Upon investigating the relative locations of internal and external forcing and the resultant mean meridional circula- tion,it was found that thermal forcing and mechanical forcing for the formation of atmospheric mean...Upon investigating the relative locations of internal and external forcing and the resultant mean meridional circula- tion,it was found that thermal forcing and mechanical forcing for the formation of atmospheric mean meridional circu- lation are modulated by a certain ratio.This ratio is determined by the inherent baroclinity,static stability and absolute vorticity of the atmosphere. By employing a parameterization scheme for radiative heating and condensation heating,together with the analysis data of the European Center for Medium-range Weather Forecasts,the mean meridional circulation for January was simulated numerically.It was found that latent heat release in the tropics may result in the formation of double-layered Hadley circulation,so do the eddy momentum transfer processes.On the other hand,mean meridional circulations in ex- tra-tropics are mainly determined by external momentum forcing and atmospheric properties of eddy momentum and heat transfer.展开更多
Refurbishment of thermal barrier coating(TBC)has become a valuable technique to prolong the service life of high-temperature components.This study investigates the effect of the refurbishment process(coating removal a...Refurbishment of thermal barrier coating(TBC)has become a valuable technique to prolong the service life of high-temperature components.This study investigates the effect of the refurbishment process(coating removal and recoating)on the microstructure evolution and physical properties of TBC,including oxidation characteristics,element diffusion behavior,and crack failure mechanisms.The results showed that a certain amount of interdiffusion zone(IDZ)with Cr-rich would be retained in DD6 superalloy substrate after coating removal.The microstructure of the refurbished specimens showed equiaxedβ-NiAl phases,while the ordinary specimens have elongated grain shapes with a high aspect ratio.Moreover,mixed oxides in the refurbished TBC specimens were earlier observed during cyclic oxidation,with a greater thickness compared to ordinary TBC,due to the influence of BC layer phase sizes.The growth mechanism of thermally grown oxide(TGO-Al_(2)O_(3)layer)in the refurbished TBC specimens was also different,resulting from the different mechanisms of mixed oxides growth.Furthermore,under cyclic oxidation with water quenching at 1100℃,the cracks in the refurbished specimen tend to occur in the mixed oxides layer,while the cracks in the ordinary specimen occur in the top coat(TC)layer,attributing to the earlier and thicker mixed oxides layer formed in refurbished specimens.展开更多
文摘Upon investigating the relative locations of internal and external forcing and the resultant mean meridional circula- tion,it was found that thermal forcing and mechanical forcing for the formation of atmospheric mean meridional circu- lation are modulated by a certain ratio.This ratio is determined by the inherent baroclinity,static stability and absolute vorticity of the atmosphere. By employing a parameterization scheme for radiative heating and condensation heating,together with the analysis data of the European Center for Medium-range Weather Forecasts,the mean meridional circulation for January was simulated numerically.It was found that latent heat release in the tropics may result in the formation of double-layered Hadley circulation,so do the eddy momentum transfer processes.On the other hand,mean meridional circulations in ex- tra-tropics are mainly determined by external momentum forcing and atmospheric properties of eddy momentum and heat transfer.
基金supported by the National Science and Technology Major Project(J2019-IV-0003-0070)National Natural Science Foundation of China(12102320)China Postdoctoral Science Foundation(2021M692571).
文摘Refurbishment of thermal barrier coating(TBC)has become a valuable technique to prolong the service life of high-temperature components.This study investigates the effect of the refurbishment process(coating removal and recoating)on the microstructure evolution and physical properties of TBC,including oxidation characteristics,element diffusion behavior,and crack failure mechanisms.The results showed that a certain amount of interdiffusion zone(IDZ)with Cr-rich would be retained in DD6 superalloy substrate after coating removal.The microstructure of the refurbished specimens showed equiaxedβ-NiAl phases,while the ordinary specimens have elongated grain shapes with a high aspect ratio.Moreover,mixed oxides in the refurbished TBC specimens were earlier observed during cyclic oxidation,with a greater thickness compared to ordinary TBC,due to the influence of BC layer phase sizes.The growth mechanism of thermally grown oxide(TGO-Al_(2)O_(3)layer)in the refurbished TBC specimens was also different,resulting from the different mechanisms of mixed oxides growth.Furthermore,under cyclic oxidation with water quenching at 1100℃,the cracks in the refurbished specimen tend to occur in the mixed oxides layer,while the cracks in the ordinary specimen occur in the top coat(TC)layer,attributing to the earlier and thicker mixed oxides layer formed in refurbished specimens.
