Electrocatalytic oxidation is a promising technology for wastewater treatment,but poor mass transfer and low current efficiency impaded its engineering applications.To address these issues,researchers have developed f...Electrocatalytic oxidation is a promising technology for wastewater treatment,but poor mass transfer and low current efficiency impaded its engineering applications.To address these issues,researchers have developed flow-through electrochemical reactors(FERs)primarily based on porous electrodes,where the pore structure significantly impacts the electrochemical reaction.Therefore,this study systematically investigated the impact of different pore sizes on the fluid dynamics,current potential distribution,mass transfer processes,and degradation performance of FERs.Computational Fluid Dynamics(CFD)results indicated that smaller pore sizes(10μm,30μm,and 60μm)significantly enhanced convective effects within the fluid,reduced short fluid paths and dead volume regions within the microchannels,and facilitated mass transfer processes.Additionally,smaller pore sizes were conducive to a uniform distribution of current density.Furthermore,Fe(CN)_(6)^(4−)oxidation experiments revealed that the current density at a pore size of 160μm was notably lower than that at 10μm,indicating slower mass transfer of Fe(CN)_(6)^(4−)within larger channels.Calculations based on experimental results demonstrated that the mass transfer rate at a pore size of 10μm was six times than that at 160μm,further confirming the enhancing effect of smaller pore sizes on the mass transfer process.Lastly,experiments on tetracycline degradation showed that at a residence time of 90 s,the removal efficiencies of tetracycline were 80%and 39.1%for porous electrodes with pore sizes of 10μm and 160μm,respectively,demonstrating the superior removal efficiency of smaller pore sizes for tetracycline degradation.展开更多
This study introduces a novel flow-through cowcatcher with integrated inlet and outlet channels as an aerodynamic noise mitigation strategy for the nose car of a high-speed train.The wall-adapting local eddy-viscosity...This study introduces a novel flow-through cowcatcher with integrated inlet and outlet channels as an aerodynamic noise mitigation strategy for the nose car of a high-speed train.The wall-adapting local eddy-viscosity large eddy simulation(WALE-LES)combined with the Ffowcs Williams-Hawkings(FW-H)acoustic analogy approach is employed to evaluate its impact on the aerodynamic and aeroacoustic characteristics of the leading bogie region.Compared with the conventional closed cowcatcher,results show that the flow-through structure suppresses the flow separation,promotes more stable vortex evolution within the bogie cavity,and reduces the spatial extent of high amplitude wall pressure fluctuations up to 40%,mitigating effectively the generation of aerodynamic noise.Semi anechoic wind tunnel experiments validate the simulation results and demonstrate that the sound pressure levels at the far field observers decrease by 0.4-0.6 dB(A)with the flow-through cowcatcher applied underneath the nose car.The dominant sound source around the leading bogie region is shrunk with intensity reduced about 1.0 dB(A).These findings confirm the effectiveness of the flow-through cowcatcher in reducing the aerodynamic noise produced from the leading bogie region,providing both theoretical insight and engineering guidance for structural optimization and low-noise design of the nose car in a high-speed train.展开更多
基金supported by the National Natural Science Foundation of China(Nos.U22A20241 and 21876105)Shaanxi“Scientist&Engineer”Team(No.2023KXJ-131)Xianyang Key S&T Special Projects(No.L2023-ZDKJ-QCY-SXGG-GY-007).
文摘Electrocatalytic oxidation is a promising technology for wastewater treatment,but poor mass transfer and low current efficiency impaded its engineering applications.To address these issues,researchers have developed flow-through electrochemical reactors(FERs)primarily based on porous electrodes,where the pore structure significantly impacts the electrochemical reaction.Therefore,this study systematically investigated the impact of different pore sizes on the fluid dynamics,current potential distribution,mass transfer processes,and degradation performance of FERs.Computational Fluid Dynamics(CFD)results indicated that smaller pore sizes(10μm,30μm,and 60μm)significantly enhanced convective effects within the fluid,reduced short fluid paths and dead volume regions within the microchannels,and facilitated mass transfer processes.Additionally,smaller pore sizes were conducive to a uniform distribution of current density.Furthermore,Fe(CN)_(6)^(4−)oxidation experiments revealed that the current density at a pore size of 160μm was notably lower than that at 10μm,indicating slower mass transfer of Fe(CN)_(6)^(4−)within larger channels.Calculations based on experimental results demonstrated that the mass transfer rate at a pore size of 10μm was six times than that at 160μm,further confirming the enhancing effect of smaller pore sizes on the mass transfer process.Lastly,experiments on tetracycline degradation showed that at a residence time of 90 s,the removal efficiencies of tetracycline were 80%and 39.1%for porous electrodes with pore sizes of 10μm and 160μm,respectively,demonstrating the superior removal efficiency of smaller pore sizes for tetracycline degradation.
基金Projects(51875411,52232013)supported by the National Natural Science Foundation of ChinaProject(19DZ2290400)supported by the Shanghai Professional Technical Service Platform Program,China。
文摘This study introduces a novel flow-through cowcatcher with integrated inlet and outlet channels as an aerodynamic noise mitigation strategy for the nose car of a high-speed train.The wall-adapting local eddy-viscosity large eddy simulation(WALE-LES)combined with the Ffowcs Williams-Hawkings(FW-H)acoustic analogy approach is employed to evaluate its impact on the aerodynamic and aeroacoustic characteristics of the leading bogie region.Compared with the conventional closed cowcatcher,results show that the flow-through structure suppresses the flow separation,promotes more stable vortex evolution within the bogie cavity,and reduces the spatial extent of high amplitude wall pressure fluctuations up to 40%,mitigating effectively the generation of aerodynamic noise.Semi anechoic wind tunnel experiments validate the simulation results and demonstrate that the sound pressure levels at the far field observers decrease by 0.4-0.6 dB(A)with the flow-through cowcatcher applied underneath the nose car.The dominant sound source around the leading bogie region is shrunk with intensity reduced about 1.0 dB(A).These findings confirm the effectiveness of the flow-through cowcatcher in reducing the aerodynamic noise produced from the leading bogie region,providing both theoretical insight and engineering guidance for structural optimization and low-noise design of the nose car in a high-speed train.
