionsmentioning

confidence: 99%

Performance Investigation of the Immersed Depth Effects on a Water Wheel Using Experimental and Numerical Analyses

Zhao

Zheng

Yang

et al. 2020

Water

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The purpose of this research is to study the effect of different immersed depths on water wheel performance and flow characteristics using numerical simulations. The results indicate that the simulation methods are consistent with experiments with a maximum error less than 5%. Under the same rotational speeds, the efficiency is much higher and the fluctuation amplitude of the torque is much smaller as the immersed radius ratio increases, and until an immersed radius ratio of 82.76%, the wheel shows the best performance, achieving a maximum efficiency of 18.05% at a tip-speed ratio (TSR) of 0.1984. The average difference in water level increases as the immersed radius ratio increases until 82.76%. The water area is much wider and the water volume fraction shows more intense change at the inlet stage at a deep immersed depth. At an immersed radius ratio of 82.76%, some air intrudes into the water at the inlet stage, coupled with a dramatic change in the water volume fraction that would make the flow more complex. Furthermore, eddies are found to gradually generate in a single flow channel nearly at the same time, except for an immersed depth of 1.2 m. However, eddies generate in two flow channels and can develop initial vortexes earlier than other cases because of the elevation of the upstream water level at an immersed radius ratio of 82.76%.

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Study on Propellers Distribution and Flow Field in the Oxidation Ditch Based on Two-Phase CFD Model

Cited by 11 publications

References 29 publications

Improvement in Tribological Properties of Cr12MoV Cold Work Die Steel by HVOF Sprayed WC-CoCr Cermet Coatings

Improvement in Tribological Properties of Cr12MoV Cold Work Die Steel by HVOF Sprayed WC-CoCr Cermet Coatings

Computational fluid dynamics simulation of two-phase flow and dissolved oxygen in a wastewater treatment oxidation ditch

Performance Investigation of the Immersed Depth Effects on a Water Wheel Using Experimental and Numerical Analyses

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