Liquid-metal cooling(LMC)process can offer refinement of microstructure and reduce defects due to the increased cooling rate from enhanced heat extraction,and thus an understanding of solidification behavior in nickel...Liquid-metal cooling(LMC)process can offer refinement of microstructure and reduce defects due to the increased cooling rate from enhanced heat extraction,and thus an understanding of solidification behavior in nickel-based superalloy casting during LMC process is essential for improving mechanical performance of single crystal(SC)castings.In this effort,an integrated heat transfer model coupling meso grain structure and micro dendrite is developed to predict the temperature distribution and microstructure evolution in LMC process.An interpolation algorithm is used to deal with the macro-micro grids coupling issues.The algorithm of cells capture is also modified,and a deterministic cellular automaton(DCA)model is proposed to describe neighborhood cell tracking.In addition,solute distribution is also considered to describe the dendrite growth.Temperature measuring,EBSD,OM and SEM experiments are implemented to verify the proposed model,and the experiment results agree well with the simulation results.Several simulations are performed with a range of withdrawal rates,and the results indicate that 12 mm·min^(-1)is suitable for LMC process in this work,which can result in a fairly narrow and flat mushy zone and correspondingly exhibited fairly straight grains.The mushy zone length is about 4.8 mm in the steady state and the average deviation angle of grains is about 13.9°at the height 90 mm from the casting base under 12 mm·min^(-1)withdrawal process.The competitive phenomenon of dendrites at different withdrawal rates is also observed,which has a great relevant to the temperature fluctuation.展开更多
Fengyun-3F(FY-3F)represents the cutting edge in polar-orbiting meteorological satellite technology,developed by China.It possesses enhanced comprehensive observational capabilities,facilitating continuous optical and ...Fengyun-3F(FY-3F)represents the cutting edge in polar-orbiting meteorological satellite technology,developed by China.It possesses enhanced comprehensive observational capabilities,facilitating continuous optical and microwave imaging,as well as detailed vertical profiling of the Earth’s atmosphere.One of the key features of FY-3F satellite lies in its deployment of an advanced broadband sensor,Earth Radiation Measurement-II(ERM-II).However,there is still a lack of an effective algorithm to derive shortwave radiation components based on the improved measurements of ERM-II.This study attempts to utilize ERM-II data to simultaneously derive top of atmosphere(TOA)and surface shortwave radiation components,including TOA albedo,surface shortwave downward radiation(SWDR),and photosynthetically active radiation(PAR),based on a look-up table(LUT)scheme.In the absence of direct measurements,the estimated TOA albedo was compared with the Clouds and the Earth’s Radiant Energy System(CERES)Single Scanner Footprint(SSF)products,yielding a high correlation,with a correlation coefficient(R^(2))of 0.87,bias of 0.0090,and root mean square error(RMSE)of 0.0418.SWDR and PAR were validated against in situ measurements from 21 sites within Baseline Surface Radiation Network(BSRN)and Surface Radiation Budget Network(SURFRAD),with R^(2) of 0.89 and 0.83,biases of−10.5 and−8.0 W/m^(2),and RMSEs of 104.8 and 48.1 W/m^(2),respectively.To examine the theoretical accuracies of the proposed scheme,a simulated dataset was additionally constructed for comprehensive validation.The verification indicates that the estimated TOA albedo,SWDR,and PAR show strong agreement with radiative transfer simulations,with R^(2) of 0.98,0.96,and 0.96,respectively.The corresponding RMSEs are 0.028,48.1 W/m^(2),and 22.4 W/m^(2),while the biases are−0.0004,−1.0 W/m^(2),and 0.4 W/m^(2).The proposed algorithm provides novel ideas that enable the simultaneous estimation of multiple shortwave variables under all-sky conditions based on broadband sensors.展开更多
基金supported by the National Natural Science Foundation of China(No.51904276)Science and Technology Development Program of Henan Province(No.192102210013,202102210080)National Science and Technology Major Project(No.2017-VII-0008-0101)。
文摘Liquid-metal cooling(LMC)process can offer refinement of microstructure and reduce defects due to the increased cooling rate from enhanced heat extraction,and thus an understanding of solidification behavior in nickel-based superalloy casting during LMC process is essential for improving mechanical performance of single crystal(SC)castings.In this effort,an integrated heat transfer model coupling meso grain structure and micro dendrite is developed to predict the temperature distribution and microstructure evolution in LMC process.An interpolation algorithm is used to deal with the macro-micro grids coupling issues.The algorithm of cells capture is also modified,and a deterministic cellular automaton(DCA)model is proposed to describe neighborhood cell tracking.In addition,solute distribution is also considered to describe the dendrite growth.Temperature measuring,EBSD,OM and SEM experiments are implemented to verify the proposed model,and the experiment results agree well with the simulation results.Several simulations are performed with a range of withdrawal rates,and the results indicate that 12 mm·min^(-1)is suitable for LMC process in this work,which can result in a fairly narrow and flat mushy zone and correspondingly exhibited fairly straight grains.The mushy zone length is about 4.8 mm in the steady state and the average deviation angle of grains is about 13.9°at the height 90 mm from the casting base under 12 mm·min^(-1)withdrawal process.The competitive phenomenon of dendrites at different withdrawal rates is also observed,which has a great relevant to the temperature fluctuation.
基金supported by the National Natural Science Foundation of China(NSFC)under project 42371342the Innovation Group Project of Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai)under grant 311022003.
文摘Fengyun-3F(FY-3F)represents the cutting edge in polar-orbiting meteorological satellite technology,developed by China.It possesses enhanced comprehensive observational capabilities,facilitating continuous optical and microwave imaging,as well as detailed vertical profiling of the Earth’s atmosphere.One of the key features of FY-3F satellite lies in its deployment of an advanced broadband sensor,Earth Radiation Measurement-II(ERM-II).However,there is still a lack of an effective algorithm to derive shortwave radiation components based on the improved measurements of ERM-II.This study attempts to utilize ERM-II data to simultaneously derive top of atmosphere(TOA)and surface shortwave radiation components,including TOA albedo,surface shortwave downward radiation(SWDR),and photosynthetically active radiation(PAR),based on a look-up table(LUT)scheme.In the absence of direct measurements,the estimated TOA albedo was compared with the Clouds and the Earth’s Radiant Energy System(CERES)Single Scanner Footprint(SSF)products,yielding a high correlation,with a correlation coefficient(R^(2))of 0.87,bias of 0.0090,and root mean square error(RMSE)of 0.0418.SWDR and PAR were validated against in situ measurements from 21 sites within Baseline Surface Radiation Network(BSRN)and Surface Radiation Budget Network(SURFRAD),with R^(2) of 0.89 and 0.83,biases of−10.5 and−8.0 W/m^(2),and RMSEs of 104.8 and 48.1 W/m^(2),respectively.To examine the theoretical accuracies of the proposed scheme,a simulated dataset was additionally constructed for comprehensive validation.The verification indicates that the estimated TOA albedo,SWDR,and PAR show strong agreement with radiative transfer simulations,with R^(2) of 0.98,0.96,and 0.96,respectively.The corresponding RMSEs are 0.028,48.1 W/m^(2),and 22.4 W/m^(2),while the biases are−0.0004,−1.0 W/m^(2),and 0.4 W/m^(2).The proposed algorithm provides novel ideas that enable the simultaneous estimation of multiple shortwave variables under all-sky conditions based on broadband sensors.
