The flow distribution in quench tank for heat treatment of A357 alloy large complicated components was simulated using FLUENT computational fluid dynamics（CFD） software.The flow velocity and the uniformity of flow f...The flow distribution in quench tank for heat treatment of A357 alloy large complicated components was simulated using FLUENT computational fluid dynamics（CFD） software.The flow velocity and the uniformity of flow field in two types of quench tanks（with or without agitation system） were calculated.The results show that the flow field in the quench tank without agitation system has not evident regularity.While as for the quench tank with agitation system,the flow fields in different parameters have certain regularity.The agitation tanks have a distinct advantage over the system without agitation.Proper process parameters were also obtained.Finally,the tank model established in this work was testified by an example from publication.This model with high accuracy is able to optimize the tank structures and can be helpful for industrial production and theoretical investigation in the fields of heat treatment of large complicated components.展开更多
Based on the computational fluid dynamics （CFD） method, a quenching tank with two agitator systems and two flow-equilibrating devices was selected to simulate flow distribution using Fluent software. A numerical exa...Based on the computational fluid dynamics （CFD） method, a quenching tank with two agitator systems and two flow-equilibrating devices was selected to simulate flow distribution using Fluent software. A numerical example was used to testify the validity of the quenching tank model. In order to take tank parameters （agitation speed, position of directional flow baffle and coordinate position in quench zone） into account, an approach that combines the artificial neural network （ANN） with CFD method was developed to study the flow distribution in the quenching tank. The flow rate of the quenching medium shows a very good agreement between the ANN predicted results and the Fluent simulated data. Methods for the optimal design of the quenching tank can be used as technical support for industrial production.展开更多
This paper reports an investigation of Computational Fluid Dynamics(CFD)on the influence of injection momentum rate of premixed air and fuel on the flameless Moderate or Intense Low oxygen Dilution(MILD) combustion in...This paper reports an investigation of Computational Fluid Dynamics(CFD)on the influence of injection momentum rate of premixed air and fuel on the flameless Moderate or Intense Low oxygen Dilution(MILD) combustion in a recuperative furnace.Details of the furnace flow velocity,temperature,O2,CO2 and NOx concentrations are provided.Results obtained suggest that the flue gas recirculation plays a vital role in establishing the premixed MILD combustion.It is also revealed that there is a critical momentum rate of the fuel-air mixture below which MILD combustion does not occur.Moreover,the momentum rate appears to have less significant influence on conventional global combustion than on MILD combustion.展开更多
The partial oxidation of hydrocarbons is an important technical route to produce acetylene for chemical industry.The partial oxidation reactor is the key to high acetylene yields.This work is an experimental and numer...The partial oxidation of hydrocarbons is an important technical route to produce acetylene for chemical industry.The partial oxidation reactor is the key to high acetylene yields.This work is an experimental and numerical study on the use of a methane flame to produce acetylene.A lab scale partial oxidation reactor was used to produce ultra fuel-rich premixed jet flames.The axial temperature and species concentration profiles were measured for different equivalence ratios and preheating temperatures,and these were compared to numerical results from Computational Fluid Dynamics(CFD)simulations that used the Reynolds Averaged Navier-Stokes Probability Density Function(RANS-PDF)approach coupled with detailed chemical mechanisms.The Leeds 1.5,GRI 3.0 and San Diego mechanisms were used to investigate the effect of the detailed chemical mechanisms.The effects of equivalence ratio and preheating temperature on acetylene production were experimentally and numerically studied.The experimental validations indicated that the present numerical simulation provided reliable prediction on the partial oxidation of methane.Using this simulation method the optimal equivalence ratio for acetylene production was determined to be 3.6.Increasing preheating temperature improved acetylene production and shortened greatly the ignition delay time.So the increase of preheating temperature had to be limited to avoid uncontrolled ignition in the mixing chamber and the pyrolysis of methane in the preheater.展开更多
Effect of different fire strengths on the smoke distribution in the subway station is investigated. Shin-Gum-Ho station （line #5） in Seoui is selected as a case study for variation of CO （carbon monoxide） distribu...Effect of different fire strengths on the smoke distribution in the subway station is investigated. Shin-Gum-Ho station （line #5） in Seoui is selected as a case study for variation of CO （carbon monoxide） distribution caused by the fire in the platform. The ventilation in the station is set to be an air supply mod in the lobby and an air exhaustion mod in the platform. One-side main tunnel ventilation （7,000 m3/min） is applied to operate in the tunnel. The fire is assumed to break out in the middle of train parked in the platform tunnel. Two kinds of fire strength are used. One is 10 MW and the other is 20 MW. Ventilation diffusers in the station are modeled as 317 square shapes ＆ four rectangular shapes in the lobby and platform. The total of 7.5 million grids is generated and whole domain is divided to 22 blocks for parallel computation. Large eddy simulation method is applied to solve the momentum equation. The behavior of CO is calculated according to different fire strengths and compared with each other.展开更多
基金Project(51405389)supported by the National Natural Science Foundation of ChinaProject(2014003)supported by the Shanghai Key Laboratory of Digital Manufacture for Thin-walled Structures,China+1 种基金Project(3102015ZY024)supported by the Fundamental Research Funds for the Central Universities,ChinaProject(108-QP-2014)supported by the Research Fund of the State Key Laboratory of Solidification Processing,Northwestern Polytechnical University,China
文摘The flow distribution in quench tank for heat treatment of A357 alloy large complicated components was simulated using FLUENT computational fluid dynamics（CFD） software.The flow velocity and the uniformity of flow field in two types of quench tanks（with or without agitation system） were calculated.The results show that the flow field in the quench tank without agitation system has not evident regularity.While as for the quench tank with agitation system,the flow fields in different parameters have certain regularity.The agitation tanks have a distinct advantage over the system without agitation.Proper process parameters were also obtained.Finally,the tank model established in this work was testified by an example from publication.This model with high accuracy is able to optimize the tank structures and can be helpful for industrial production and theoretical investigation in the fields of heat treatment of large complicated components.
文摘Based on the computational fluid dynamics （CFD） method, a quenching tank with two agitator systems and two flow-equilibrating devices was selected to simulate flow distribution using Fluent software. A numerical example was used to testify the validity of the quenching tank model. In order to take tank parameters （agitation speed, position of directional flow baffle and coordinate position in quench zone） into account, an approach that combines the artificial neural network （ANN） with CFD method was developed to study the flow distribution in the quenching tank. The flow rate of the quenching medium shows a very good agreement between the ANN predicted results and the Fluent simulated data. Methods for the optimal design of the quenching tank can be used as technical support for industrial production.
基金Supported by the National Natural Science Foundation of China(50936001)
文摘This paper reports an investigation of Computational Fluid Dynamics(CFD)on the influence of injection momentum rate of premixed air and fuel on the flameless Moderate or Intense Low oxygen Dilution(MILD) combustion in a recuperative furnace.Details of the furnace flow velocity,temperature,O2,CO2 and NOx concentrations are provided.Results obtained suggest that the flue gas recirculation plays a vital role in establishing the premixed MILD combustion.It is also revealed that there is a critical momentum rate of the fuel-air mixture below which MILD combustion does not occur.Moreover,the momentum rate appears to have less significant influence on conventional global combustion than on MILD combustion.
基金Supported by the National Natural Science Foundation of China(20976090)the Foundation for the Author of National Excellent Doctoral Dissertation of China(200757)
文摘The partial oxidation of hydrocarbons is an important technical route to produce acetylene for chemical industry.The partial oxidation reactor is the key to high acetylene yields.This work is an experimental and numerical study on the use of a methane flame to produce acetylene.A lab scale partial oxidation reactor was used to produce ultra fuel-rich premixed jet flames.The axial temperature and species concentration profiles were measured for different equivalence ratios and preheating temperatures,and these were compared to numerical results from Computational Fluid Dynamics(CFD)simulations that used the Reynolds Averaged Navier-Stokes Probability Density Function(RANS-PDF)approach coupled with detailed chemical mechanisms.The Leeds 1.5,GRI 3.0 and San Diego mechanisms were used to investigate the effect of the detailed chemical mechanisms.The effects of equivalence ratio and preheating temperature on acetylene production were experimentally and numerically studied.The experimental validations indicated that the present numerical simulation provided reliable prediction on the partial oxidation of methane.Using this simulation method the optimal equivalence ratio for acetylene production was determined to be 3.6.Increasing preheating temperature improved acetylene production and shortened greatly the ignition delay time.So the increase of preheating temperature had to be limited to avoid uncontrolled ignition in the mixing chamber and the pyrolysis of methane in the preheater.
文摘Effect of different fire strengths on the smoke distribution in the subway station is investigated. Shin-Gum-Ho station （line #5） in Seoui is selected as a case study for variation of CO （carbon monoxide） distribution caused by the fire in the platform. The ventilation in the station is set to be an air supply mod in the lobby and an air exhaustion mod in the platform. One-side main tunnel ventilation （7,000 m3/min） is applied to operate in the tunnel. The fire is assumed to break out in the middle of train parked in the platform tunnel. Two kinds of fire strength are used. One is 10 MW and the other is 20 MW. Ventilation diffusers in the station are modeled as 317 square shapes ＆ four rectangular shapes in the lobby and platform. The total of 7.5 million grids is generated and whole domain is divided to 22 blocks for parallel computation. Large eddy simulation method is applied to solve the momentum equation. The behavior of CO is calculated according to different fire strengths and compared with each other.
